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Showing 1 - 200 of 3031 Journals sorted alphabetically
AASRI Procedia     Open Access   (Followers: 15)
Academic Pediatrics     Hybrid Journal   (Followers: 20, SJR: 1.402, h-index: 51)
Academic Radiology     Hybrid Journal   (Followers: 16, SJR: 1.008, h-index: 75)
Accident Analysis & Prevention     Partially Free   (Followers: 79, SJR: 1.109, h-index: 94)
Accounting Forum     Hybrid Journal   (Followers: 22, SJR: 0.612, h-index: 27)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 27, SJR: 2.515, h-index: 90)
Achievements in the Life Sciences     Open Access   (Followers: 4)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 5, SJR: 0.338, h-index: 19)
Acta Astronautica     Hybrid Journal   (Followers: 303, SJR: 0.726, h-index: 43)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 3)
Acta Biomaterialia     Hybrid Journal   (Followers: 25, SJR: 2.02, h-index: 104)
Acta Colombiana de Cuidado Intensivo     Full-text available via subscription  
Acta de Investigación Psicológica     Open Access   (Followers: 2)
Acta Ecologica Sinica     Open Access   (Followers: 8, SJR: 0.172, h-index: 29)
Acta Haematologica Polonica     Free   (SJR: 0.123, h-index: 8)
Acta Histochemica     Hybrid Journal   (Followers: 3, SJR: 0.604, h-index: 38)
Acta Materialia     Hybrid Journal   (Followers: 196, SJR: 3.683, h-index: 202)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5, SJR: 0.615, h-index: 21)
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9, SJR: 0.442, h-index: 21)
Acta Oecologica     Hybrid Journal   (Followers: 9, SJR: 0.915, h-index: 53)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription   (Followers: 1)
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 3, SJR: 0.311, h-index: 16)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 2)
Acta Poética     Open Access   (Followers: 4)
Acta Psychologica     Hybrid Journal   (Followers: 21, SJR: 1.365, h-index: 73)
Acta Sociológica     Open Access  
Acta Tropica     Hybrid Journal   (Followers: 5, SJR: 1.059, h-index: 77)
Acta Urológica Portuguesa     Open Access  
Actas Dermo-Sifiliograficas     Full-text available via subscription   (Followers: 4)
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Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 4, SJR: 0.112, h-index: 2)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 4)
Ad Hoc Networks     Hybrid Journal   (Followers: 11, SJR: 0.967, h-index: 57)
Addictive Behaviors     Hybrid Journal   (Followers: 15, SJR: 1.514, h-index: 92)
Addictive Behaviors Reports     Open Access   (Followers: 5)
Additive Manufacturing     Hybrid Journal   (Followers: 7, SJR: 1.039, h-index: 5)
Additives for Polymers     Full-text available via subscription   (Followers: 20)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 119, SJR: 5.2, h-index: 222)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 11, SJR: 1.265, h-index: 53)
Advanced Powder Technology     Hybrid Journal   (Followers: 16, SJR: 0.739, h-index: 33)
Advances in Accounting     Hybrid Journal   (Followers: 8, SJR: 0.299, h-index: 15)
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Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 3)
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Advances In Atomic, Molecular, and Optical Physics     Full-text available via subscription   (Followers: 16, SJR: 3.31, h-index: 42)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4, SJR: 2.277, h-index: 43)
Advances in Botanical Research     Full-text available via subscription   (Followers: 3, SJR: 0.619, h-index: 48)
Advances in Cancer Research     Full-text available via subscription   (Followers: 26, SJR: 2.215, h-index: 78)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9, SJR: 0.9, h-index: 30)
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Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 12)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 24, SJR: 0.183, h-index: 23)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 10, SJR: 0.665, h-index: 29)
Advances in Chronic Kidney Disease     Full-text available via subscription   (Followers: 8, SJR: 1.268, h-index: 45)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 28, SJR: 0.938, h-index: 33)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 18, SJR: 2.314, h-index: 130)
Advances in Computers     Full-text available via subscription   (Followers: 16, SJR: 0.223, h-index: 22)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 11)
Advances in Digestive Medicine     Open Access   (Followers: 4)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 5)
Advances in Drug Research     Full-text available via subscription   (Followers: 22)
Advances in Ecological Research     Full-text available via subscription   (Followers: 39, SJR: 3.25, h-index: 43)
Advances in Engineering Software     Hybrid Journal   (Followers: 25, SJR: 0.486, h-index: 10)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 7)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 38, SJR: 5.465, h-index: 64)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 3)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 41, SJR: 0.674, h-index: 38)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 14)
Advances in Genetics     Full-text available via subscription   (Followers: 15, SJR: 2.558, h-index: 54)
Advances in Genome Biology     Full-text available via subscription   (Followers: 11)
Advances in Geophysics     Full-text available via subscription   (Followers: 6, SJR: 2.325, h-index: 20)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 18, SJR: 0.906, h-index: 24)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8, SJR: 0.497, h-index: 31)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 22)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 2, SJR: 0.396, h-index: 27)
Advances in Immunology     Full-text available via subscription   (Followers: 33, SJR: 4.152, h-index: 85)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 9, SJR: 1.132, h-index: 42)
Advances in Insect Physiology     Full-text available via subscription   (Followers: 3, SJR: 1.274, h-index: 27)
Advances in Integrative Medicine     Hybrid Journal   (Followers: 4)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 4)
Advances in Life Course Research     Hybrid Journal   (Followers: 7, SJR: 0.764, h-index: 15)
Advances in Lipobiology     Full-text available via subscription   (Followers: 1)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Marine Biology     Full-text available via subscription   (Followers: 16, SJR: 1.645, h-index: 45)
Advances in Mathematics     Full-text available via subscription   (Followers: 10, SJR: 3.261, h-index: 65)
Advances in Medical Sciences     Hybrid Journal   (Followers: 5, SJR: 0.489, h-index: 25)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 4, SJR: 1.44, h-index: 51)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 21)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 10)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 6, SJR: 0.324, h-index: 8)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 3)
Advances in Oncobiology     Full-text available via subscription   (Followers: 3)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15, SJR: 2.885, h-index: 45)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7, SJR: 0.148, h-index: 11)
Advances in Parasitology     Full-text available via subscription   (Followers: 7, SJR: 2.37, h-index: 73)
Advances in Pediatrics     Full-text available via subscription   (Followers: 20, SJR: 0.4, h-index: 28)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 14)
Advances in Pharmacology     Full-text available via subscription   (Followers: 13, SJR: 1.718, h-index: 58)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 7, SJR: 0.384, h-index: 26)
Advances in Phytomedicine     Full-text available via subscription  
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3, SJR: 0.248, h-index: 11)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 8)
Advances in Plant Pathology     Full-text available via subscription   (Followers: 5)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 17, SJR: 1.5, h-index: 62)
Advances in Psychology     Full-text available via subscription   (Followers: 56)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5, SJR: 0.478, h-index: 32)
Advances in Radiation Oncology     Open Access  
Advances in Small Animal Medicine and Surgery     Hybrid Journal   (Followers: 1, SJR: 0.1, h-index: 2)
Advances in Space Research     Full-text available via subscription   (Followers: 332, SJR: 0.606, h-index: 65)
Advances in Structural Biology     Full-text available via subscription   (Followers: 7)
Advances in Surgery     Full-text available via subscription   (Followers: 6, SJR: 0.823, h-index: 27)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 28, SJR: 1.321, h-index: 56)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 14)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 12)
Advances in Virus Research     Full-text available via subscription   (Followers: 5, SJR: 1.878, h-index: 68)
Advances in Water Resources     Hybrid Journal   (Followers: 42, SJR: 2.408, h-index: 94)
Aeolian Research     Hybrid Journal   (Followers: 5, SJR: 0.973, h-index: 22)
Aerospace Science and Technology     Hybrid Journal   (Followers: 303, SJR: 0.816, h-index: 49)
AEU - Intl. J. of Electronics and Communications     Hybrid Journal   (Followers: 8, SJR: 0.318, h-index: 36)
African J. of Emergency Medicine     Open Access   (Followers: 4, SJR: 0.344, h-index: 6)
Ageing Research Reviews     Hybrid Journal   (Followers: 7, SJR: 3.289, h-index: 78)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 388, SJR: 1.385, h-index: 72)
Agri Gene     Hybrid Journal  
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 15, SJR: 2.18, h-index: 116)
Agricultural Systems     Hybrid Journal   (Followers: 29, SJR: 1.275, h-index: 74)
Agricultural Water Management     Hybrid Journal   (Followers: 36, SJR: 1.546, h-index: 79)
Agriculture and Agricultural Science Procedia     Open Access  
Agriculture and Natural Resources     Open Access   (Followers: 1)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 48, SJR: 1.879, h-index: 120)
Ain Shams Engineering J.     Open Access   (Followers: 5, SJR: 0.434, h-index: 14)
Air Medical J.     Hybrid Journal   (Followers: 3, SJR: 0.234, h-index: 18)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.285, h-index: 3)
Alcohol     Hybrid Journal   (Followers: 9, SJR: 0.922, h-index: 66)
Alcoholism and Drug Addiction     Open Access   (Followers: 5)
Alergologia Polska : Polish J. of Allergology     Full-text available via subscription   (Followers: 1)
Alexandria Engineering J.     Open Access   (Followers: 1, SJR: 0.436, h-index: 12)
Alexandria J. of Medicine     Open Access  
Algal Research     Partially Free   (Followers: 7, SJR: 2.05, h-index: 20)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
Allergologia et Immunopathologia     Full-text available via subscription   (Followers: 1, SJR: 0.46, h-index: 29)
Allergology Intl.     Open Access   (Followers: 5, SJR: 0.776, h-index: 35)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 6, SJR: 0.158, h-index: 9)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 45, SJR: 4.289, h-index: 64)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 5)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 3)
American Heart J.     Hybrid Journal   (Followers: 45, SJR: 3.157, h-index: 153)
American J. of Cardiology     Hybrid Journal   (Followers: 47, SJR: 2.063, h-index: 186)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 34, SJR: 0.574, h-index: 65)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 6, SJR: 1.091, h-index: 45)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 14, SJR: 1.653, h-index: 93)
American J. of Human Genetics     Hybrid Journal   (Followers: 32, SJR: 8.769, h-index: 256)
American J. of Infection Control     Hybrid Journal   (Followers: 25, SJR: 1.259, h-index: 81)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 31, SJR: 2.313, h-index: 172)
American J. of Medicine     Hybrid Journal   (Followers: 48, SJR: 2.023, h-index: 189)
American J. of Medicine Supplements     Full-text available via subscription   (Followers: 3)
American J. of Obstetrics and Gynecology     Hybrid Journal   (Followers: 173, SJR: 2.255, h-index: 171)
American J. of Ophthalmology     Hybrid Journal   (Followers: 51, SJR: 2.803, h-index: 148)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 2)
American J. of Orthodontics and Dentofacial Orthopedics     Full-text available via subscription   (Followers: 6, SJR: 1.249, h-index: 88)
American J. of Otolaryngology     Hybrid Journal   (Followers: 22, SJR: 0.59, h-index: 45)
American J. of Pathology     Hybrid Journal   (Followers: 23, SJR: 2.653, h-index: 228)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 21, SJR: 2.764, h-index: 154)
American J. of Surgery     Hybrid Journal   (Followers: 32, SJR: 1.286, h-index: 125)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 13, SJR: 0.653, h-index: 70)
Ampersand : An Intl. J. of General and Applied Linguistics     Open Access   (Followers: 5)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.066, h-index: 51)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 52, SJR: 0.124, h-index: 9)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 3)
Anales de Cirugia Vascular     Full-text available via subscription  
Anales de Pediatría     Full-text available via subscription   (Followers: 2, SJR: 0.209, h-index: 27)
Anales de Pediatría (English Edition)     Full-text available via subscription  
Anales de Pediatría Continuada     Full-text available via subscription   (SJR: 0.104, h-index: 3)
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 2, SJR: 2.577, h-index: 7)
Analytica Chimica Acta     Hybrid Journal   (Followers: 38, SJR: 1.548, h-index: 152)
Analytical Biochemistry     Hybrid Journal   (Followers: 151, SJR: 0.725, h-index: 154)
Analytical Chemistry Research     Open Access   (Followers: 7, SJR: 0.18, h-index: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 10)
Anesthésie & Réanimation     Full-text available via subscription  
Anesthesiology Clinics     Full-text available via subscription   (Followers: 21, SJR: 0.421, h-index: 40)
Angiología     Full-text available via subscription   (SJR: 0.124, h-index: 9)
Angiologia e Cirurgia Vascular     Open Access  
Animal Behaviour     Hybrid Journal   (Followers: 141, SJR: 1.907, h-index: 126)
Animal Feed Science and Technology     Hybrid Journal   (Followers: 5, SJR: 1.151, h-index: 83)
Animal Reproduction Science     Hybrid Journal   (Followers: 5, SJR: 0.711, h-index: 78)
Annales d'Endocrinologie     Full-text available via subscription   (SJR: 0.394, h-index: 30)
Annales d'Urologie     Full-text available via subscription  
Annales de Cardiologie et d'Angéiologie     Full-text available via subscription   (SJR: 0.177, h-index: 13)
Annales de Chirurgie de la Main et du Membre Supérieur     Full-text available via subscription  
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Annales de Chirurgie Vasculaire     Full-text available via subscription   (Followers: 1)

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Journal Cover Agricultural Water Management
  [SJR: 1.546]   [H-I: 79]   [36 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0378-3774
   Published by Elsevier Homepage  [3031 journals]
  • Responses of field evapotranspiration to the changes of cropping pattern
           and groundwater depth in large irrigation district of Yellow River basin
    • Authors: Liangliang Bai; Jiabing Cai; Yu Liu; He Chen; Baozhong Zhang; Lingxu Huang
      Pages: 1 - 11
      Abstract: Publication date: 1 July 2017
      Source:Agricultural Water Management, Volume 188
      Author(s): Liangliang Bai, Jiabing Cai, Yu Liu, He Chen, Baozhong Zhang, Lingxu Huang
      To solve the problems of decreasing water resources from the Yellow River, the renovation project of water-saving and controlling water distribution was implemented in the Hetao Irrigation District of North China since 1999. The local hydrological cycle is expected to be influenced or changed during the past fifteen years through the project. Jiefangzha Irrigation Region, the second large partition of the Hetao Irrigation District, was selected as the typical area to explore the relationship between agricultural water consumption, water distribution, cropping pattern and changing groundwater level. In this paper, the SEBS (Surface Energy Balance System) model and the ESTARFM (Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model) algorithm were applied to produce daily field-scale evapotranspiration (ET) based on Landsat and MODIS data from 2000 to 2015 at intervals. The results indicate that the cropping pattern had changed greatly, while the water table descended through the years. The total agriculture ET stayed relatively stable, with the average annual consumption of 8.9×108 m3. The temporal variation of agriculture ET was not obviously sensitive to the adjustment of cropping pattern. There was no significant difference in April–October ET for different crops, in spite of the clear distinction of ET in each crop-specific growing season. The spatial distribution of agricultural ET did not change in spite of the great adjustment of cropping pattern during fifteen years, which has a close inverse correlation with the groundwater depth. Groundwater depth descended from 1.76m to 2.33m during the operation period of the water-saving project, which might reduce the soil evaporation and have a positive effect on soil salinization effectively. Meanwhile, the net irrigation water use efficiency was improved from 0.59 to 0.66. These effects indicate the positive impact of the implemented water-saving renovation project on water management and environment. However, the actual crop coefficient K c,a decreased slightly with the gradually increasing reference evapotranspiration, indicating possible drought stress as an effect of the continuing reduction of the availability of net irrigation water and declining groundwater table.

      PubDate: 2017-04-09T13:45:44Z
      DOI: 10.1016/j.agwat.2017.03.028
      Issue No: Vol. 188 (2017)
  • Changing soil hydraulic properties and water repellency in a pomegranate
           orchard irrigated with saline water by applying polyacrylamide
    • Authors: M. Tadayonnejad; M.R. Mosaddeghi; Sh. Ghorbani Dashtaki
      Pages: 12 - 20
      Abstract: Publication date: 1 July 2017
      Source:Agricultural Water Management, Volume 188
      Author(s): M. Tadayonnejad, M.R. Mosaddeghi, Sh. Ghorbani Dashtaki
      Soil wettability and water repellency are important physical properties which greatly affect soil-water relations. This study was conducted to investigate the effects of polyacrylamide (PAM) on soil water repellency and wettability in a pomegranate orchard drip irrigated with saline water in Isfahan Province, central Iran. The experiment was a randomized complete block design conducted within each “durations of drip irrigation” (considered as the environment) including control (uncultivated), and 8 and 15 years old trees under drip irrigation system (DIS). PAM concentrations were 0 (control), 10 and 20mgl−1 arranged in each block at three replications. The PAM (solubilized in saline water with electrical conductivity of 6.2dSm−1) with the mentioned concentrations was applied once during the irrigation time. A week after applying the PAM, soil samples were taken from 0 to 0.3, 0.3–0.6 and 0.6–0.9m depths under the emitters. Water repellency index (WRI) and soil-water contact angle (β) were determined using intrinsic sorptivity method by measuring the water and ethanol sorptivities in all soil samples. Increasing the duration of irrigation with saline water increased electrical conductivity (ECe), concentrations of (Ca2+ +Mg2+) and Na +, and sodium adsorption ratio (SAR) of the saturated extract in the 0–0.3m soil layer under the emitters. Increasing the duration of irrigation also increased WRI and β, and decreased water infiltration, especially in the 0–0.3m soil layer, presumably through enhancing effects of long-term use of saline water on surface tension of water, soil aggregate stability, physical protection of organic matter in soil and stability of hydrophobic coatings. PAM application significantly reduced soil water repellency and increased soil water sorptivity. In the 0–0.3m, 8 and 15 years of drip irrigation increased the WRI by 56 and 134 percent, respectively, compared with the control. PAM application at rates of 10 and 20mgl−1 decreased WRI by 27 and 40 percent, respectively, when compared with the control. Application of 20mgl−1 of PAM could completely ameliorate the degradative effects of drip irrigation with saline water for 8 years, whereas amelioration in the 15-year treatment remained incomplete.

      PubDate: 2017-04-09T13:45:44Z
      DOI: 10.1016/j.agwat.2017.03.026
      Issue No: Vol. 188 (2017)
  • Rice sensitivity to saline irrigation in Southern Spain
    • Authors: Manuel Aguilar; José Luis Fernández-Ramírez; María Aguilar-Blanes; Clemente Ortiz-Romero
      Pages: 21 - 28
      Abstract: Publication date: 1 July 2017
      Source:Agricultural Water Management, Volume 188
      Author(s): Manuel Aguilar, José Luis Fernández-Ramírez, María Aguilar-Blanes, Clemente Ortiz-Romero
      Losses of productivity of flooded rice in Southern Spain may occur due to the use of saline water coming from the existent tidal regime in the marshes of Guadalquivir River, and the sensibility of the plants is variable according to its stage of development. The aim of this research was to evaluate the production of rice grains and its components, spikelet sterility and the phenological development of rice at different levels of salinity and in different periods of its cycle. In the conditions of the trial, the productive potential of rice based on the electrical conductivity (EC) of the irrigation water can be estimated by using the equation “Percentage of grain yield =100−12.0 (EC – 0.92)”. It was estimated that from 1.6–1.7dSm−1 salt content affects rice grain yield. Salinity also had a negative impact on a number of yield components including panicles per surface unit, tillers and spikelets per plant; floret sterility; and even delayed heading. Individual grain size was scarcely affected by salinity increase. The vegetative and reproductive phases were significantly more sensitive to salinity than grain filling and maturation phase. Irrigation management practices should be adopted to minimize salinity during these critical growth stages.

      PubDate: 2017-04-16T03:15:41Z
      DOI: 10.1016/j.agwat.2017.03.027
      Issue No: Vol. 188 (2017)
  • Association of photosynthetic traits with water use efficiency and SPAD
    • Authors: Darunee Puangbut; Sanun Jogloy; Nimitr Vorasoot
      Pages: 29 - 35
      Abstract: Publication date: 1 July 2017
      Source:Agricultural Water Management, Volume 188
      Author(s): Darunee Puangbut, Sanun Jogloy, Nimitr Vorasoot
      The impact of water stress on plant growth, tuber yield and inulin content has been widely studied but there is limited information on the effect of drought on photosynthetic characteristics. Therefore, this study was to investigate the effect of water stress on photosynthetic characteristics in Jerusalem artichoke genotypes with different levels of drought tolerance. Two experiments were conducted in rhizobox under greenhouse conditions during August to October in 2015 and 2016. A factorial experiment in randomized complete block design with three replications was used. Factor A were two water regimes (irrigated=field capacity; (FC) and water stress) and factor B were three Jerusalem artichoke genotypes. Data were recorded for relative water content, SPAD chlorophyll meter reading (SCMR), photosynthetic characteristics and water use efficiency (WUE) at 7 and 30days after imposing drought. Leaf area and dry matter was recorded at 30days after imposing drought. Our results revealed that drought caused a greater reduction in stomatal conductance (g s), net photosynthetic rate (Pn), leaf area and biomass production than in other traits measured. In contrast, WUE and SCMR were increased under drought conditions. However, g s and Pn decreases were less in resistant Jerusalem artichoke genotypes than in susceptible genotypes. Also, resistant genotypes had higher WUE increases than susceptible genotypes. Improved Pn combined with high WUE could contribute to higher biomass production. Interestingly, SCMR was associated with Pn and this trait could be used as surrogate trait for improved Pn under drought conditions.

      PubDate: 2017-04-16T03:15:41Z
      DOI: 10.1016/j.agwat.2017.04.001
      Issue No: Vol. 188 (2017)
  • Assessing plant water status in a hedgerow olive orchard from thermography
           at plant level
    • Authors: I.F. García-Tejero; A. Hernández; C.M. Padilla-Díaz; A. Diaz-Espejo; J.E Fernández
      Pages: 50 - 60
      Abstract: Publication date: 1 July 2017
      Source:Agricultural Water Management, Volume 188
      Author(s): I.F. García-Tejero, A. Hernández, C.M. Padilla-Díaz, A. Diaz-Espejo, J.E Fernández
      Water scarcity is the most limiting factor in many irrigated areas of Mediterranean countries such as South Spain. Olive growing has been traditionally associated to rain-fed agriculture, although irrigation and practices related to intensive agriculture have been progressively introduced, requiring a more precise irrigation scheduling to save water. Thermal imaging is among the alternatives to assess the crop water status, especially when deficit irrigation (DI) strategies are applied. However, this technique requires of new advances to be more user friendly and robust for practical usage. The aims of this study were: i) to define threshold values of canopy temperature (T C), Crop Water Stress Index (CWSI) and the temperature difference between canopy and the surrounding air (ΔT canopy-air) for the assessment of the olive water status when a DI strategy is applied; ii) to define the best time of the day and the best area of the canopy to carry out thermal measurements, and iii) to obtain relationships between thermal indicators and main physiological parameters useful to estimate the crop water status from thermal data. The trial was conducted during 2015, in a hedgerow olive orchard (SW Spain) with 8-year-old trees (Olea europaea L., cv. Arbequina), under three irrigation regimes: a full-irrigation treatment (FI) and two regulated deficit irrigation treatments aimed to supplying 45% of the irrigation needs. In one of them, irrigation was scheduled from leaf turgor pressure related measurements (45RDITP). In the other, the crop coefficient approach was used to schedule irrigation (45RDICC). Significant correlations between Tc versus stem water potential (Ψ st) and leaf gas-exchange parameters (stomatal conductance to water vapour, g s; net CO2 assimilation, A N; transpiration, E) were obtained (p≤0.05), in particular from measurements taken at 10:30 GMT in the lower part of the sunlit side of the canopy. Moreover, the relationships between both ΔT canopy-air and CWSI with the monitored physiological variables were very robust. We concluded that values of ΔT canopy-air higher than 0°C and values of CWSI up to 0.2 reliably reflect the plant water stress. Our results, therefore, suggest that both ΔT canopy-air and CWSI measured at midday provide reliable information on the tree water status and are useful to schedule irrigation in hedgerow olive orchards, especially under DI conditions.
      Graphical abstract image

      PubDate: 2017-04-23T03:30:59Z
      DOI: 10.1016/j.agwat.2017.04.004
      Issue No: Vol. 188 (2017)
  • A simple and alternative approach based on reference evapotranspiration
           and leaf area index for estimating tree transpiration in semi-arid regions
    • Authors: A. Ayyoub; S. Er-Raki; S. Khabba; O. Merlin; J. Ezzahar; J.C. Rodriguez; A. Bahlaoui; A. Chehbouni
      Pages: 61 - 68
      Abstract: Publication date: 1 July 2017
      Source:Agricultural Water Management, Volume 188
      Author(s): A. Ayyoub, S. Er-Raki, S. Khabba, O. Merlin, J. Ezzahar, J.C. Rodriguez, A. Bahlaoui, A. Chehbouni
      The present work aims to develop a simple approach relating normalized daily sap flow (liters per unit of leaf area) and daily reference evapotranspiration (ET0) (mm/day). Two methods (FAO-Penman-Monteith (FAO-PM) and Hargreaves-Samani (HARG)) of the calculation of ET0 were tested in order to examine their impact on the established relationships. The data sets used for developing this approach are taken over well irrigated orchards from three experimental sites (olive trees, cv. “Olea europaea L.”, olive trees, cv. “Arbequino” and citrus trees cv. “Clementine Afourar”) conducted in the Tensift region around Marrakech (center of Morocco) and one experimental site (pecan orchard, cv. “Carya illinoinensis, Wangenh. K. Koch”) conducted in the Yaqui Valley, northwest of Mexico). The results showed that the normalized daily sap flow was linearly correlated with ET0 (mm per day) calculated by FAO-PM method. The coefficient of determination (R2) and the slope of this linear regression varied between 0.71 and 0.97 and between 0.30 and 0.35, respectively, depending on the type of orchards. For HARG method, the relationship between both terms is also linear but with more discrepancy (R2 =0.7). This was somehow expected since this method is known to underestimate ET0 values in the semi-arid areas. Afterward, the validation of the developed linear relationship was performed over an olive orchard (“Olea europaea L.”) where the measurements of sap flow were available for another cropping season (2004). The scatter plot between the normalized measured and estimated sap flow based on FAO-PM method reveals a very good agreement (slope=1, and RMSE=0.14L/m2 leaf area). However, for the estimation of normalized sap flow based on HARG method, the correlation is relatively more scattered (slope=0.95, and RMSE=0.35L/m2 leaf area). A further validation was performed using the measurements of evapotranspiration (ET) by eddy correlation system and the results showed that the correlation between normalized measured ET and estimated normalized sap flow is best when using FAO-PM method (RMSE=0.33L/m2 leaf area) for estimating ET0 than when using HARG method (RMSE=0.51L/m2 leaf area). Finally, the performance of the developed approach was compared to the traditional dual crop coefficient scheme for estimating plant transpiration. Cross-comparison of these two approaches with the measurements data gave satisfactory results with an average value of RMSE equal to about 0.37mm/day for both approaches.

      PubDate: 2017-04-23T03:30:59Z
      DOI: 10.1016/j.agwat.2017.04.005
      Issue No: Vol. 188 (2017)
  • Effect of irrigation with sea water on soil salinity and yield of oleic
    • Authors: Mabood Farhadi Machekposhti; Ali Shahnazari; Mirkhalegh Z. Ahmadi; Ghasem Aghajani; Henk Ritzema
      Pages: 69 - 78
      Abstract: Publication date: 1 July 2017
      Source:Agricultural Water Management, Volume 188
      Author(s): Mabood Farhadi Machekposhti, Ali Shahnazari, Mirkhalegh Z. Ahmadi, Ghasem Aghajani, Henk Ritzema
      A field trial was carried out in 2013 and 2014 in a research field near Sari (Iran), to study the effect of irrigation with Caspian Sea water on soil salinity, growth parameters and yield components of oleic sunflower. The experiment was conducted with 4 levels of blending viz. 0% (S0) (fresh water), 15% (S15), 30% (S30) and 45% (S45) mix of sea and fresh water. Soil salinity in the soil profile up to 0–1.0m increased from 1.1dSm−1 (before sowing) to 1.4, 2.1, 2.8 and 3.6dSm−1 for S0, S15, S30 and S45, respectively. In the off-season, soil salinity decreased again to its original level in the control (S0) and to 1.3, 1.8 and 2.7dSm−1 respectively in S15, S30 and S45, due to rainfall. The corresponding oil yield decreased from 2.6tha−1 (S0) to 2.4, 2.0 and 1.5tha−1 respectively for S15, S30 and S45. This corresponds to a yield reduction of 10–14% for every 1dSm−1 increase in soil salinity. The results also indicate that salinity threshold value for oleic sunflower in Sari region is about 1.6dSm−1. Compared to the control (S0), irrigation with 15% and 30% of sea water had no significant effect on seed yield and irrigation water productivity based on oil yield (IWPoil). For S45, however, seed yield and IWPoil were significantly reduced by 32 and 39% in 2013, and 26 and 34% in 2014. It is concluded that, to irrigate oleic sunflower, 30% Caspian Sea water can be applied for mixing into the irrigating water in the area which has an annual rainfall of 540mm.

      PubDate: 2017-04-23T03:30:59Z
      DOI: 10.1016/j.agwat.2017.04.002
      Issue No: Vol. 188 (2017)
  • Effect of grafting and gypsum application on cucumber (Cucumis sativus L.)
           growth under saline water irrigation
    • Authors: Qing Wang; Lizhi Men; Lihong Gao; Yongqiang Tian
      Pages: 79 - 90
      Abstract: Publication date: 1 July 2017
      Source:Agricultural Water Management, Volume 188
      Author(s): Qing Wang, Lizhi Men, Lihong Gao, Yongqiang Tian
      Saline water has been increasingly used in agricultural production due to the serious high-quality water deficits in China. However, the use of saline water often leads to negative effects on both soil quality and plant growth. In this study, we investigated the effects of grafting, gypsum (GS) application and their combination on soil properties and plant growth, cucumber yield and fruit quality under irrigation with saline water. The treatments included (i) self-root plants irrigated with nonsaline water (control, C), (ii) self-root plants irrigated with 3gL−1 saline water (SW), (iii) grafted plants irrigated with 3gL−1 saline water (SW+G), (iv) self-root plants grown in GS-treated soils irrigated with 3gL−1 saline water (SW+GS), and (v) grafted plants grown in GS-treated soils irrigated with 3gL−1 saline water (SW+G+GS). In general, SW treatment significantly increased electrical conductivity (EC), Na+, Mg2+ concentration in soil, Na+ and total Na in plant, and decreased plant K+ concentration, K+/Na+ ratio, chlorophyll b, carotenoid, biomass and fruit yield, when compared to the C treatment. Under saline water irrigation, GS application merely increased soil EC and Ca2+ concentration and decreased soil pH and Mg2+ concentration, but did not affect most plant parameters. In contrast, grafting alleviated the negative effects of saline water on plant growth, by maintaining low Na+ but high K+/Na+ ratio in shoots, and improving most shoot growth-related parameters (e.g. chlorophyll a and b, carotenoid, stomatal conductance and transpiration rate), and eventually improved the plant biomass and fruit yield. Interestingly, the combination of grafting and GS application only showed additive enhancements in free proline, starch content and osmiophilic granule number. Our results suggested that grafting had more influence than gypsum application on cucumber growth under saline water irrigation, and was an effective approach in alleviating crop salt-stress.

      PubDate: 2017-04-23T03:30:59Z
      DOI: 10.1016/j.agwat.2017.04.003
      Issue No: Vol. 188 (2017)
  • Predicting biomass and yield of sweet pepper grown with and without
    • Authors: Marija Ćosić; Ružica Stričević; Nevenka Djurović; Djordje Moravčević; Miloš Pavlović; Mladen Todorović
      Pages: 91 - 100
      Abstract: Publication date: 1 July 2017
      Source:Agricultural Water Management, Volume 188
      Author(s): Marija Ćosić, Ružica Stričević, Nevenka Djurović, Djordje Moravčević, Miloš Pavlović, Mladen Todorović
      The applicability of the FAO AquaCrop model to simulate sweet pepper growth with and without plastic film mulching under different water supply and weather conditions is assessed. Pepper yield and biomass are simulated using the results of a two-year (2012 and 2013) field experiment conducted in Stara Pazova and a three-year (2011, 2012 and 2013) field experiment in Sombor, both in Serbia. The year 2012 was much warmer and drier than the two other years. At the Stara Pazova site, black plastic mulch was used and three different irrigation treatments applied: 1) full irrigation (F), at 100% of ETc (crop evapotranspiration); 2) deficit irrigation (R), at 80% of ETc; and 3) deficit irrigation (S), at 70% of ETc. In Sombor, only full irrigation (F*) was applied and there was no mulching. Two different cultivars (cv. Elephant Ear and Mišina) were grown in Stara Pazova and Sombor, respectively. The model was calibrated using data from the F-treatment in 2012 at Stara Pazova and F*-treatment in 2011 at Sombor, given that the highest yields were recorded in these two cases. The difference between the measured and simulated values was 2.9% and 7.5% for yield and 7.6% and −14.3% for biomass, in Stara Pazova and Sombor, respectively. The calibration results showed a very good agreement between the measured and simulated values. The deviation of simulated yields from the measured values in the validation data set depended on weather and soil conditions. Namely, the match was very good in the case of well-watered pepper grown without plastic film mulching in the average year at Sombor (1.2%), and was the worst in the extremely warm year (−45.2%). Similar differences were noted in biomass. Based on statistical indicators, the coefficient of determination (R2) of pepper yield at Stara Pazova and Sombor was 0.61 and 1.00 and the Willmott index of agreement (d), 0.79 and 0.89, respectively. Thus the AquaCrop model simulates the yield of pepper grown with and without plastic film mulching quite well. Biomass simulations resulted in slightly lower values of R2 and d. The AquaCrop model can also predict the amount of water needed for pepper grown with and without black plastic mulch.

      PubDate: 2017-04-23T03:30:59Z
      DOI: 10.1016/j.agwat.2017.04.006
      Issue No: Vol. 188 (2017)
  • Evaluation of FAO56-PM, empirical, semi-empirical and gene expression
           programming approaches for estimating daily reference evapotranspiration
           in hyper-arid regions of Iran
    • Authors: Jalal Shiri
      Pages: 101 - 114
      Abstract: Publication date: 1 July 2017
      Source:Agricultural Water Management, Volume 188
      Author(s): Jalal Shiri
      Accurate estimation of the reference evapotranspiration (ETo ) is needed in water resources planning and management, irrigation scheduling and efficient agricultural water management. The FAO56-PM combination model is usually applied as a benchmark model for calculating ETo and calibrating other ETo models. However, the need for large amount of meteorological variables is a major drawback of this model, especially in case of data scarcity. Therefore, application of ETo models relying on fewer meteorological parameters, as well as calculating ETo using estimated meteorological variables is recommended in literature. The present paper aims at assessing the performances of different ETo models using the recorded and estimated meteorological parameters and comparing the results with the corresponding gene expression programming (GEP) models (based on the same input parameters of the employed ETo models) in hyper-arid regions. Daily meteorological parameters from 5 hyper-arid locations of Iran (covering a period of 12 years) were used. The commonly used Hargreaves (HG), Priestley-Taylor (PT), Turc (Tr) and Kimberly-Penman (KP, for alfalfa reference crop) were established and calibrated using both the recorded and estimated solar radiation, relative humidity, and wind speed data. The obtained results revealed that the GEP models outperform the corresponding empirical and semi-empirical models in all three studied categorizes (temperature/humidity-, radiation-, and combination-based approaches). The results also showed that the calibrated PT (original) and Tr (with estimated relative humidity) models gave the most accurate results among the related groups.

      PubDate: 2017-04-23T03:30:59Z
      DOI: 10.1016/j.agwat.2017.04.009
      Issue No: Vol. 188 (2017)
  • Determinants of cotton farmers’ irrigation water management in arid
           Northwestern China
    • Authors: Til Feike; Ling Yee Khor; Yusuyunjiang Mamitimin; Nan Ha; Lin Li; Nurbay Abdusalih; Haifeng Xiao; Reiner Doluschitz
      Pages: 1 - 10
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): Til Feike, Ling Yee Khor, Yusuyunjiang Mamitimin, Nan Ha, Lin Li, Nurbay Abdusalih, Haifeng Xiao, Reiner Doluschitz
      To combat China’s water crisis tremendous research efforts are undertaken aiming at the improvement of water management in cotton production, which is the major consumer of the scarce water resources in arid Northwestern China. In recent years extensive field experiment based research strongly enhanced the theoretical knowledge of optimal water management in cotton production. However, farmers’ actual irrigation water productivity remains low. To fill the critical void the present study aims at increasing the understanding of Chinese cotton farmers’ actual irrigation water management. The northwestern Chinese Aksu-Tarim Region was selected as a hot-spot of water scarcity in China, where around 60% of total sown crop land are cultivated with cotton. The increasing overuse of scarce surface water resources for irrigation not only leads to severe ecological degradation, but also increases competition among water users triggering the expansion of groundwater exploitation. Based on primary survey data of 228 cotton producing farm households we firstly analyze the production factors determining farmers’ yield and irrigation water productivity (IWP). Apart from soil salinity and unbalanced fertilization, which negatively affect yield and IWP, especially the applied irrigation method (drip vs. flood irrigation) and installation of a groundwater well were identified as major determinants. Secondly, we apply logistic regression to evaluate which household and farm characteristics determine the irrigation method and installation of groundwater well. We find that farm size, crop types and cropping intensity determine the use of drip irrigation. We furthermore find that the installation of well is largely related to marginalization, with farm families of ethnic minorities, remote farms and lower educated families being more likely to install wells. The findings of our study can help policymakers in devising strategies for improving irrigation water productivity, while reducing groundwater degradation in the study region and similar arid production regions in the world.

      PubDate: 2017-04-01T13:38:08Z
      DOI: 10.1016/j.agwat.2017.03.012
      Issue No: Vol. 187 (2017)
  • Determining pomegranate water and nitrogen requirements with drip
    • Authors: James E. Ayars; Claude J. Phene; Rebecca C. Phene; Suduan Gao; Dong Wang; Kevin R. Day; Donald J. Makus
      Pages: 11 - 23
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): James E. Ayars, Claude J. Phene, Rebecca C. Phene, Suduan Gao, Dong Wang, Kevin R. Day, Donald J. Makus
      Despite being an ancient crop there is limited knowledge on the water and nitrogen (N) requirements of pomegranate. We conducted research at the University of California, Kearney Agricultural Research and Extension Center (KARE) to determine the water and N requirements of a developing pomegranate orchard. Pomegranate trees (Punica granatum L. var. Wonderful) were planted in 2010. The irrigation treatments were surface drip irrigation (DI) and subsurface drip irrigation (SDI) with three N sub-treatments (N application rates of 50, 100, and 150% of current practice) and 5 replications in split-plot design. A weighing lysimeter located in the experimental field was used to automatically irrigate the orchard after 1.0mm of measured crop water use. The trees received uniform application of fertilizers and water during the first two years of growth to insure uniform stand establishment prior to beginning the experiment. The pH of the irrigation water was maintained at 6.5±0.5 by injection of N as urea sulfuric acid (US-10; 10% N). Differential N treatments were started in 2012 and continued through the end of the project. Phosphorus (PO4–P) was continuously injected during irrigation and potassium (K2T) was injected weekly. We report the results of the study from 2013 to 2015. From 2013 to 2015 the applied N ranged from 62 to 332kg/ha and the total yields ranged from 33,144 to 57,769kg/ha. There were no statistical differences in yield within any year related to total applied N. The yearly applied irrigation water increased as the plant size increased. The total water requirement is approximately 952mm and the maximum daily water use was 10.5mm. The DI irrigation application went from 645mm to 932mm and the SDI application increased from 584mm to 843mm from 2013 to 2015. A fifth order polynomial was fitted to the crop coefficient using the 2015 data. The use of SDI resulted in lower weed pressure in the SDI plots than in the DI irrigated plots in all three years. High frequency irrigation resulted in nitrate being managed within the soil profile to a depth of 1.5 m by minimizing deep percolation losses to the groundwater. While the yields were higher in the SDI than the DI system they were not statistically different. Although there were some differences in N content in tree leaves and fruit peels, there were no differences in fruit arils among N rates. The N requirement is in the range of 62–112kg/ha (109–198g/tree) for a mature pomegranate orchard and will ultimately depend on the planting density.

      PubDate: 2017-03-25T13:19:03Z
      DOI: 10.1016/j.agwat.2017.03.007
      Issue No: Vol. 187 (2017)
  • Agricultural water allocation strategies along the oasis of Tarim River in
           Northwest China
    • Authors: Yang Yu; Ruide Yu; Xi Chen; Guoan Yu; Miao Gan; Markus Disse
      Pages: 24 - 36
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): Yang Yu, Ruide Yu, Xi Chen, Guoan Yu, Miao Gan, Markus Disse
      Efficient reallocation of existing water supply is gaining importance as demand grows and competitions among users intensify. In extremely arid regions, where deficit irrigation needs to be applied, management decisions on agricultural water allocation are often onerous tasks due to the confliction among water users. This paper presents a hydrological modeling approach to assist decision-makers and stakeholders to resolve potential water-sharing conflicts among water users. We combine the land use map with water distribution methods to solve the water allocation problems in a large basin scale. The model is tested and applied in three steps: (i) calibration and validation of water supply and demand along the Tarim River with a combined hydrological and groundwater model, (ii) developing climate change scenarios, (iii) optimizing agricultural water allocation for the entire Tarim River Basin for these scenarios and deriving of conclusions. The comprehensive management of farmland areas and water distribution strategies are investigated in the model scenarios. The results of these assessments provide opportunities for substantial improvement on water allocation and water right. The access of a user to use the water efficiently should be guaranteed, especially in the lower reaches of the river in the arid land. In practice, the hydrological model assists on decision-making for water resource management in a large river basin, and incentive to utilize water use in an efficient manner.

      PubDate: 2017-03-25T13:19:03Z
      DOI: 10.1016/j.agwat.2017.03.021
      Issue No: Vol. 187 (2017)
  • Effects of increased seawater salinity irrigation on growth and quality of
           the edible halophyte Mesembryanthemum crystallinum L. under field
    • Authors: Giulia Atzori; Arjen C. de Vos; Marc van Rijsselberghe; Pamela Vignolini; Jelte Rozema; Stefano Mancuso; Peter M. van Bodegom
      Pages: 37 - 46
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): Giulia Atzori, Arjen C. de Vos, Marc van Rijsselberghe, Pamela Vignolini, Jelte Rozema, Stefano Mancuso, Peter M. van Bodegom
      Saline agriculture may answer to the declining availability of fresh water and to the worldwide expanding area of salinized soils by exploiting seawater and salt-affected soils for sustainable food production. Potential salt tolerant crops can be found among edible halophytes. Moreover, plants growing in saline environments are often associated with an enhanced endogenous concentrations of high-nutrient compounds. Mesembryanthemum crystallinum L. provides an interesting perspective in becoming a salt-tolerant and high-value crop at saline conditions, but has never been tested at representative agricultural conditions. This study aimed at assessing the effects of increasing levels of seawater salinity irrigation (electrical conductivity: 2, 4, 8, 12, 16, 20, and 35dSm−1) on growth and productive performance in a field experiment. Also, impacts of salinity on the functional value of edible leaves were evaluated by investigating the mineral elements, carotenoids, soluble sugars, and phenolic concentrations, along with antioxidant activity. Our results demonstrate that none of the salinity treatments negatively affected M. crystallinum biomass production. Furthermore, increased salinity extended the vegetative stage, leading to one extra month of harvest compared to non-saline conditions. Juvenile edible leaves' biomass, succulence and calcium concentrations even increased with increasing salinity. No differences were assessed in the phenolics concentration and antioxidant activity of high salinity treatments plants compared to the control. This paper demonstrates the perspective to cultivate M. crystallinum in saline agriculture, up to EC of 20–35dSm−1, or perhaps even higher, since we did not identify a threshold of biomass reduction. Only the Na+ concentration in the edible leaves could constitute a health concern or allow it acting as a natural salt substitute. This excellent performance in combination with the appreciated taste and its glistening appearance, may pave the way for use of the ice plant as high-value saline crop.

      PubDate: 2017-03-25T13:19:03Z
      DOI: 10.1016/j.agwat.2017.03.020
      Issue No: Vol. 187 (2017)
  • Financial assessment of adopting irrigation technology for plant-based
           regulated deficit irrigation scheduling in super high-density olive
    • Authors: Gregorio Egea; José E. Fernández; Francisco Alcon
      Pages: 47 - 56
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): Gregorio Egea, José E. Fernández, Francisco Alcon
      Hedgerow orchards with high plant densities, or super high-density (SHD) orchards, are considered to be amongst the most profitable management systems for most fruit-tree species. Regulated deficit irrigation (RDI) strategies are recommended for SHD olive orchards, especially when scheduled from automatic and continuous measurements of plant water stress. There is a lack of information, however, on the profitability of this approach. In this work we analysed the financial feasibility of using three different systems for monitoring water stress in an ‘Arbequina’ SHD olive orchard under a RDI strategy recommended for the experimental area (SW Spain). The systems were based on sap flow (SF), trunk diameter variation (TDV) and leaf turgor pressure (TP) related measurements. We first compared their equivalent annual cost (EAC), resulting the TP based technology as that with the greatest potential to be adopted by farmers. We then used Discounted Cash Flow Analysis (DCFA) to compare the financial feasibility of an RDI treatment scheduled from TP related measurements and providing 45% of the crop water needs (45RDITP) with both a similar treatment but scheduled with the crop coefficient approach (45RDICC) and a fully irrigated (FI) treatment. Our results from two irrigation seasons demonstrated that the 45RDI strategy guarantees the profitability of SHD olive orchards in the long-term, with both 45RDICC and 45RDITP showing positive Net Present Value and Internal Rate of Return above the interest on capital. All the financial indicators suggested higher financial performance of 45RDITP as compared to 45RDICC, but differences were not significant, likely because of the high variability among replicates. The financial impact of Common Agricultural Policy payments as well as varying olive oil and irrigation water prices on the irrigation treatments was discussed.

      PubDate: 2017-03-25T13:19:03Z
      DOI: 10.1016/j.agwat.2017.03.008
      Issue No: Vol. 187 (2017)
  • Evaluation of DRAINMOD-DSSAT simulated effects of controlled drainage on
           crop yield, water balance, and water quality for a corn-soybean cropping
           system in central Iowa
    • Authors: Lamyaa M. Negm; Mohamed A. Youssef; Dan B. Jaynes
      Pages: 57 - 68
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): Lamyaa M. Negm, Mohamed A. Youssef, Dan B. Jaynes
      Controlled drainage (CD) has been identified as a sustainable management practice whereby more soil water can be conserved and less nutrients are leached; alongside its potential benefit of alleviating drought stress and increasing yield. More than 12 million hectare of cropland in the US Midwest are suitable for implementing CD; however, the effectiveness of the practice can vary across the region with the variation in environmental conditions and management practices. The main objective of this study is to evaluate the performance of the integrated agro-ecosystem model; DRAINMOD-DSSAT, for simulating the effects of CD on drainage flow, nitrogen losses via drainage water and crop yield. Herein, we utilized a 4-yr dataset (2006–2009) that was collected from a corn–soybean cropping system near Story City, Iowa. This site was artificially drained under free drainage (FD) and CD treatments. The model was calibrated using the data collected from the FD plots, and validated for the CD plots. DRAINMOD-DSSAT predictions of drainage flow and nitrate-nitrogen (NO3-N) losses were in good agreement with measured values under FD and CD, with the former treatment showed slightly better performance. The modeling efficiencies (NSE’s) for simulating monthly drainage flows were 0.81 and 0.60 for FD and CD, respectively. Monthly NO3–N mass losses were simulated with NSE’s of 0.76 and 0.66 for FD and CD, respectively. DRAINMOD-DSSAT well simulated CD-induced percent reductions in annual drainage flow (measured=24.6%, simulated=27.1%), and NO3-N losses (measured=34.8%, simulated=33.5%). Low percent error (PE) values were associated with the model predictions of corn yields (−1.3≤PE≤1.3) and soybean yields (−6.0≤PE≤12.6). Overall, results obtained from this relatively short-term modeling study demonstrated the potential use of DRAINMOD-DSSAT as a management design tool. Yet, further model testing CD effectiveness under different conditions is critically needed to establish a higher credibility in model predictions and to allow for further model improvement and expansion.

      PubDate: 2017-03-25T13:19:03Z
      DOI: 10.1016/j.agwat.2017.03.010
      Issue No: Vol. 187 (2017)
  • Effect of surge flow and alternate irrigation on the irrigation efficiency
           and water productivity of onion in the semi-arid areas of North Ethiopia
    • Authors: Mulubrehan Kifle; T.G. Gebremicael; Abbadi Girmay; Teferi Gebremedihin
      Pages: 69 - 76
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): Mulubrehan Kifle, T.G. Gebremicael, Abbadi Girmay, Teferi Gebremedihin
      The study was conducted in the semi-arid areas of northern Ethiopia with the objective of evaluating the effect of surge flow and alternate irrigation on irrigation performance indicators, water use efficiency and crop yield. The experiment consists of two factors, irrigation systems (alternate furrow (Af) and conventional furrow (CF)) and irrigation flow methods (continuous (C), Surge 1 (S1), Surge 2 (S2), and Surge 3 (S3)). Eight treatment combinations replicated three times were arranged in a factorial randomized complete block design. Onion crop was used as indicator crop for the experiment because of its dominant and cash crop in the region. The result of this experiment indicated that the interaction effect of the irrigation system and irrigation flow methods did not show statistically significant difference on the performance indicators, crop yield and water use efficiency. The irrigation system (Af and CF) as a factor has not significant effect on yield of onion. However, the irrigation flow methods (C, S1, S2 and S3) were significantly affected the irrigation performance indicators (application efficiency, distribution uniformity, deep percolation and tail water runoff losses) and likewise, irrigation water use efficiency and yield of onion were significantly different. Higher crop yield (13208kg/ha), water use efficiency (1.96–2.55kg/m3), application efficiency (52.9–58.7%) and distribution uniformity (81.4–86.2%) were obtained from both surge flow and alternate irrigation as compared to continuous flow and conventional furrow irrigation (every furrow water application) which was recorded less 10142kg/ha, 1.36–1.65kg/m3, 44–54.7%, 67.1–79.6%, respectively. The result of this study explicitly showed that demonstration of these irrigation methods can enhance the poor water management practices in the semi-arid areas of Ethiopia and elsewhere in the world with limited water resources and similar soil characteristics. The authors of this paper recommend the farmers, irrigation experts, water resources managers and decision makers in the region to apply those techniques for improving water use efficiency.

      PubDate: 2017-03-25T13:19:03Z
      DOI: 10.1016/j.agwat.2017.03.018
      Issue No: Vol. 187 (2017)
  • Phosphorus fractions in discharges from artificially drained lowland
           catchments (Warnow River, Baltic Sea)
    • Authors: Monika Nausch; Jana Woelk; Petra Kahle; Günther Nausch; Thomas Leipe; Bernd Lennartz
      Pages: 77 - 87
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): Monika Nausch, Jana Woelk, Petra Kahle, Günther Nausch, Thomas Leipe, Bernd Lennartz
      Understanding phosphorus (P) dynamics, from inland sources to the sea, is essential for developing strategies to reduce P loads. In this study, we examined concentrations, fractions, and association of P with other elements at a tile-drain outlet, the adjacent ditch and brook, further downstream from the brook, and in the river itself. The study was conducted in a sub-basin of the Warnow River catchment from 1 November 2013 to 30 April 2014 covering a mild and dry winter. Total phosphorus (TP) concentrations were lowest at the tile-drain effluent and increased in the ditch and brook, as a result of elevated dissolved reactive phosphorus (DRP), particulate reactive (PRP) and organic (POP) phosphorus. Dissolved organic phosphorus (DOP) concentrations remained constant. Further increase of TP along the brook and in the river reflected the increase in DRP+DOP along the first 2.5km and the doubling of PRP along the 6.5km thereafter. In the river, phytoplankton growth transformed P into POP in early spring. Total loads of DRP, PRP+POP, and DOP emitted during the study period were 4.3–5.6, 3–7, and 1–2gha−1 respectively, with an increasing tendency downstream. Despite their low P content (0.7–3.9%), clay minerals and Fe(hydr)oxides particles were the most important carriers because they formed 68–90% of all P-containing particles. A shift from Ca-phosphate to Fe-phosphate occurred from winter to spring and there was a variation in composition of P-containing particles along the flow course. Our results underline the importance of particulate P in discharge and show that the brook Zarnow following the drain outlet and the ditch is a location of P-enrichment and modification probably due to other inputs. The entire flow course has to be considered to assess nutrient inputs from agricultural land because P-composition and loads are changing in time and space.
      Graphical abstract image

      PubDate: 2017-03-25T13:19:03Z
      DOI: 10.1016/j.agwat.2017.03.006
      Issue No: Vol. 187 (2017)
  • Applications of organic manure increased maize (Zea mays L.) yield and
           water productivity in a semi-arid region
    • Authors: Xiaolin Wang; Yuanyuan Ren; Suiqi Zhang; Yinglong Chen; Nan Wang
      Pages: 88 - 98
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): Xiaolin Wang, Yuanyuan Ren, Suiqi Zhang, Yinglong Chen, Nan Wang
      Organic manure application has been neglected in recent years, reflecting the rapid replacement with synthetic fertilizer. Exploration of the restorative effect of organic manure on the soil fertility, quality and sustainable productivity is urgently needed. A 4-year field experiment (2011–2014) investigated variation of grain yield, soil water-nutrient content and plant growth in a local cultivar (Zheng Dan 958) of maize (Zea mays L.) at three planting densities with extra organic manure application in a semi-arid region of Northwestern China. Soil water content in 0–50cm and below 150cm soil profile was maintained stably at 25% and 18% under organic manure application over four consecutive years, and soil water use in the depth of 50–150cm was improved. Organic manure helped residual soil nutrient mineralization after harvest with 25%, 198% and 41% increases in total nitrogen (N), available phosphorus (P) and soil organic matter (SOM) over three years respectively. Adequate content of N, P and SOM after maize harvest played an important role for stable high yield in the next season. Consequently, the biomass allocation into shoot and grains was optimized and presented as a slight increase in harvest index (HI). Based on the improvement of water-nutrient status in manured soil, maize water productivity (WP) increased by 3–8%, which positively associated with the yield increase by 5–10% at high planting density. Organic manure could be used to improve soil environment, promote yield and WP in maize in dryland agriculture.

      PubDate: 2017-03-25T13:19:03Z
      DOI: 10.1016/j.agwat.2017.03.017
      Issue No: Vol. 187 (2017)
  • Impact of irrigation on plant growth and development of white cabbage
    • Authors: S.J. Seidel; S. Werisch; N. Schütze; H. Laber
      Pages: 99 - 111
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): S.J. Seidel, S. Werisch, N. Schütze, H. Laber
      It is widely known that an optimal irrigation water supply is a key to high horticultural productivity, efficient water use, and the reduction of off-site effects due to percolation of excess water. To promote better agronomic practices in irrigated horticulture, three different irrigation scheduling approaches based on soil water balance calculations, soil water potential measurements (sensor-based), and crop growth model simulations, were evaluated in a two-year field experiment. The experiments were conducted with white cabbage on a loamy sand soil near Dresden, Germany. The results show that sensor-based irrigation, at a soil water potential of −250hPa measured at a soil depth of 30cm, achieved high yields with moderate to low irrigation water inputs. Irrigation scheduling based on soil water balance calculations led to unproductive over-irrigation due to overestimated crop coefficients, which highlight the need for more accurate estimates of these coefficients. Simulation-based irrigation scheduling resulted in acceptable water productivities but can only be recommended to farmers to some extent because it requires a robust crop model calibration. Analysis of the plant development indicates that maintenance of field capacity until the end of head formation is favorable. Drought stress lead to reduced plant heights, leaf area indices and head yields. Furthermore, the results show that early drought stress effects can be compensated by an appropriate water supply in later growing stages.

      PubDate: 2017-03-25T13:19:03Z
      DOI: 10.1016/j.agwat.2017.03.011
      Issue No: Vol. 187 (2017)
  • Soil water and salt affect cotton (Gossypium hirsutum L.) photosynthesis,
           yield and fiber quality in coastal saline soil
    • Authors: He Zhang; Duansheng Li; Zhiguo Zhou; Rizwan Zahoor; Binglin Chen; Yali Meng
      Pages: 112 - 121
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): He Zhang, Duansheng Li, Zhiguo Zhou, Rizwan Zahoor, Binglin Chen, Yali Meng
      To target the favorable conditions for cotton growth in coastal saline soil, a two year field experiment was conducted in 2013 and 2014 by setting various environments for soil water and salt with different groundwater depths (0.6, 1.0, 1.4, 1.8, 2.2, 2.6m in 2013 and 0.4, 0.8, 1.2, 1.6, 2.0, 2.4m in 2014). Results showed that (1) in relatively arid year of 2013, soil exhibited normal soil-relative water content with high salt and mild drought with moderate salt in the optimal groundwater depths of 1.4m and of 1.8m (1.87m for fitting), respectively. In relatively humid year of 2014, soil displayed normal soil-relative water content with low salt in the optimal groundwater depths of 1.6m and 2.0m (1.73m for fitting). (2) Net photosynthesis, cotton yield and fiber quality all approached to the highest values in the optimal treatments. The reduction in net photosynthetic rate was mainly due to non-stomatal restriction in the treatment of 0.6m in 2013 and 0.4m in 2014. Meanwhile, in other treatments stomatal restriction was the main factor for photosynthesis limitations. As compared to optimal groundwater depths, the seed cotton yield was dropped by 73.9%, 21.4% and 71.4%, 21.4% under groundwater depths of 0.6m, 2.6m in 2013 and of 0.4m, 2.4m in 2014, respectively. Reduced boll number played a critical role to decrease seed cotton yield. In summary, the favorable soil-relative water contents for 0–20 and 20–40cm soil depth were 54.68%–65.14% and 69.14%–79.13% in dry year of 2013 and 67.18%–69.39% and 73.00%–77.92% in humid year of 2014, respectively; similarly, electrical conductivity of a 1:5 distilled water for 0–20 and 20–40cm soil depth was recorded as 0.92–1.20dSm−1 and 0.70–0.95dSm−1 in 2013, while 0.28–0.32dSm−1 and 0.45–0.51dSm−1 in 2014, respectively.

      PubDate: 2017-04-01T13:38:08Z
      DOI: 10.1016/j.agwat.2017.03.019
      Issue No: Vol. 187 (2017)
  • Seasonal variation of reference evapotranspiration and Priestley-Taylor
           coefficient in the eastern Free State, South Africa
    • Authors: Mphethe I. Tongwane; Michael J. Savage; Mitsuru Tsubo; Mokhele E. Moeletsi
      Pages: 122 - 130
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): Mphethe I. Tongwane, Michael J. Savage, Mitsuru Tsubo, Mokhele E. Moeletsi
      Estimation of reference evapotranspiration (ETo) is crucial in crop production practices and other hydrological processes. The hourly FAO-56 Penman-Monteith (EToPM) method was used to calculate ETo at Bergville, Bethlehem and Harrismith in the eastern Free State, South Africa. Priestley-Taylor evapotranspiration coefficients (PTc) were estimated using EToPM and equilibrium evapotranspiration. The study establishes that for the mountainous semi-arid areas, aerodynamic conditions are major contributors of evapotranspiration. The aerodynamic component of EToPM is generally a dominant contributor varying between 50% and 70% of the total EToPM depending on the season and location. Dry and windy atmospheric conditions that reach their highest levels during the spring season cause water vapour pressure deficit to be a parameter with greater influence on ETo. The study further shows that the impact of solar irradiance on ETo decreases with altitude in the study area. More than 87% of EToPM from aerodynamic resistance is experienced during daytime. Agricultural water resources management activities need to consider the importance of nocturnal EToPM which contributes between 10–14% of total daily ETo depending on the station. Geometry of a surface affects total solar irradiance received at a place and the associated ETo. The commonly used average Priestley-Taylor constant of 1.26 under-estimates evaporation rates in the semi-arid environments. This study shows that the coefficients are highly variable during winter and spring, less variable in autumn, and that topoclimate has a significant impact on the PTc variability. This variability reflects a direct influence that the dry atmospheric environments of the semi-arid regions have on PTc, which is a limitation of the use of the 1.26 coefficient.

      PubDate: 2017-04-01T13:38:08Z
      DOI: 10.1016/j.agwat.2017.03.013
      Issue No: Vol. 187 (2017)
  • Seasonal water quality changes in on-farm water storage systems in a
           south-central U.S. agricultural watershed
    • Authors: Juan D. Pérez-Gutiérrez; Joel O. Paz; Mary Love M. Tagert
      Pages: 131 - 139
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): Juan D. Pérez-Gutiérrez, Joel O. Paz, Mary Love M. Tagert
      The objective of this study was to investigate the ability of on-farm water storage (OFWS) systems to mitigate off-site nutrient movement in a south-central U.S. agricultural watershed. We examined the seasonal water quality changes in an OFWS system by measuring several physical and chemical constituents at multiple sampling points throughout the system. Water quality sampling occurred every three weeks during the growing season and every six weeks during the dormant season from February 2012 to December 2014. The collected data were grouped into four seasons and then analyzed using boxplots along with the Wilcoxon and Kruskal-Wallis rank-sum tests for detecting changes in nutrient concentrations. Significant water quality changes were observed in the OFWS system by season and nutrient species, indicating a variation in downstream nutrient reduction with season. The in-ditch median removal efficiency, from the center of the tailwater recovery ditch to the outlet, was 54% during winter and 50% during spring for NO3-N; 60% during spring for NH3-N; 26% during autumn and 65% during winter for ortho-P; and 31% during winter and 10% during spring for TP. The in-pond median concentration removal efficiency was ∼77% during summer for NO3-N, while the concentration remained stable during winter, spring and autumn; 53% from winter to spring and 58% from spring to summer for NH3-N; 70% from winter to spring for ortho-P, while remaining stable during the other seasons; and 28% from winter to spring and 55% from spring to summer for TP. Our results support the hypothesis that OFWS systems could mitigate downstream nutrient-enrichment pollution, especially during spring. The results obtained from this study offer a better insight into the behavior of OFWS systems and help enhance the management of agroecosystems from an ecological and hydrological perspective for water quality pollution control and water resource conservation.

      PubDate: 2017-04-01T13:38:08Z
      DOI: 10.1016/j.agwat.2017.03.014
      Issue No: Vol. 187 (2017)
  • Reflectance-based crop coefficients REDUX: For operational
           evapotranspiration estimates in the age of high producing hybrid varieties
    • Authors: Isidro Campos; Christopher M.U. Neale; Andrew E. Suyker; Timothy J. Arkebauer; Ivo Z. Gonçalves
      Pages: 140 - 153
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): Isidro Campos, Christopher M.U. Neale, Andrew E. Suyker, Timothy J. Arkebauer, Ivo Z. Gonçalves
      Methodologies based on earth observation remote sensing allow for a precise estimation of actual water requirements for irrigated crops across large areas. In spite of the many number of experiments using or analyzing the relationship between the basal crop coefficient (Kcb) and the soil adjusted vegetation index (SAVI) for maize, the development of new maize hybrid varieties with modifications related to canopy architecture suggest a possible change of the leaf area index (LAI) for maximum Kcb and its relationship with the SAVI or other vegetation indices. In addition, we noted a lack of analysis of these relationships for cultivated soybean. The objective of this paper is to analyze the Kcb, SAVI and LAI relationships in maize and soybean based on the non-linear relationships proposed by Choudhury et al. (1994). In addition, we propose a modification of the Choudhury et al. (1994) approach based on field-based experimental evidence of a minimum Kcb greater than 0. For sites with limited field data, we also analyze the utility of a simple linear regression based on the Kcb and SAVI values for bare soil and maximum Kcb values. The resulting Kcb-SAVI relationships are assimilated into a remote sensing based soil water balance model. The results of the model are analyzed in terms of irrigation requirements and crop evapotranspiration (ETa) for 11 growing seasons in two fields cultivated with irrigated and rain-fed maize and soybean in eastern Nebraska. Comparisons of measured and modelled ETa values indicate a good agreement, with RMSE lower than 0.7mmd−1 for weekly averaged values. The comparison of actual irrigation applied and irrigation requirements indicate the central pivot systems could not supply adequate water in some growing seasons with higher demands.

      PubDate: 2017-04-01T13:38:08Z
      DOI: 10.1016/j.agwat.2017.03.022
      Issue No: Vol. 187 (2017)
  • Optimizing preplant irrigation for maize under limited water in the High
    • Authors: I. Kisekka; A. Schlegel; L. Ma; P.H. Gowda; P.V.V. Prasad
      Pages: 154 - 163
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): I. Kisekka, A. Schlegel, L. Ma, P.H. Gowda, P.V.V. Prasad
      Due to inadequate irrigation capacity, some farmers in the United States High Plains apply preplant irrigation to buffer the crop between irrigation events during the cropping season. The purpose of the study was to determine preplant irrigation amount and irrigation capacity combinations that optimize yield, water productivity, and precipitation use efficiency (PUE) and minimize soil water evaporation losses prior to planting. The CERES-Maize model embedded in the RZWQM2 model in combination with long-term climatic data from 1986 to 2014 for southwest Kansas were used for this research. Experimental data from 2006 to 2009 was used to calibrate and validate the model. Model performance was satisfactory with high index of agreement (IA>0.88). Relative root mean square error (RRMSE) ranged between 4.5% and 27%. Under very limited irrigation capacity (2.5mm/day), applying 75–100mm of preplant irrigation produced median yields that were 10–17% higher than not applying preplant irrigation. However, even at limited irrigation capacity the benefit of preplant irrigation were only realized if the seasonal yield potential was in the range of 6000 to 10,000kg/ha corresponding to years with normal seasonal rainfall. Irrigation capacity had a stronger effect on maize grain yield compared to preplant irrigation amount. Preplant irrigation increased ET and transpiration under 2.5mm/day irrigation capacity. Preplant irrigation amount did not have a substantial impact on water productivity at high and moderate irrigation capacity but had second order dominant effect under limited irrigation capacity. At low irrigation capacity (2.5mm/day) increasing preplant irrigation increased median PUE up to 18% although the effect was second order dominant. Negligible water losses through deep percolation from 2.4m soil profile were simulated. Increasing preplant irrigation resulted in significantly higher soil water evaporation losses prior to planting at all irrigation capacities. Overall preplant irrigation is beneficial under very limited irrigation capacity but is not necessary under sufficient irrigation capacity in most years. The decision to apply preplant irrigation should be evaluated and implemented carefully in combination with other agricultural water management technologies and strategies such as soil water monitoring, drip irrigation, and residue management.

      PubDate: 2017-04-01T13:38:08Z
      DOI: 10.1016/j.agwat.2017.03.023
      Issue No: Vol. 187 (2017)
  • Institutional and management implications of drip irrigation introduction
           in collective irrigation systems in Spain
    • Authors: M. Ortega-Reig; C. Sanchis-Ibor; G. Palau-Salvador; M. García-Mollá; L. Avellá-Reus
      Pages: 164 - 172
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): M. Ortega-Reig, C. Sanchis-Ibor, G. Palau-Salvador, M. García-Mollá, L. Avellá-Reus
      This work focuses on the transformation occurred with the shift from surface to drip irrigation, looking at three collective irrigation systems in Valencia (Spain). The extension of drip irrigation over areas previously irrigated by systems of gravity channels entails a process of change and transformation of institutions and organizations managing irrigation. We analyze the main management changes occurred and how farmers adapt to the new technology. In order to assess these changes, interviews were conducted with farmers and managers of Water User Associations. Drip irrigation implementation policies result in unforeseen consequences, paradoxes and challenges for collective drip irrigation management. In the three cases, drip irrigation and automation has contributed to the centralization of decision-making. Besides, farmers and managers have also developed irrigation and fertigation strategies to adapt to the new technology. When some of these new operating procedures are applied, farmers obtain results closer to their own goals, but not necessarily linked to the virtues frequently attributed to drip systems.

      PubDate: 2017-04-01T13:38:08Z
      DOI: 10.1016/j.agwat.2017.03.009
      Issue No: Vol. 187 (2017)
  • Crop evapotranspiration calculation using infrared thermometers aboard
           center pivots
    • Authors: Paul D. Colaizzi; Susan A. O’Shaughnessy; Steve R. Evett; Ryan B. Mounce
      Pages: 173 - 189
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): Paul D. Colaizzi, Susan A. O’Shaughnessy, Steve R. Evett, Ryan B. Mounce
      Irrigation scheduling using remotely sensed surface temperature can result in equal or greater crop yield and crop water use efficiency compared with irrigation scheduling using in-situ soil water profile measurements. Crop evapotranspiration (ETc) is useful for irrigation scheduling, and can be calculated using surface temperature. Recent advances in wireless infrared thermometers (IRTs) have made surface temperature measurement a viable alternative to in-situ soil water profile measurements, and wireless IRTs are practical for deployment aboard moving irrigation systems, such as center pivots. However, ETc calculation has not been tested using IRTs aboard center pivots in conjunction with recent advances in a two-source energy balance (TSEB) model. We compared daily ETc calculated by a TSEB model to daily ETc estimated by a simple soil water balance (SSWB), where the SSWB used volumetric soil water measured by a field calibrated neutron probe to the 2.4-m depth. Crops included two seasons each of corn (Zea mays L.), cotton (Gossypium hirsutum L.), and grain sorghum (Sorghum bicolor L.) at Bushland, Texas, USA. Discrepancies of TSEB vs. SSWB daily ETc were similar for each crop and season, and had root mean squared error from 1.5 to 1.8mm per day, mean absolute error from 1.1 to 1.5mm per day, and mean bias error from −0.51 to 0.63mm per day. A sensitivity analysis was conducted for daily evaporation (E), daily transpiration (T), and ETc calculated by the TSEB model. These were most sensitive to radiometric surface temperature, air temperature, the reference temperature used in time scaling (i.e., to convert instantaneous to daily E, T, and ETc), and incoming solar irradiance. Because over half of the irrigated area in the USA is now by center pivot, ETc calculated using IRTs aboard center pivots will be useful to maintain or increase crop water productivity.

      PubDate: 2017-04-01T13:38:08Z
      DOI: 10.1016/j.agwat.2017.03.016
      Issue No: Vol. 187 (2017)
  • Antropogenic input of nitrogen and riverine export from a Mediterranean
           catchment. The Celone, a temporary river case study
    • Authors: Anna Maria De Girolamo; Raffaella Balestrini; Ersilia D’Ambrosio; Giuseppe Pappagallo; Elisa Soana; Antonio Lo Porto
      Pages: 190 - 199
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): Anna Maria De Girolamo, Raffaella Balestrini, Ersilia D’Ambrosio, Giuseppe Pappagallo, Elisa Soana, Antonio Lo Porto
      In a catchmnent, nitrogen (N) export from terrestrial ecosystems to rivers is controlled by the hydrological processes and N balance. In the present paper, the soil system N budget and riverine export were quantified in a Mediterranean watershed, the Celone (South-East, Italy). The study area (72km2) consists of agricultural land (70%) and deciduous forests with three small residential areas. Major N inputs derived from fertilizers and animal manure, corresponding for the whole watershed area to 68 and 12kgNha−1 yr−1, respectively. N input from point sources was 1% of total input and atmospheric depositions measured in a gauging station near the study area was quantified in ∼6kgNha−1 yr−1. Crop N uptake was the main N output from agricultural land; it was estimated in ∼37kgNha−1 yr−1 by using data on crop yields provided by local farmers. Total flux of N in surface water was quantified for a year at the outlet of the study area by using continuous measures of flow and discrete measures of N concentrations carried out with a different frequency during the normal and low flow and when floods occurred. The hydrological regime of the stream, which is a temporary river, plays an important role in N transport. Water quality was found to vary considerably through the year in terms of both nutrient concentrations and loads. Riverine N export was quantified in 41% of total N input, and it was mainly transported during flood events, ∼60% of the annual load was delivered during floods occurred in 38 days. Organic nitrogen and nitrate were the main N forms in surface water, and the contribution per hectare was about 24 and 14kgN, respectively. On a yearly basis, the difference between N inputs and outputs including riverine export was estimated in about 4kgNha−1 yr−1 for the whole watershed area. This amount partly accumulates in soils in different N forms and the remaining part, mainly in form of nitrate, percolates through unsaturated soil towards groundwater. This study reports an important analysis of N pollution in a Mediterranean watershed with a temporary river system and limited data availability. Data acquisition and handling have proved to be an important challenge to overcome in N balance quantification. The results and the methodology of the present work can be useful for understanding nitrogen loss dynamics and for functional water management and land use planning.
      Graphical abstract image

      PubDate: 2017-04-01T13:38:08Z
      DOI: 10.1016/j.agwat.2017.03.025
      Issue No: Vol. 187 (2017)
  • Quantification of wheat crop evapotranspiration and mapping: A case study
           from Bhiwani District of Haryana, India
    • Authors: Kishan Singh Rawat; Anju Bala; Sudhir Kumar Singh; Raj Kumar Pal
      Pages: 200 - 209
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): Kishan Singh Rawat, Anju Bala, Sudhir Kumar Singh, Raj Kumar Pal
      In this study an attempt has been made to estimate the actual wheat crop evapotranspiration (ETc) by Surface Energy Balance Algorithm (SEBAL) and standardized FAO-Penman-Monteith (FAO-PM) method. Improved knowledge of evapotranspiration (ET) helps in understanding the water balance of any region. The results obtained through measured lysimeter, SEBAL and PM method were evaluated through statistical performance measure tests. ETc estimated from SEBAL was found to correlate significantly as R2 (0.91) with the measured ETc of lysimeter. ETc estimated by SEBAL was also compared with PM ETc with the help of crop coefficient and was found to correlate significantly as R2 (0.85). The other statistical parameters (RMSE=0.56, nRMSE=0.09, MAE=0.26, NRMSE=0.20, R-RMSE=0.27, NSE=1, d=0.87 (≈1)) were also showing a good agreement between SEBAL ETc and PM ETc. The findings of work have suggested that SEBAL model shows a good potential to estimate spatial ETc for the region. Additionally the validation of models results were performed with the analysis of correlation between models ETc and district level wheat production and area under crop of five years. The results of this analysis outline that water availability and good amount of rainfall gives higher wheat yield and resulted into more ETc.

      PubDate: 2017-04-09T13:45:44Z
      DOI: 10.1016/j.agwat.2017.03.015
      Issue No: Vol. 187 (2017)
  • Assessing a crop water stress index derived from aerial thermal imaging
           and infrared thermometry in super-high density olive orchards
    • Authors: Gregorio Egea; Carmen M. Padilla-Díaz; Jorge Martinez-Guanter; José E. Fernández; Manuel Pérez-Ruiz
      Pages: 210 - 221
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): Gregorio Egea, Carmen M. Padilla-Díaz, Jorge Martinez-Guanter, José E. Fernández, Manuel Pérez-Ruiz
      Characterization of the spatio-temporal variability of tree water status is a prerequisite to conducting precise irrigation management in fruit tree orchards. This study assessed the suitability of a crop water stress index (CWSI) derived from high-resolution aerial thermal imagery for estimating tree water status variability in super high density (SHD) olive orchards. The experiment was conducted at a commercial SHD olive orchard near Seville (southwestern Spain), with drip irrigated trees under three irrigation treatments (four plots per treatment in a randomized block design): a full irrigation treatment to replace the crop water needs (ETc) and two regulated deficit irrigation treatments to replace ca. 45% of ETc. Meteorological variables, soil moisture content, leaf water potential, stem water potential and leaf gas exchange measurements were performed along the irrigation season. Infrared temperature sensors (IRTs) installed approximately 1m above the canopies were used to derive the required Non-Water-Stressed Baselines (NWSBs) for CWSI calculation. NWSBs were not common during the growing season, although the seasonal effect could be partly explained with solar angle variations. A thermal camera installed on a mini Remotely Piloted Aircraft System (RPAS) allowed for the recording of high-resolution thermal images on 5 representative dates during the irrigation season. The CWSI values derived from aerial thermal imagery were sensitive to the imposed variations in tree water status within the SHD olive orchard. Among the recorded variables, maximum stomatal conductance showed the tightest correlation with CWSI. We concluded that high-resolution thermal imagery captured from a mini RPAS is a suitable tool for defining tree water status variability within SHD olive orchards.

      PubDate: 2017-04-09T13:45:44Z
      DOI: 10.1016/j.agwat.2017.03.030
      Issue No: Vol. 187 (2017)
  • Water use efficiency of a rice paddy field in Liaohe Delta, Northeast
    • Authors: Yu Wang; Li Zhou; Qingyu Jia; Wenying Yu
      Pages: 222 - 231
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): Yu Wang, Li Zhou, Qingyu Jia, Wenying Yu
      Water use efficiency (WUE) of rice paddy fields is very important because of the increasing demand for crop production and increasing scarcity of water for irrigation. The seasonal dynamics of WUE and their environmental controls were determined in a rice paddy field in Liaohe Delta, Northeast China, based on 2-year period (2013–2014) eddy-covariance flux and meteorological measurements. The annual and growing-season ecosystem water use efficiency (eWUE) of the paddy field were 1.00gCkg−1 H2O and 1.35gCkg−1 H2O (two-year average), respectively. The seasonal variation of eWUE showed an asymmetric single-peak curve. The leaf area index (LAI) was the dominant regulator of evapotranspiration-based WUE; however, the VPD was the most important controlling factor of transpiration-based WUE. The significant positive control of LAI on evapotranspiration-based WUE was likely caused by its strong regulation of the ratio of transpiration (TR) to evapotranspiration (ET). The residual WUE (calculated from the WUE subtracted from the modeled WUE using the relationship between the WUE and LAI) was negatively correlated with net radiation (Rn). The WUE was generally higher under cloudy conditions than under clear conditions. Based on a comparison of the four WUE indicators, the separation of ET to TR and soil evaporation (ES), as well as the incorporation of the nonlinear effect of vapor pressure deficit (VPD) on WUE, would both greatly improve the performances of WUE indicators in rice paddy fields.

      PubDate: 2017-04-09T13:45:44Z
      DOI: 10.1016/j.agwat.2017.03.029
      Issue No: Vol. 187 (2017)
  • Yield, water and nitrogen use efficiencies of sprinkler irrigated wheat
           grown under different irrigation and nitrogen levels in an arid region
    • Authors: Vijay Singh Rathore; Narayan Singh Nathawat; Seema Bhardwaj; Renjith Puthiyedathu Sasidharan; Bhagirath Mal Yadav; Mahesh Kumar; Priyabrata Santra; Narendra Dev Yadava; Om Parkash Yadav
      Pages: 232 - 245
      Abstract: Publication date: June 2017
      Source:Agricultural Water Management, Volume 187
      Author(s): Vijay Singh Rathore, Narayan Singh Nathawat, Seema Bhardwaj, Renjith Puthiyedathu Sasidharan, Bhagirath Mal Yadav, Mahesh Kumar, Priyabrata Santra, Narendra Dev Yadava, Om Parkash Yadav
      A major challenge in crop production is to achieve the goal of increasing both yield and resource use efficiency. Irrigation water and nitrogen (N) are scarce and expensive resources constraining wheat production in arid regions. There is limited information on how irrigation and N supply can be simultaneously manipulated to achieve higher yield, water productivity (WP), and nitrogen use efficiency (NUE) of wheat in arid regions. A two-year field experiment was conducted to investigate the effects of irrigation and N rates on yield, WP and NUE of wheat in a hot, arid environment at Bikaner, India. The experimental treatments comprised of six irrigation [100% (ETm; full evapotranspiration), 90% (ETd1), 80% (ETd2), 70% (ETd3), 60% (ETd4), and 50% (ETd5) of ETc (crop evapotranspiration)] levels, and four N [0 (N0), 40 (N40), 80 (N80), and 120 (N120)kgha−1] rates. Moderate deficit irrigation (ETd2) had greatest WP and caused a 17% reduction in water consumption with only a 5% reduction in yield compared to full irrigation (ETm). The N application improved yield and WP. The NUE declined with a reduction in water application and an increase in N rates. The yield and WP response to N rates modified with irrigation levels.The significant increase in grain yield was recorded with N120 at ETm and ETd1, with N80 at ETd2 and ETd3, and with N40 at ETd4 and ETd5 irrigation levels. The significant increase in WP was recorded with N80 at ETm, ETd1, ETd2 and ETd3, and with N40 at ETd4 and ETd5 irrigation levels. The results suggested that moderate deficit irrigation (ETd2) along with 120kgNha−1 could ensure satisfactory grain yield and WP of wheat in arid regions. The study also indicated that the adoption of an appropriate deficit irrigation and N rate combination can be an effective means to reduce non-beneficial water consumption, achieve higher yield, and improve WP and NUE for wheat in an arid environment.

      PubDate: 2017-04-09T13:45:44Z
      DOI: 10.1016/j.agwat.2017.03.031
      Issue No: Vol. 187 (2017)
  • Effects of water table management on least limiting water range and potato
           root growth
    • Authors: Camila Jorge Bernabé Ferreira; Lincoln Zotarelli; Cássio Antonio Tormena; Libby R. Rens; Diane L. Rowland
      Pages: 1 - 11
      Abstract: Publication date: 31 May 2017
      Source:Agricultural Water Management, Volume 186
      Author(s): Camila Jorge Bernabé Ferreira, Lincoln Zotarelli, Cássio Antonio Tormena, Libby R. Rens, Diane L. Rowland
      Soil physical quality indicator, Least Limiting Water Range (LLWR) is the range of soil water content, where water, oxygen and mechanical resistance are not limiting factors to root growth. The objective of this study was to evaluate LLWR, soil water availability, potato root growth and tuber yield under different water table management levels. Water table level was managed targeting 0.36 and 0.76m below the soil surface, denoted as high (HI) and low (LO) level, respectively. Undisturbed soil core samples were obtained in the 0–0.15, 0.15–0.30 and 0.30–0.45m soil layers to assess the LLWR. Root parameters were assessed using mini-rhizotrons installed into the soil along the potato row. Overall, LLWR decreased in depth due to a decrease in soil organic matter and an increase soil bulk density. The LO resulted in a narrower range for LLWR than HI. In the 0–0.15m soil layer, the soil water content in the HI treatment fell inside the LLWR limits with high frequency during the growing season, but both water table levels resulted in similar root growth. In contrast, in the 0.15–0.30 and 0.30–0.45m soil layers, soil water content fell inside LLWR more frequently in the LO than HI treatment. The LO management increased potato root length and surface area in the 0.15–0.30m soil layer compared to HI; while in the 0.30–0.45m soil layer, roots were not present in the HI likely due to the soil water content that was above LLWR. Optimal potato root growth was observed when the soil water content fell within the LLWR range at the highest frequency during the season. Despite impacts on the root system, similar tuber yields were achieved between LO and HI treatments. Nevertheless, the treatment HI used three times more water to supply the crop water requirement than LO.

      PubDate: 2017-03-06T13:15:43Z
      DOI: 10.1016/j.agwat.2017.02.020
      Issue No: Vol. 186 (2017)
  • Fallow management increases soil water and nitrogen storage
    • Authors: Ketema Tilahun Zeleke
      Pages: 12 - 20
      Abstract: Publication date: 31 May 2017
      Source:Agricultural Water Management, Volume 186
      Author(s): Ketema Tilahun Zeleke
      In regions where rainfall during the cropping season is low and variable, such as most parts of Australia, stored soil moisture determines the yield and sowing time of the following crop. A long-season fallow experiment was conducted in south-eastern Australia, and a biophysical simulation model, APSIM, was evaluated and applied. Stubble cover did not significantly affect fallow soil water storage; once the soil profile was filled during the winter fallow, the presence or absence of stubble cover during the summer fallow made little difference. However, weed growth during the summer period significantly affected the soil water storage. By the time of winter crop sowing, the plant available water (PAW) was depleted by 11% (18mm) in weed free – stubble covered treatment, 14% (23mm) in weed free – stubble free treatments, 34% (52mm) in the weedy – stubble covered treatment, and 42% (64mm) in weedy – stubble free treatment. The weedy (39kgha−1) and weed free (98kgha−1) treatments differed significantly in the amount of soil mineral nitrogen at the end of the fallow period. APSIM was able to simulate the change in soil water storage under the weedy treatment accurately (R2 =0.93, NRMSE=4%). Long term simulation showed that there was an 88% probability of accumulating 140mm PAW by the time of sowing, compared with only 13% probability when weeds were present. If the summer fallow period was not properly managed, the water stored during the winter season could be lost to weeds. While soil water and nitrogen storage may vary with soil type, rainfall amount, rainfall distribution, and weed pressure, fallow weeds must be controlled to ensure accumulation of fallow soil water and nitrogen for a subsequent crop.

      PubDate: 2017-03-06T13:15:43Z
      DOI: 10.1016/j.agwat.2017.02.011
      Issue No: Vol. 186 (2017)
  • Effects of pre-sowing irrigation and straw mulching on the grain yield and
           water use efficiency of summer maize in the North China Plain
    • Authors: Zhenxing Yan; Chao Gao; Yujie Ren; Rui Zong; Yuzhao Ma; Quanqi Li
      Pages: 21 - 28
      Abstract: Publication date: 31 May 2017
      Source:Agricultural Water Management, Volume 186
      Author(s): Zhenxing Yan, Chao Gao, Yujie Ren, Rui Zong, Yuzhao Ma, Quanqi Li
      To develop water-saving agriculture in the North China plain, we conducted field experiments using three pre-sowing irrigation applications (30, 70, and 110mm) on summer maize, with and without straw mulching, during the 2014 and 2015 growing seasons. We studied the effects of pre-sowing irrigation and straw mulching on soil moisture before sowing (SMBS) consumption, evapotranspiration (ET), grain yield, and water use efficiency (WUE). The results indicated that straw mulching and increased pre-sowing irrigation significantly improved grain yield. Increasing amounts of pre-sowing irrigation increased ET, whereas straw mulching had no significant effect on ET. Conversely, while pre-sowing irrigation showed no linear correlation with WUE, straw mulching increased it significantly. The combination of straw mulching and the 70-mm pre-sowing irrigation treatment (70M) improved grain yield at a significantly higher rate than with the combination of 110-mm and the non-straw mulching treatment (110N); moreover, significantly more deep soil water was absorbed with 70M than with the other pre-sowing irrigation treatments. These results indicate that the combination of straw mulching and 70-mm pre-sowing irrigation is the ideal water-saving agricultural technique for growing summer maize in the North China Plain.

      PubDate: 2017-03-06T13:15:43Z
      DOI: 10.1016/j.agwat.2017.02.017
      Issue No: Vol. 186 (2017)
  • Transaction costs associated with agricultural water trading in the Heihe
           River Basin, Northwest China
    • Authors: Xiaohong Deng; Zhongmin Xu; Xiaoyu Song; Jian Zhou
      Pages: 29 - 39
      Abstract: Publication date: 31 May 2017
      Source:Agricultural Water Management, Volume 186
      Author(s): Xiaohong Deng, Zhongmin Xu, Xiaoyu Song, Jian Zhou
      Trading in water via a market has become an effective way to deal with water resource scarcity. Transactions costs (TCs) are known to prevent markets from operating efficiently or from forming altogether. Therefore, evaluation of the level of transactions costs is an important precursor to establish an efficient water market. We analyze one water transaction scenario in the context of government regulation in Zhangye City in the middle reach of the Heihe River Basin (HRB) in China: water rights-trading between irrigation areas in agricultural use, which is one of the most urgent scenarios and maximizes the likelihood of a transaction in future. The results show that without calculating the transfer costs and the third-party effect costs, TCs per unit water range between 0.004 and 0.247yuan/m3 based on the set of transaction scales and cost limits in the middle reach of the HRB. Under the most realistic transaction case i.e., only one purchaser in the Luotuocheng irrigation district in Gaotai County and several sellers located in Ganzhou County, the lowest TCs per water are associated with trading between the Daman and Luotuocheng irrigation districts at a maximum trading scale of the water amount and with minimum costs. The highest TCs result from obtaining water from the Xidong intake in the Xijun irrigation district. In addition, given the highest permitted trading price of the local government-set standards (three times the agricultural water price, approximately 0.3yuan/m3), the transaction costs would range from 1% to 93% of the water trade price, and acceptable lower transaction costs can be obtained through appropriate operations and trading scales.

      PubDate: 2017-03-06T13:15:43Z
      DOI: 10.1016/j.agwat.2017.02.021
      Issue No: Vol. 186 (2017)
  • Soil vs. groundwater: The quality dilemma. Managing nitrogen leaching and
           salinity control under irrigated agriculture in Mediterranean conditions
    • Authors: Angela Libutti; Massimo Monteleone
      Pages: 40 - 50
      Abstract: Publication date: 31 May 2017
      Source:Agricultural Water Management, Volume 186
      Author(s): Angela Libutti, Massimo Monteleone
      A 3-year field trial was carried out in southern Italy on an agricultural farm close to the seacoast of Manfredonia Gulf (Apulia Region) where crop irrigation with saline water is standard practice. Seawater intrusion into the groundwater, and the consequent soil salinization represent a serious environmental threat. Each year, two crop cycles were applied, in spring-summer and autumn-winter seasons, respectively. The crop pairing over the three years was tomato and spinach; zucchini and broccoli; pepper and wheat. Cultivation was performed in a field-unit characterised by three adjacent plots. At the centre of each plot, a hydraulically insulated drainage basin was dug (0.70m depth) to collect the draining water. The crops were irrigated with saline water and leaching treatments were applied with saline or fresh water whenever soil salinity reached a predetermined electrical conductivity threshold. Since soil salinity control might increase nitrate leaching, operational criteria should optimize the trade-off between the application of higher water volumes to reduce soil salinity and lower water volumes to protect groundwater quality from nitrate leaching. The amount of nitrogen leached from the soil root-zone was considerable (on average, 156kgNha−1 year−1) and higher in autumn-winter than spring-summer (72 vs. 28% of the average annual value). In autumn-winter season, nitrogen losses were mainly due to plentiful nitrogen fertilisation and high rainfall. In spring–summer, extra irrigations promoted salt leaching together with nitrogen losses. To manage both irrigation and nitrogen fertilisation a “decoupling” strategy is recommended. This strategy suggests applying leaching preferably at the end of the spring-summer growing season, soon after crop harvesting or at the beginning of the autumn-winter season, before second crop cycle starting. In autumn-winter season, proper nitrogen supplies and timely top-dressing applications, still allow salts to be discharged by rainfalls but prevent nitrogen losses, thus preserving groundwater quality.

      PubDate: 2017-03-06T13:15:43Z
      DOI: 10.1016/j.agwat.2017.02.019
      Issue No: Vol. 186 (2017)
  • Quantifying the effects of conservation practice implementation on
           predicted runoff and chemical losses under climate change
    • Authors: Carlington W. Wallace; Dennis C. Flanagan; Bernard A. Engel
      Pages: 51 - 65
      Abstract: Publication date: 31 May 2017
      Source:Agricultural Water Management, Volume 186
      Author(s): Carlington W. Wallace, Dennis C. Flanagan, Bernard A. Engel
      The Soil and Water Assessment Tool with downscaled weather data generated using the MarkSim weather file generator was used to evaluate the impact of long-term conservation practice implementation on runoff, sediment, atrazine, nitrogen (N) and phosphorus (P) losses in an agricultural watershed located in northeastern Indiana. As part of the Conservation Effects Assessment Project, evaluation of these conservation practices is required to provide insight on how their implementation is benefiting the environment. The results indicate that individual conservation practices were effective in reducing a particular pollutant load, but combined practices were more effective in reducing multiple pollutant loads simultaneously. Of the individual best management practices (BMPs) assessed, no-till was the most effective in reducing multiple pollutant loads (reduced surface runoff by an average of 25%, sediment by 46%, atrazine by 46%, total N by 9%, soluble P by 16%, and total P by 29%). When BMPs were combined, pollutant load reductions were increased significantly (at α=0.05) for all pollutants, both under baseline and future climate scenarios. The reductions in runoff and pollutant loads for each decade of future climate ranged from 15 to 25% for surface runoff, 32–68% for sediment loss, 37–60% for atrazine loss, 5–13% for soluble N loss, 12–35% for total N loss, 9–41% for soluble P loss, and 33–60% for total P loss.

      PubDate: 2017-03-06T13:15:43Z
      DOI: 10.1016/j.agwat.2017.02.014
      Issue No: Vol. 186 (2017)
  • Productivity and production components of safflower genotypes affected by
           irrigation at phenological stages
    • Authors: Reginaldo Ferreira Santos; Doglas Bassegio; Marcelo de Almeida Silva
      Pages: 66 - 74
      Abstract: Publication date: 31 May 2017
      Source:Agricultural Water Management, Volume 186
      Author(s): Reginaldo Ferreira Santos, Doglas Bassegio, Marcelo de Almeida Silva
      Drought and the scarce resource of water for irrigation can limit agricultural production under tropical conditions. The objective of this study was to investigate the growth and yield response of safflower genotypes to water deficit in the soil profile during vegetative, flowering and yield formation stages, both in clayey and sandy soils. The experiments were carried out in Engenheiro Coelho, SP, Brazil, in autumn-winter 2014. The experimental design was a randomized block in a factorial arrangement, consisting of the genotypes IMA-2232, IMA-4409, IMA-2109 and IAPAR, and irrigation schemes water deficit (WD), irrigation at the vegetative stage (V), irrigation at the grain formation stage (G), irrigation at the vegetative and flowering (VF) stages, irrigation at the vegetative and grain formation (VG) stages, irrigation at the flowering and grain formation (FG) stages and irrigation at the vegetative, flowering and grain formation (VFG) stages (control). The growth of safflower genotypes, yield components and grain and oil yield were weaken by gradual water restriction at the stages, especially at the vegetative stage in both soils. The water regime with irrigation at the flowering stage and grain formation (FG) only did not reduce the oil content in the genotypes in clayey soil. The IAPAR genotype produced more grains (2.7Mgha−1), while the IMA-4409 genotype had higher oil content (42.8%) but they both had similar oil yield (0.75 and 0.79Mgha−1, respectively) on the clayey soil with irrigation throughout the cycle (VFG). Oil yield in the sandy soil treatment was similar to that of clayey soil (0.72Mgha−1) in VFG, in particular for the IMA-4409 genotype. The IAPAR and IMA-4409 genotypes were generally less sensitive to interruption of water supply at the growth stages. In general, the higher total water storage in soil profile of clayey soil, compared to sandy soil, did not benefit the safflower crop. On an average, irrigation only at vegetative and flowering stage (VG) stages can save 15% of water but with a corresponding 50% reduction in yield, both in clayey soil and sandy soil. The irrigation during the VFG stages might be practiced to attain the highest yield of safflower genotypes.

      PubDate: 2017-03-11T13:37:10Z
      DOI: 10.1016/j.agwat.2017.02.013
      Issue No: Vol. 186 (2017)
  • Impacts of irrigation scheduling on pore water nitrate and phosphate in
           coastal plain region of the United States
    • Authors: G.C. Sigua; K.C. Stone; P.J. Bauer; A.A. Szogi; P.D. Shumaker
      Pages: 75 - 85
      Abstract: Publication date: 31 May 2017
      Source:Agricultural Water Management, Volume 186
      Author(s): G.C. Sigua, K.C. Stone, P.J. Bauer, A.A. Szogi, P.D. Shumaker
      Agriculture is one of the largest sources of nutrient contamination, mainly inorganic nitrogen (N) fertilization of intensive crops, such as maize (Zea mays L). Proper irrigation management can reduce nutrient leaching while maintaining crop yield, which is critical in enhancing the sustainability of agricultural crops on soils with low water and nutrient holding capacities. A three-year (2012–2014) field study was conducted to evaluate the effects of three irrigation scheduling methods (ISM): Irrigator Pro (IPRO); Normalized Difference Vegetative Index (NDVI); and Soil Water Potentials (SWP) and two rates of N applications (NM) on pore water nitrate and phosphate in four soil types (ST) with maize production in Coastal Plain Region, USA. Soil pore water nitrate varied significantly with ISM and NM, but not with ST. The IPRO method had the lowest soil water pore nitrate followed by SWP and NDVI. The low N application rate resulted in lower nitrate concentration (13.4mgL−1) than the high N rate (17.0mgL−1). Soil water pore phosphate was not affected by ISM, NM and ST. The use of IPRO reduced the concentration of pore water nitrate by about 39% and 33% when compared with NDVI and SWP, respectively. Using IPRO method resulted in lower soil water pore nitrate and phosphate concentrations, results indicate scheduling method may be a way to reduce nutrient losses. Results of our study suggest that irrigation management decision may affect nitrogen and phosphorus availability for achieving optimum yield of maize while potentially minimizing nutrient losses via leaching.

      PubDate: 2017-03-11T13:37:10Z
      DOI: 10.1016/j.agwat.2017.02.016
      Issue No: Vol. 186 (2017)
  • An interval multistage water allocation model for crop different growth
           stages under inputs uncertainty
    • Authors: Shu Chen; Dongguo Shao; Wenquan Gu; Baoli Xu; Haoxin Li; Longzhang Fang
      Pages: 86 - 97
      Abstract: Publication date: 31 May 2017
      Source:Agricultural Water Management, Volume 186
      Author(s): Shu Chen, Dongguo Shao, Wenquan Gu, Baoli Xu, Haoxin Li, Longzhang Fang
      Due to different responses of crop growth stages to the water deficit, it is necessary to optimize water allocation between different growth stages to obtain the maximum food production in reservoir irrigation systems which are widely distributed throughout Southern China and India. In order to address the inputs uncertainties and dynamics existing in the above agricultural water management, an interval multistage water allocation model is developed. By incorporating multistage stochastic programming and interval parameter programming, the developed model can deal with uncertain inputs both expressed as interval parameters and probability distributions, and realize a dynamic irrigation among different growth stages from a reservoir. In the model, water requirement targets are first treated as first-stage decision variables to tackle the unique problem of agricultural water management. Additionally, given that net benefit and penalty of each growth stage are key parameters due to their determinative roles for allocation between different growth stages, a crop water production function is introduced into the calculation to make them factually reflect the competition among different growth stages. The model is then applied to the Yangshudang Irrigation District to plan rice irrigation and demonstrate its applicability. Rainfall has been divided into five levels with probability distributions in each growth stage and parameters have been characterized as interval numbers to show system uncertainty. Five scenarios that represent different initial active storage levels of the reservoir are set to acquire more detailed results. Through the parameter estimation, net benefits are [1.08, 1.29], [5.04, 6.01], [11.79, 14.08] and [1.61, 1.92] RMB/m3, and penalties are [2.39, 2.48], [11.13, 11.54], [26.05, 27.01] and [3.55, 3.68] RMB/m3 for tillering stage, booting stage, heading stage and milky stage respectively. Through the model simulation, water requirement targets in booting stage and heading stage under all scenarios are set at their upper bound, while this figure in tillering stage reaches its upper bound only when initial active storage is under high or very high level. The results show that irrigation water can be optimally allocated between different growth stages of a single crop in a single reservoir system under inputs uncertainty. Although there is a limitation to regard rainfall as to be uniform in the whole area, the solutions of water requirement targets under different scenarios, as well as water allocation patterns among different growth stages, are valuable for optimizing irrigation water use in meso- and micro-scale agricultural system under inputs uncertainty.

      PubDate: 2017-03-18T09:46:05Z
      DOI: 10.1016/j.agwat.2017.03.001
      Issue No: Vol. 186 (2017)
  • Sour orange rootstock increases water productivity in deficit irrigated
           ‘Verna’ lemon trees compared with Citrus macrophylla
    • Authors: J.M. Robles; P. Botía; J.G. Pérez-Pérez
      Pages: 98 - 107
      Abstract: Publication date: 31 May 2017
      Source:Agricultural Water Management, Volume 186
      Author(s): J.M. Robles, P. Botía, J.G. Pérez-Pérez
      The response to a regulated deficit irrigation (RDI) strategy was evaluated in trees of ‘Verna’ lemon grafted on two rootstocks with different vigour. The experiment was carried out during three consecutive years in the IMIDA experimental orchard located in Torre Pacheco (Murcia, Spain), using 8-year-old trees of ‘Verna 51’ lemon grafted on Citrus macrophylla Wester (CM) and sour orange (Citrus aurantium L.) (SO). The tree spacing was 4×5m and irrigation was applied through one drip line per tree row, with four self-compensated drippers (4Lh−1) per tree. Two irrigation treatments were applied: Control (100% ET c ) and RDI. The RDI trees were fully irrigated (100% ET c ) along the season except in two fruit growth periods, phase I (cell division) and phase III (ripening and harvest), the irrigation applied being 25% ET c . The main results show that fully-irrigated trees on CM had better plant water status and greater efficiency of water use, which led to higher pruning weight and yield than on SO. With respect to fruit quality, CM fruits had higher juice content, while the fruits from SO trees had higher total soluble solids (TSS). However, under RDI the responses of the rootstocks differed. The water deficit imposed during the stress periods affected much more the plant water status of trees on SO than that of trees on CM, but the pruning weight decreased much more in CM trees than in SO trees. The RDI also affected the accumulated yield much more in CM trees (which suffered a 28% decrease) than in SO trees, which maintained values similar to those of the control. Fruit quality was affected by the RDI treatment similarly in the two rootstocks, with both the titratable acidity and TSS increasing. Thus, based on these results, we recommend the use of the CM rootstock for ‘Verna’ lemon trees grown in regions where the available water resources are not limiting, due to its higher vigour. However, we recommend the use of the SO rootstock when the water availability is not assured, due to its higher water stress tolerance.

      PubDate: 2017-03-18T09:46:05Z
      DOI: 10.1016/j.agwat.2017.03.002
      Issue No: Vol. 186 (2017)
  • Towards shifting planting date as an adaptation practice for rainfed wheat
           response to climate change
    • Authors: Milad Nouri; Mehdi Homaee; Mohammad Bannayan; Gerrit Hoogenboom
      Pages: 108 - 119
      Abstract: Publication date: 31 May 2017
      Source:Agricultural Water Management, Volume 186
      Author(s): Milad Nouri, Mehdi Homaee, Mohammad Bannayan, Gerrit Hoogenboom
      Maintaining rainfed crop production particularly in water-limited environments is of great importance for agricultural water management under climate change (CC). In such conditions, there is a real demand for finding some practical adaptation scenarios to sustain optimal crop production. This study aimed to investigate the impacts of CC on rainfed wheat yield, transpiration to total evapotranspiration ratio (T/ET) and maximum leaf area index (LAIm) in some semi-arid areas in Iran over 2071–2100 under the current and shifted planting date scenarios. Consequently, the outputs of five climate models under RCP-4.5 and RCP-8.5 emission scenarios downscaled by MarkSimGCM were used to run the CSM-CERES-Wheat v4.6 model. Results revealed that crop yield, T/ET and LAIm will decrease chiefly due to October–November–December (OND) and January–February–March (JFM) precipitation deficit under current sowing date at the most studied sites. Unlike early planting, postponing sowing date from the current to the best date as an adaptive alternative will increase the received precipitation during two early growth phases i.e. germination to terminal spikelet initiation (G-TS) and terminal spikelet to end of leaf growth and beginning of ear growth (TS-ELG). However, a considerable change in the precipitation of entire growing season and grain filling (GF) stage due to delay in sowing date was not projected. Enhanced G-TS rainfall will ensure crop emergence and establishment. Moreover, precipitation increase at TS-ELG phase in which the highest decrease of precipitation was predicted, would enhance LAIm and T/ET. This can be attributed to the fact that the vapor flux in the soil–plant–atmosphere system may shift in favor of transpiration loss through delaying planting date. Therefore, by better matching crop development with changed rainfall distribution, postponing sowing date can partially compensate the deleterious impacts of CC-induced drought on rainfed wheat yield in the west and northwest Iran during 2071–2100.

      PubDate: 2017-03-18T09:46:05Z
      DOI: 10.1016/j.agwat.2017.03.004
      Issue No: Vol. 186 (2017)
  • Improved volume balance using upstream flow depth for advance time
    • Authors: Reza Lalehzari; Saeed Boroomand Nasab
      Pages: 120 - 126
      Abstract: Publication date: 31 May 2017
      Source:Agricultural Water Management, Volume 186
      Author(s): Reza Lalehzari, Saeed Boroomand Nasab
      Modification of classical volume balance models is one of the effective strategies to improving design of surface irrigation and optimal usage of water resources in agricultural section. In this paper, a modified volume balance model is developed to predict the advance curve in surface irrigation based on the variable actual depth at the upstream end of furrow. The simulations of the suggested structure are generated through a combination of different values of the furrow irrigation variables (inflow discharge, length of furrow, and infiltration parameters), to compare between different models and measured data. The results show that the modified volume balance is more accurate than previous equations by model efficiency of 0.94, 0.98, and 0.97 for furrow length of 60, 80, and 100m, respectively. Sensitivity analysis is made by changing only one input parameter including discharge, field slope, roughness coefficient and infiltration parameters at a time while keeping all others fixed. Furthermore, the inflow rate can have a considerable impact on the model estimations. Nevertheless, the developed model is more sensitive to decreasing inflow discharge amount than to increasing it.

      PubDate: 2017-03-18T09:46:05Z
      DOI: 10.1016/j.agwat.2017.03.005
      Issue No: Vol. 186 (2017)
  • Intensifying a semi-arid dryland crop rotation by replacing fallow with
    • Authors: David C. Nielsen; Merle F. Vigil
      Pages: 127 - 138
      Abstract: Publication date: 31 May 2017
      Source:Agricultural Water Management, Volume 186
      Author(s): David C. Nielsen, Merle F. Vigil
      Increasing dryland cropping system intensity in the semi-arid central Great Plains by reducing frequency of fallow can add diversity to cropping systems and decrease erosion potential. However elimination of the periodic fallow phase has been shown to reduce yields of subsequent crops in this region. The objective of this experiment was to determine how productivity of a 4-yr WCMF rotation [wheat (W, Triticum aestivum L.); corn (C, Zea mays L.); proso millet (M, Panicum miliaceum L.); fallow (F)] was affected when the fallow phase was replaced with pea (P, Pisum sativum L.). The effect of this intensification of the WCMF rotation on the available soil water content at planting, the water use, and the yield of each crop, and on total system productivity and net income was quantified by analyzing data over a 20-yr period from a long-term crop rotation experiment at Akron, CO. Large year-to-year variations were found for available soil water at planting, water use, and yield for all four crops. Pea water use resulted in significant reductions in available soil water at planting, water use, and yield for wheat and corn, but had little effect on those quantities in the millet crop. Total production on a seed mass basis was not different between the WCMF and WCMP rotations, but system net income for the WCMP rotation was 32% lower than for WCMF. Intensification of the WCMF rotation by replacing the fallow phase with pea production could be recommended as an alternative production method if pea seed costs and nitrogen fertilizer applied to the subsequent wheat crop can be reduced.

      PubDate: 2017-03-18T09:46:05Z
      DOI: 10.1016/j.agwat.2017.03.003
      Issue No: Vol. 186 (2017)
  • Effects of two slow-release nitrogen fertilizers and irrigation on yield,
           quality, and water-fertilizer productivity of greenhouse tomato
    • Authors: Yanmei Li; Yanxin Sun; Shangqiang Liao; Guoyuan Zou; Tongke Zhao; Yanhua Chen; Jungang Yang; Lin Zhang
      Pages: 139 - 146
      Abstract: Publication date: 31 May 2017
      Source:Agricultural Water Management, Volume 186
      Author(s): Yanmei Li, Yanxin Sun, Shangqiang Liao, Guoyuan Zou, Tongke Zhao, Yanhua Chen, Jungang Yang, Lin Zhang
      Technical research on efficient water and nitrogen use is crucial for sustainable agricultural development. A field experiment was conducted to investigate the combined effects of two slow-release nitrogen fertilizers (polymer-coated urea (PU) and carbon-based urea (CU)) and two different irrigation water levels (conventional irrigation, CI; 90% of conventional irrigation, RI) on tomato yield, quality, and water-fertilizer productivity. Tomato yield and irrigation water productivity improved when nitrogen fertilizer was applied. Compared with U application, CU application increased tomato fruit diameter, volume, single-fruit weight, yield, and water-fertilizer productivity, therefore increasing yield by 4600kgha−1 and net income from tomato cultivation by 6313yuanha−1. Treatment with the two slow-release nitrogen fertilizers increased soluble sugar and lycopene contents and reduced nitrate content in fruits. Compared with U treatment, PU and CU treatments decreased total nitrate nitrogen residue in the 0–100cm soil layer. Compared with CI, RI significantly reduced tomato yield and net incomes under PU treatment, whereas RI did not significantly reduce tomato yield and net income under CU treatment. RI increased fruit Vc (vitamin C) and lycopene contents. Results of the study indicated that polymer-coated slow-release fertilizers may have great potential for widespread use because they improved tomato fruit quality while reducing the environmental risks caused by soil nitrogen. In addition, carbon-based, slow-release nitrogen fertilizers promise to improve fruit quality, yield, water-fertilizer productivity, and benefits associated with tomato cultivation. These fertilizers also reduce environmental risks caused by soil nitrogen and help reduce irrigation water consumption while sustaining normal tomato growth and fruit yield, making their promotion extremely beneficial.

      PubDate: 2017-03-25T13:19:03Z
      DOI: 10.1016/j.agwat.2017.02.006
      Issue No: Vol. 186 (2017)
  • Long-term field response of pistachio to irrigation water salinity
    • Authors: Houda Mehdi-Tounsi; Azza Chelli-Chaabouni; Dalenda Mahjoub-Boujnah; Makki Boukhris
      Pages: 1 - 12
      Abstract: Publication date: 1 May 2017
      Source:Agricultural Water Management, Volume 185
      Author(s): Houda Mehdi-Tounsi, Azza Chelli-Chaabouni, Dalenda Mahjoub-Boujnah, Makki Boukhris
      A three years field study was conducted to assess the effects of moderate and high saline irrigation water on the behavior of 5-year-old female trees of pistachio. Mateur cultivar was grafted on Pistacia vera L. and Pistacia atlantica Desf. rootstocks. Different water irrigation qualities were used: (i) tap water (ECw: 1.95dSm−1); (ii) moderately saline water (ECw: 5dSm−1); and (iii) highly saline water (ECw: 12dSm−1). Rootstock and scion growth were measured. Fruit yield was monitored during the three years of salt treatment and the following year after salt stress was relieved. Leaf mineral content and electrolyte leakage were determined monthly during growing seasons. Results showed that tree growth was not affected by moderate salinity after the first season of experiments but the response changed at higher salinity and when salt treatment duration increased. Salinity of irrigation water did not affect average fruit yield per tree but when saline water irrigation was stopped, yield of trees previously irrigated with highly saline water increased significantly on P. atlantica rootstock in comparison with control. Sodium and chlorides ions content in leaves accumulated proportionally to salinity level and duration. Nitrogen (N), phosphorus (P), potassium (K) and calcium (Ca) as well as K/Na and Ca/Na ratios decreased with increasing salt concentration in the irrigation water. This reduction was more significant in the second and third years of the study. Water management practice was proposed to take advantage from the stimulating effects of mild/short term salinity on growth and production of pistachio Mateur cultivar.

      PubDate: 2017-02-14T01:44:27Z
      DOI: 10.1016/j.agwat.2017.02.003
      Issue No: Vol. 185 (2017)
  • Soil water content monitoring for irrigation management: A geostatistical
    • Authors: Burdette Barker; Trenton Franz Derek Heeren Christopher M.U. Neale Joe
      Abstract: Publication date: 1 July 2017
      Source:Agricultural Water Management, Volume 188
      Author(s): J. Burdette Barker, Trenton E. Franz, Derek M. Heeren, Christopher M.U. Neale, Joe D. Luck
      With the increasing attention to site-specific or variable rate irrigation management, it is helpful to reconsider the quantity and placement of soil water monitoring locations in this context. Volumetric soil water content (θv) was monitored using a neutron probe (NP) at 72 locations in a center pivot irrigated field in eastern Nebraska. Variance reduction and temporal stability analyses were performed on θv from shallow (∼top 46cm) and full profile (∼122cm) readings for four monitoring cycles in the 2015 growing season and 2016 preseason. Eleven additional cycles were included for a subset of the data for the temporal stability analysis. The spatial correlation scale for θv was found to be less than the closest spacing of monitoring locations in the study (i.e. <37m). For this field site, approximately three neutron probe monitoring locations were required to determine mean soil water depletion (±2cm) for the field or for a management zone. Little economy would be gained in variance reduction for areal mean θv from using a stratified network for management areas of reasonable size in a center pivot irrigated field. Temporally stable monitoring locations were identified. However, relatively low-cost spatial predictor variables, including elevation, deviation from mean elevation, apparent electrical conductivity, and mean relative difference of interpolated cosmic ray neutron probe surveys, were not consistent predictors of NP mean relative difference. The small range of variability of θv within the study field is thought to be a contributing factor. It is possible that for fields with similar variability, or for site-specific irrigation where zones have been selected to reduce within-zone variance, that sensor quantity is more important than sensor placement in quantifying the areal mean θv for irrigation management.

      PubDate: 2017-04-16T03:15:41Z
  • Inside Front Cover (with Editorial Board)
    • Abstract: Publication date: 31 May 2017
      Source:Agricultural Water Management, Volume 186

      PubDate: 2017-04-09T13:45:44Z
  • Inside Front Cover (with Editorial Board)
    • Abstract: Publication date: 1 May 2017
      Source:Agricultural Water Management, Volume 185

      PubDate: 2017-03-25T13:19:03Z
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