Simulated Corn Yield Responses to Limited-Water Irrigation Under Varying Soil and Climate Conditions.
Saseendran S.A.1, Lajpat Ahuja1, Liwang Ma1, David Nielsen2, Thomas Trout3, Neil Hansen4, and Allan A. Andales5. (1) Agricultural Systems Research Unit, USDA-ARS-NPA Great Plains Systems Research, 2150 Centre Avenue #D-100, Fort Collins, CO 80526-8116, (2) Central Great Plains Research Station, USDA-ARS, 40335 County Rd. GG, Akron, CO 80720, (3) Water management unit, USDA-ARS, 2150 Centre Ave, Ft. Collins, CO 80526-8119, (4) C-138 Plant Sciences, Colorado State University, Colorado State University, Soil & Crop Sciences (1170), Ft. Collins, CO 80523-1170, (5) Soil and Crop Sciences, Colorado State University, C111 Plant Sciences, 1170 Campus Delivery, Colorado State University, Fort Collins, CO 80523-1170
Water holding capacity of soils is a key factor in successful dryland and irrigated agriculture as it influences the fraction of precipitation and irrigation that is stored in the soil profile that can be subsequently used for crop production. There is a well-known dependence of water holding capacity on soil texture. In a recent study, we calibrated, validated, and applied the CERES-Maize v4.0 model for simulating limited-water irrigation management strategies for corn in a Rago silt loam soil at Akron, Colorado. The results showed that for all different levels of irrigation, optimum production and WUE with minimum N losses were found when 20% of the available irrigation supply was applied during the vegetative stage and 80% during the reproductive stage (split irrigation strategy). We also found that the number of irrigations could be reduced and the water significantly saved if irrigations were initiated at 80% depletion of the plant available soil water (PAW) (later than commonly practiced initiation of irrigation). In this paper, we used simulation modeling to evaluate the above limited irrigation strategies for two other soil types (Nunn clay loam and Julesburg sandy loam) commonly occurring in the area. For both the soils, the water level-production functions, optimum irrigation levels, and WUE responses were similar and best results were found with the 20-80% split irrigation strategy, as for the Rago silt loam soil. However, optimum yield levels were slightly different. For the late initiation of irrigation, optimum yields were achieved when water was applied at 60% depletion of PAW for the Nunn clay loam soil, and at 70% depletion of PAW for the Julesburg sandy loam soil. Reasons for these differences will be discussed.