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ARS Home » Research » Publications at this Location » Publication #349615
Title: Yield and water productivity of winter wheat under various irrigation capacities

Author
item ARAYA, ALEMIE - Kansas State University
item VARAPRASAD, P - Kansas State University
item Gowda, Prasanna
item KISEKKA, ISAYA - University Of California, Davis
item FOSTER, ANSERD - Kansas State University

Submitted to: Journal of the American Water Resources Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/4/2018
Publication Date: 2/1/2019
Citation: Araya, A., Varaprasad, P.V., Gowda, P.H., Kisekka, I., Foster, A. 2019. Yield and water productivity of winter wheat under various irrigation capacities. Journal of the American Water Resources Association. 55(1):24-37. https://doi.org/10.1111/1752-1688.12721.
DOI: https://doi.org/10.1111/1752-1688.12721

Interpretive Summary: Ogallala aquifer is the major source of groundwater for irrigated winter wheat. However, groundwater levels in the Ogallala aquifer have declined due to excessive pumping combined with relatively low recharge rates. This has greatly reduced pumping capacities of the wells in the region. Identifying suitable crop for lower pumping capacities is crucial for sustainable crop production in the region. Winter wheat is an important food crop grown in southwest Kansas under both irrigation and dryland management practices. In this study, a crop growth simulation was used to evaluate feasibility of growing winter wheat under different irrigation capacities using historic climate data for western Kansas. Simulation results indicated that crop yield increased at higher rates with increase in irrigation up to 2.5 mm/day (total seasonal irrigation of 97 mm). However, the rate of increase gradually reduced with additional irrigation. This indicates that winter wheat in southwest Kansas is responsive to deficit irrigation strategies and it is possible to reduce groundwater use by 50% incurring only 10 - 20% yield loss.

Technical Abstract: Winter wheat is an important food crop grown in western Kansas under both irrigation and dryland management practices. Ogallala aquifer is the major source of groundwater for irrigated winter wheat. However, groundwater levels in the Ogallala aquifer have declined due to excessive pumping combined with relatively low recharge rates. This has greatly reduced pumping capacities of the wells in the region. Identifying suitable crop for lower pumping capacities is crucial for sustainable crop production in the region. The Agricultural Production Systems sIMulator (APSIM) validated in prior study for winter wheat was used to simulate the yield, biomass, transpiration, evapotranspiration under four irrigation capacities (IC) [0 mm/day (dryland), 1.7 mm/day (25 mm in 15 days), 2.5 mm/day (25 mm in 10 days), and 5 mm/day (25 mm in 5 days)] and two nitrogen rates (N1, 94 kg N/ha; N2, 160 kg N/ha)] to (1) understand the response and performance of winter wheat to irrigation under different ICs based on yield, biomass, transpiration efficiency (TE), crop water productivity (WP) and irrigation water productivity (IWP) for winter wheat; and (2) quantify the relationships between yield and crop transpiration or evapotranspiration under various water allocation strategies to develop crop water production functions. Simulation results showed that winter wheat yield increased at higher rates with increase in irrigation up to 2.5 mm/day. However, the rate of yield increase gradually reduced with additional irrigation. A 5 mm/day strategy required a total of 190 mm irrigation and gave a 10% and 20% yield advantage over 2.5 mm/day strategy with a total irrigation of 97 mm relative to the dryland wheat when treated with N1 and N2, respectively. This indicates that winter wheat in southwest Kansas is responsive to deficit irrigation strategies and it is possible to reduce groundwater use by 50% incurring only 10 - 20% yield loss. In addition, TE of winter wheat under 5, 2.5, 1.7 and 0 mm irrigation per day were 14.7 – 15.5, 15.1 – 16.0, 15.2 – 16.1, and 15.5 – 16.5 mm/day, respectively. The IWP for grain was moderately high (0.98 - 1.6 kg/m3) under IC 1.7 mm/day followed by under IC 2.5 mm/day (0.86 - 1.44 kg/m3). Given that TE and IWPs are high under lower IC and as the aquifer water level is also quickly declining, winter wheat could be suitable crop under lower pumping capacities in the region.