Evaluating the impact of future climate change on irrigated maize production in Kansas

Authors: ARAYA, BERTHE - Kansas State University; KISEKKA, ISAYA - Kansas State University; LIN, XIAOMAO - Kansas State University; VARA PRASAD, P.V.V - Kansas State University; Gowda, Prasanna; RICE, CHARLES - Kansas State University; ANDALES, ALAN - Colorado State University

Submitted to: Grazinglands Research Laboratory Miscellaneous Publication
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/2/2017
Publication Date: 8/5/2017
Citation: Araya, B.A., Kisekka, I., Lin, X., Vara Prasad, P., Gowda, P., Rice, C., Andales, A. 2017. Evaluating the impact of future climate change on irrigated maize production in Kansas. Climate Risk Management. http://dx.doi.org/10.1016/j.crm.2017.08.001.

Interpretive Summary: Climate change may modify precipitation, soil water, runoff, and may reduce crop maturation period and increase yield variability and could reduce areas suitable for the production of many crops. Maize is one of the major commercial crops grown under irrigation in western Kansas. Rainfall covers only a portion of the crop evapotranspiration, and irrigation supplies a significant proportion of crop water needs. The demand for water under future climate may increase because of frequent occurrence of extreme weather events such as severe droughts and thus more water may be required during dry climatic conditions. The fate of maize in western Kansas under changing climate is therefore compounded by over extraction of the groundwater and occurrence of extreme weather events. Therefore, there is a need to understand how irrigated maize production in this region might respond to the combined effects of constrained water supplies and extreme weather events. In this simulation study, we assessed the impact of future climate change on maize (Zea mays L.) yield in western Kansas; and evaluated impacts of climate change on maize irrigation water productivity, transpiration, evapotranspiration and days to maturity. Results showed that maize yield during the mid-21st century will decline relative to the present on average by 18–46%. The yield decline might be caused mainly by shortening of the growing period (9–18% decline in days to maturity), attributed to elevated temperatures. The reduction in transpiration relative to the baseline reached 15% under deficit irrigation whereas the reduction was minimal (1–7%) under full irrigation. Simulated yield increase due to elevated CO2 concentration might be masked by the increased temperatures. Irrigation water productivity of maize under deficit irrigation was slightly higher than that under full irrigation. The difference in irrigation water productivity of maize between the deficit and full irrigation was larger for early compared to normal and late planting. These differences justify that early planting may be suitable under future climate even though the simulated yield with early planting under similar irrigation levels are not significantly different from late planting.

Technical Abstract: The United States southern and central High Plains including western Kansas are experiencing declining ground water supplies from the Ogallala as a result of withdrawals for irrigation exceeding annual recharge, this situation will be exacerbated by future climate change. The purpose of this simulation based study was to 1) assess the impact of future climate change on maize (Zea mays L.) yield in western Kansas; and 2) evaluate and understand the possible impacts of climate change on maize irrigation water productivity, transpiration, evapotranspiration and days to maturity. The Crop Estimation through Resource and Environment Synthesis (CERES-Maize) crop model within the Decision Support System for Agrotechnology Transfer Cropping Systems Model (DSSAT-CSM) was used in combination with multiple Global Climate Models under two Representative Concentration Pathways (RCPs), and two irrigation scenarios [full (450 mm) and deficit (300)] under three planting dates [early (20th April), normal (5th May) and late (15th May)]. Results showed that maize yield during the mid-21st century will decline relative to the present on average by 18–33% under RCP4.5 and 37–46% under RCP8.5. The yield decline might be caused mainly by shortening of the growing period (9–18% decline in days to maturity), attributed to elevated temperatures. The reduction in transpiration relative to the baseline reached 15% for RCP8.5 under deficit irrigation whereas the reduction was minimal (1–7%) under full irrigation. Indicating that significant yield reductions might occur due to combined effects of deficit irrigation and shortening of the maturity period. Yield increase due to elevated CO2 concentration [CO2] might be masked by the increased temperatures. The current study showed large disparity in simulated yield among the various GCMs. Planting date did not substantially improve yield but there was less simulation variability among GCMs with early planting compared to normal and late planting. There was no substantial difference among the planting dates for water productivity, however, there was a slight tendency of improvement in irrigation water productivity for deficit irrigation under early planting compared to normal and late planting. Under all planting dates and RCPs, the irrigation water productivity of maize under deficit irrigation was slightly higher than that under full irrigation. The difference in irrigation water productivity of maize between the deficit and full irrigation was larger for early compared to normal and late planting. These differences justify that early planting may be suitable under future climate compared to late planting even though the simulated yield with early planting under similar RCPs and irrigation levels are not significantly different from late planting.