|ARAYA, ALEMIE - Kansas State University|
|KISEKKA, ISAYA - Kansas State University|
Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/2016
Publication Date: 11/2/2016
Citation: Araya, A., Kisekka, I., Gowda, P. 2016. Evaluation of water-limited cropping systems in a semi-arid climate using DSSAT-CSM. Agricultural Water Management. 150:86-98.
Interpretive Summary: In western Kansas, rainfall is spatially and temporally variable and not adequate to meet crop water needs and thus crops are often grown with irrigation. In this study, a crop growth model was used to assess yield, water productivity, and irrigation water use efficiency of water limited cropping systems in western Kansas. Simulation results indicated that corn under full irrigation might be preferable to deficit irrigation when sufficient water available. Under deficit irrigation, corn in rotation produced higher yields when compared to continuous corn. However, yield and water productivity of continuous wheat was higher than that in a rotation. In addition, wheat grain yield under deficit irrigation was comparable to that under full irrigation.
Technical Abstract: Water is the major factor limiting crop production in western Kansas due to declining groundwater levels in the Ogallala aquifer resulting from withdrawals for irrigation exceeding recharge rates coupled with erratic semi-arid rainfall. Objectives were to calibrate and validate DSSAT-CSM (Decision Support System for Agro-technology Transfer Cropping Systems Model) and apply the model to assess yield, water productivity, and irrigation water use efficiency of water limited cropping systems in western Kansas. The cropping systems evaluated included continuous corn, wheat, and grain sorghum in corn-wheat, corn-wheat-grain sorghum, corn-wheat-grain sorghum-corn rotation systems. Results showed that the model adequately reproduced observed growth and development of all three crops. Corn under full irrigation produced more yield compared to deficit irrigated corn as expected. However, grain water productivity of corn under full and deficit irrigation were not substantially different. Under deficit irrigation, corn in rotation produced higher yields and crop water productivity compared to that of continuous corn. Yield and water productivity of continuous wheat was higher than that of wheat in rotation. In addition, predicted wheat yields under deficit irrigation were as high as those under full irrigation which implies that deficit irrigation might be the optimum option for producers with limited well capacities. Deficit irrigation substantially improved yields and water productivities of grain sorghum under both continuous and crop rotations. Predicted long–term average grain sorghum yields under crop rotation were higher than those of continuous grain sorghum. Grain sorghum should be grown in rotation under deficit irrigation. This research did not simulate the impacts of pests, weeds and diseases, hail and freeze damage on crop yield. However, the study still identifies cropping systems that are more likely to produce highest water productivity.