Skip to main content
ARS Home » Plains Area » Bushland, Texas » Conservation and Production Research Laboratory » Soil and Water Management Research » Research » Publications at this Location » Publication #330829
Title: Assessing deficit irrigation strategies for corn using simulation.

Author
item KISEKKA, ISAYA - Kansas State University Extension Center
item AGUILAR, JONATHAN - Kansas State University Extension Center
item ROGERS, DANNY - Kansas State University
item HOLMAN, JOHNATHON - Kansas State University Extension Center
item O'BRIEN, DAN - Kansas State University Extension Center
item KLOCKE, NORMAN - Kansas State University Extension Center

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/20/2015
Publication Date: 11/10/2015
Citation: Kisekka, I., Aguilar, J., Rogers, D., Holman, J., O'Brien, D., Klocke, N. 2015. Analysis of returns above variable costs for management of verticillium wilt in cotton. Transactions of the ASABE. 59(1):303-317.

Interpretive Summary: Declining groundwater levels in the Ogallala aquifer resulted in diminished well capacities that eventually become incapable of meeting full crop water needs. Therefore, producers need recommendations for deficit irrigation strategies that can maximize net returns in most years under low well capacities. Scientists from Kanas State University in the ARS led Ogallala Aquifer Program calibrated corn crop growth model and used the calibrated model to simulate grain yields under different management schemes. Irrigation scheduling based on a 50% plant available water threshold maximized net returns compared to initiating irrigation at greater soil water content. Having soil water in the top 1.2 m of the soil profile between 0% and 25% depleted at planting maximized net return. Terminating irrigation 90 or 95 days after planting also maximized net returns. These results are of interest to corn producers in areas with low well capacity where water conservation is essential for a successful crop.

Technical Abstract: Declining groundwater levels in the Ogallala aquifer due to withdrawals exceeding annual recharge result in diminished well capacities that eventually become incapable of meeting full crop water needs. Producers need recommendations for deficit irrigation strategies that can maximize net returns in most years under low well capacities. The objectives of this study were to (1) calibrate and validate the CERES Maize model in DSSAT CSM v4.6 under southwest Kansas soils and climatic conditions and (2) apply the calibrated model to assess three factors related to irrigation management: (i) the optimum plant available water threshold to initiate irrigation for maximizing net returns, (ii) the effect of percentage soil water depletion at planting on yield, seasonal transpiration, water productivity, extractable soil water at maturity, and net returns, and (iii) the effect of late irrigation season termination on extractable soil water at physiological maturity, yield, and net returns. The CERES Maize model in DSSAT CSM v4.6 in conjunction with short term experimental data and 63 years (1950 to 2013) of historical weather data were used in this study. The calibrated model was able to predict end of season grain yield with acceptable accuracy (NSE greater than 0.9, 0.13 less than %RMSE less than 0.19), indicating that the model could be used for assessing alternative management strategies for optimizing the use of limited water for irrigating corn in southwest Kansas. Irrigation scheduling based on a 50% plant available water threshold maximized net returns compared to initiating irrigation at greater soil water content at corn prices ranging from $0.10 to $0.26 per kg. Accounting for inter annual variations in weather and irrigation downtime due to repairs, 14 to 17 irrigation applications of 25 mm of water each would be needed to maintain soil water at 50% of plant available water during the season. Having soil water in the top 1.2 m of the soil profile between 0% and 25% depleted at planting maximized net returns, although it also resulted in more extractable soil water at physiological maturity. Terminating irrigation 90 or 95 days after planting depending on corn price maximized net returns and resulted in the lowest amount of extractable soil water at physiological maturity, implying that opportunities exist to mine stored soil water toward the end of the season even under deficit irrigation. We recommend that late season irrigation termination be done in conjunction with soil water monitoring and management allowable depletion techniques to minimize potential reduction in yields. Before adopting any of the management strategies assessed in this study, producers should consider the unique yield potential constraints for their farm. The concepts explored in this analysis, which combined experimental data, computer simulation, and long term weather data to generate optimum management recommendations, could be applied in other areas with constrained water supplies for irrigation.