Cumulative deficit irrigation effects on corn (Zea mays, L.) biomass and grain yield

Authors: Benjamin, Joseph; Nielsen, David; Vigil, Merle; Mikha, Maysoon; Calderon, Francisco

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/28/2015
Publication Date: 9/1/2015
Publication URL: http://handle.nal.usda.gov/10113/61914
Citation: Benjamin, J.G., Nielsen, D.C., Vigil, M.F., Mikha, M.M., Calderon, F.J. 2015. Cumulative deficit irrigation effects on corn (Zea mays, L.) biomass and grain yield. Agricultural Water Management. 159/107-114.

Interpretive Summary: Deficit irrigation is sometimes used to cope with dwindling irrigation water supplies or limited water allocations. A six-year study at Akron, Colorado investigated the effects of consecutive years of deficit on soil water use, soil water storage, biomass production, grain yield and water use efficiency in a continuous corn system. In the first year, deficit irrigation and full irrigation had the same grain yield. In subsequent years deficit irrigation reduced grain yield by 20% to 65% relative to full irrigation. Soil water depleted by the crop with deficit irrigation was not replaced during the non-crop period. This resulted in a slow but continual decrease in soil water storage as the number of years of deficit irrigation increased. By the sixth year of the study, deep soil water storage in the remained near the wilting point for the entire growing season with continued deficit irrigation. Water use efficiency declined for deficit irrigation compared with full irrigation over the years. Water use efficiency was the same for deficit and full irrigation at the beginning of the study, but water use efficiency of deficit irrigation declined to only 65% of full irrigation by the sixth year. Deficit irrigation may be an option for short term or emergency situations when insufficient irrigation water is available for full irrigation in one year. However, long-term use of deficit irrigation, without replenishment of stored soil water during the non-cropped period, is detrimental to both corn production and water use efficiency.

Technical Abstract: Deficit irrigation (DI) is sometimes used to cope with dwindling irrigation water supplies or limited water allocations. A six-year study at Akron, Colorado investigated the effects of consecutive years of DI on soil water use, soil water storage, biomass production, grain yield and water use efficiency (WUE) in a continuous corn system. In the first year, DI and full irrigation (FI) had the same grain yield. In the second year, DI reduced grain yield by 20% relative to FI. By the sixth year, continued DI reduced grain yield by 65% compared with FI. Significant increases in soil water storage during the non-crop period occurred in only two years of the study. This resulted in a slow but continual decrease in soil water storage as the years progressed. By the sixth year of the study, soil water storage in the 60- to 90-cm depth remained near the wilting point for the entire growing season under DI. WUE declined for DI compared with FI over the years. WUE was the same for DI and FI at the beginning of the study, but WUE for DI declined to only 65% of FI by the sixth year. DI may be an option for short term or emergency situations when insufficient irrigation water is available for FI in one year. However, long-term use of DI, without replenishment of stored soil water during the non-cropped period, is detrimental to both corn production and water use efficiency.