Irrigation management impacts on corn yield and nitrate leaching
Vasudha Sharma
Coarse-textured soils in Minnesota have limited water holding capacity which makes irrigation essential to obtain ideal yields for corn, however, excess irrigation has the potential to contaminate ground and surface water sources through deep seepage of applied fertilizers, making irrigation management critical. The objective of this study was to evaluate the impact of different strategies for agricultural irrigation water management on corn grain yield and nitrate leaching losses. In this three-year study (2019-2021), four irrigation scheduling strategies, (i) soil moisture monitoring using soil moisture sensors (SM), (ii) checkbook method of irrigation scheduling (CB), irrigation management assistant tool (IMA) and (iv) EPIC model auto-irrigation (EPIC) were compared under continuous corn cropping system at two sites in Central Minnesota, Becker and Westport sites.
Overall, in comparison to the CB method (highest irrigation method), SM, IMA, and EPIC methods recommended 2.58%, 51.05%, and 9.27% less water in irrigation respectively. In terms of grain yield, no significant differences were observed between SM, CB, IMA, and EPIC irrigation treatments in the 2019 and 2020 growing seasons at the Becker site. However, in the drier 2021 season, a grain yield loss of 30%, 27%, and 21% was observed under IMA when compared to SM, CB and EPIC methods, respectively, at the Becker site. At the Westport site, on average, no significant difference in yield was obtained between SM, CB, and EPIC, however, yield under IMA treatment was significantly lower (12%) than CB.
The results suggest that nitrate leaching losses can be reduced by altering the rate and frequency of irrigation. Results from this study can aid in the adoption and further development of less labor-intensive and more accurate methods of irrigation scheduling in coarse-textured soils of Minnesota. This study would further help corn growers in Minnesota to decide which irrigation scheduling method would be appropriate for their irrigation management.
