Capture of surface water runoff for irrigation of corn in western Illinois: Implications for nutrient loss reduction

Abstract

Supplemental irrigation with the runoff from agricultural fields (runoff irrigation) not only has the potential to reuse nutrients in agricultural runoff but could potentially reduce fertilizer input to farms, leading to reduced nutrient export from agricultural fields. A three-year field study designed to evaluate the impact of runoff irrigation on corn (Zea mays) yield and nutrient uptake was conducted in a farmer-operated field at the Metropolitan Water Reclamation District of Greater Chicago (MWRD) site in Fulton County, Illinois. The study comprised three treatments: (1) 50% agronomic nitrogen (N) and phosphorus (P) fertilizer rates with no irrigation (control), (2) 50% agronomic N and P fertilizer rates with irrigation, and (3) 100% agronomic N and P fertilizer with no irrigation. Each treatment was assigned to a 76 m by 18 m plot, planted with corn in 2016, 2017, and 2018. Runoff irrigation increased grain, stover, and total dry matter yields by an average of 38%, 45%, and 27%, respectively, as compared to the control. On average, 50% agronomic fertilizer rate, coupled with runoff irrigation, produced similar grain yields as 100% agronomic fertilizer rate. At the 50% agronomic fertilizer rate, N uptake averaged 231 ± 37 kg N ha^–1 in 2017 and 290 ± 54 kg N ha^–1 in 2018 with irrigation, as compared to 162 ± 36 kg N ha^–1 in 2017 and 179 ± 34 kg N ha^–1 in 2018 without irrigation. Similarly, P uptake was greater with irrigation than without irrigation for the same P fertilizer rate. The fertilizer replacement value (FRV) of the runoff irrigation was estimated to be 73 kg N ha^–1 and 6 kg P ha^–1 in 2018. This represents a potential of reducing N and P fertilizer application rate by 30% and 8%, respectively, by supplemental irrigation without reducing corn yield. The runoff irrigation is a potential best management practice that can be further explored for adoption in Illinois for contributing to the statewide Nutrient Loss Reduction Strategy.