Pennycress reduces potential for nutrient loss in Illinois.

Abstract

Nutrient export of nitrogen and phosphorus from row crop agriculture in the Upper US Midwest is a threat to the structure and function of aquatic systems. To meet Environmental Protection Agency (EPA) nutrient reduction goals, the Upper US Midwest needs to implement strategies to reduce nutrient export from agriculture. Studies demonstrate the potential of cover crops to reduce the export of nitrate-nitrogen from the Upper US Midwest. We investigated the impact of the economically viable winter cash cover crop pennycress (Thlaspi arvense) on soil porewater nutrients and soil nutrients and characteristics. We used nine replicated 0.8 ha plots (n = 3 per treatment) at a production scale research farm over 4 years with pennycress and fertilized pennycress (56 kg ha^-1 of urea) treatments compared to a fallow reference. Over the study period, soil porewater nitrate-nitrogen was reduced by 53% in pennycress plots and 34% in fertilized pennycress plots relative to the fallow reference at a depth of 45 cm. Early season establishment was crucial in providing nutrient reduction potential. In 2021, poor pennycress establishment resulted in porewater nitrate-nitrogen concentrations 141% higher than in 2022 with excellent pennycress establishment. Following pennycress termination, soil nitrate-nitrogen was reduced by 24% in pennycress and 26% in fertilized pennycress compared to the fallow reference in the top 30 cm of soil. Following 4 years of pennycress planting, nitrate-nitrogen concentrations were significantly reduced with no broad effect on soil characteristics. We conclude that the novel pennycress crop has potential to reduce nutrient loss from row crop agriculture in the Upper US Midwest.