Interseeded alfalfa reduces soil and nutrient runoff losses during and after corn silage production

Interseeding alfalfa (Medicago sativa L.) into corn (Zea mays L.) harvested for silage is a method of establishing alfalfa that can increase overall forage production and may reduce the risk of soil and nutrient losses during and after corn silage production. In this study, rainfall simulations were carried out in southwest Wisconsin, United States, to assess the runoff reduction benefits of alfalfa interseeded into silage corn. Simulations were conducted at three times: within three weeks of crop planting in early June, October following corn silage harvest, and the following April during alfalfa growth resumption. Compared to corn silage grown without an interseeded crop and followed by spring-seeded alfalfa, interseeded corn/alfalfa reduced losses of total suspended solids by 49% to 87%, total nitrogen (N) by 37% to 74%, and total phosphorus (P) by 37% to 81% across the rainfall simulations. Additionally, total runoff volume and losses of dissolved solids, dissolved P, and nitrate (NO3-) were reduced in at least one simulation event. Interseeded alfalfa enhanced total ground cover by 48% to 70% at the simulation times, which was negatively related to losses of total suspended solids.