Nitrogen fertilizer improves no-till soybean seed yield

Abstract

No-tillage (NT) soybean [Glycine max (L.) Merr.] following corn (Zea mays L.) is a common practice in the United States. It reduces production costs associated with tillage such as labor, fuel, and equipment, in addition to providing environmental benefits such as reduced erosion and carbon emissions. However, in some situations, NT soybean seed yield can be reduced compared to conventional tillage (CT). The objectives of this study were to (i) quantify the effects of nitrogen, corn residue management, and tillage on soybean seed yield, and (ii) recommend optimal residue and nitrogen (N) management strategies for NT soybean following corn. The study was conducted at the University of Wisconsin-Madison Arlington Agricultural Research Station near Arlington, WI, during the 2022 and 2023 growing seasons. Treatments were tested in a randomized complete block design with four replicates. Treatments were combinations of NT, CT, N fertilizer application, and corn residue management (removed, chopped, or none). Soybean seed yield was not affected by removing corn residue. Applying 30 lbs N acre⁻¹ prior to NT planting soybean into corn residue and CT increased seed yield by 4.1 bu acre⁻¹ (6.1%) and 5.3 bu acre⁻¹ (7.8%), respectively compared to NT soybean planted into corn residue. The addition of a low rate of spring N can be a tool for producers to increase NT soybean seed yield rather than performing tillage.