Agronomic Responses of Continuous Corn to Stover, Tillage, and Nitrogen Management

Abstract

Corn (Zea mays L.) stover removal for biofuel production is expected to increase in the near future. Previous research suggests stover removal is best suited to continuous corn (CC) cropping systems with reduced tillage. However, grain yields in reduced tillage CC systems in the Upper Midwest can be reduced because of cool soil temperatures restricting early‐season growth. Field experiments were conducted over 3 yr at two locations in southern Minnesota with medium‐ and fine‐textured soils to assess the agronomic responses of CC to stover removal, tillage system, and fertilizer N rate. Stover removal and/or tillage increased soil temperature by as much as 4°C, and differences among treatments generally existed until canopy closure. Corn emergence was 6% greater with stover removal in no‐tillage (NT), but was not affected by stover removal in chisel‐tillage (CT) and strip‐tillage (ST). Stover removal increased normalized difference vegetative index (NDVI) at the eight leaf collar stage (V8) by 20 and 13% in NT and ST, respectively, but had no effect on NDVI in CT. Stover removal decreased the economically optimum N rate (EONR) by >12 and >19 kg N ha–1 in NT and ST, respectively, and increased grain yield at the EONR by 7, 9, and 6% in CT, NT, and ST, respectively. These results indicate stover removal can improve short‐term agronomic productivity of moderate‐ to high‐yielding CC on productive soils in the Upper Midwest.