Long-term effects of late-summer overseeding of winter rye on corn grain yield and nitrogen balance

Abstract

Winter rye (Secale cereale) overseeded into standing corn (Zea mays L.) on sandy soil controlled NO₃ leaching over the short-term (3 yr). Long-term effects were unknown, so yield and N balance were monitored for an additional 6 yr with and without a rye cover crop under conventional (CT) and no-till (NT) management at six fertilizer N rates. Corn yield was greater with rye cover cropping than without in 6 of the last 7 yr. Response exceeded 1600 kg grain ha^-1 (average 100–200 kg fertilizer N ha^-1) by year 8 (wet following a dry year) and was greater under NT than CT in dry years (years 7 and 9). The response is attributed to improved soil physical properties and N availability. Rye N uptake increased with fertilizer N rate particularly following dry growing seasons, with shoots containing up to 73 kg N ha^-1. Post-harvest topsoil NO₃ was reduced by the rye in all but the initial year, and groundwater NO₃-N concentrations only exceeded 10 mg L^-1 without rye. The overseeding system facilitates utilization of conserved N and reduces movement of NO₃ to groundwater over the long term. Key words: Nitrogen management, Zea mays, Secale cereale, cover crop, soil nitrate, tillage