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