Irrigation, carbon amelioration, nitrogen, and stover removal effects on continuous corn

Corn (Zea mays L.) residue or stover is harvested as supplemental feed for livestock and is a potential feedstock for cellulosic biofuels. Limited information is available on corn stover removal effects on grain yield under different irrigation rates, nitrogen (N) fertilizer rates, and practices to maintain soil carbon (C) and minimize soil erosion. We evaluated potential interactions between irrigation rate (full or limited), C amelioration practices (cover crop, surface-applied manure, or no amelioration practice), fertilizer N management (125 or 200 kg N ha⁻¹), and stover removal (residue removal or no residue removal), on no-till continuous corn grain yield located on a silt loam soil in south-central Nebraska (2011–2018). Stover removal increased (P =.0017) grain yield by 1.02 Mg ha⁻¹ and grain N uptake compared with no stover removal. Manure increased corn grain yield by 899 kg ha⁻¹ compared to either the control or cover crop with stover removal while C amelioration practices did not affect grain yield under stover retention. Grain N concentration was higher (P <.0001) with stover removal (13.2 g kg⁻¹) than residue retained (12.7 g kg⁻¹). Partial factor productivity (grain yield/N rate) was highest for manure treatments with residue removal. The farmgate N balance (N applied − N removed) from stover removal was negative, yet grain yield was not affected after eight growing seasons. Grain yield increased with stover removal and manure application resulting in a cost-effective C amelioration practice whereas incorporating a winter cover crop resulted in similar grain yield as the control.