Residue and agronomic management to reduce the continuous corn yield penalty

Accelerated residue degradation and nutrient cycling will be necessary to maximize yield potential in corn (Zea mays L.) grown continuously and in other high-volume residue situations. This study aimed to test if residue management and agronomic inputs could lessen the continuous corn yield penalty (CCYP) compared to a corn following soybean [Glycine max (L.) Merr.] rotation. Field experiments conducted during 2017 and 2018 at Champaign, IL, USA compared plots of 15th year continuous corn to long-term corn-soybean rotation plots. The previous year’s corn crop residue was either downsized (chopped) or harvested with standard knife rollers, with further chemical management of either a biocatalyst or ammonium sulfate, or it was left untreated. A standard management system of 79,000 plants ha⁻¹ and a base rate of nitrogen fertilizer was compared to an intensive management system of 111,000 plants ha⁻¹ with additional fertilizer and a foliar fungicide. Although continuous corn cropping stress was not detected until R2 (kernel blister stage), the CCYP was 1.30 Mg ha⁻¹. Sizing residue enhanced overwinter residue decomposition and increased yield by 0.31 Mg ha⁻¹ regardless of rotation and by 0.53 Mg ha⁻¹ in continuous corn. Intensive inputs in combination with residue sizing increased grain yield of continuous corn by 1.15 Mg ha⁻¹ over standard-management rotated yields. Therefore, combining mechanical and agronomic managements can reduce corn residue and the CCYP for more sustainable crop production.