Zone tillage depth affects yield and economics of corn silage production
Increasing numbers of dairies in northeastern United States are classified as confined animal feeding operations (CAFOs). Many dairy farmers in New York (NY) abandoned conventional and adopted zone tillage (ZT) in 4-yr corn (Zea mays L.) silage-alfalfa (Medicago sativa L.) rotations on highly erodible land to comply with NY CAFO plans. Farmers now question optimum ZT depth because of increased diesel costs. The objective of this 2-yr NY study was to determine optimum ZT depth for corn silage in continuous corn and first-year corn following alfalfa. The ZT depth (with attached Aerway implement), evaluated at 0, 18, and 36 cm, did not affect surface residue (~34%), plant densities (71,605–73,998 plants ha–1), and dry matter (DM) accumulation at the 12th leaf stage (334–365 g m–2). Significant contrasts were observed between 18 vs. 0 cm for DM yield (19.9 and 18.7 Mg ha–1) and N uptake (236 and 219 kg ha–1, respectively), but not between 18 vs. 36 cm (19.7 Mg ha–1 and 237 kg ha–1).The ZT depth did not affect silage quality. Partial budget analyses indicate that reducing ZT depth from 36 to 18 cm increases profit by ~$30 ha–1 because of decreased labor ($1.48 ha–1), fuel ($5.88 ha–1), and equipment repair and maintenance costs ($3.01 ha–1) and increased return from higher yield ($21.98 ha–1, offset by $2.57 ha–1 increased harvest cost). We recommend an 18-cm ZT depth for corn silage in a 4-yr corn silage-alfalfa rotation on silt loam soils in northeastern United States.