SURFACE RESIDUE AND IN-ROW TREATMENT EFFECTS ON LONG-TERM NO-TILLAGE CONTINUOUS CORN

Many farmers in the northern Corn Belt are reluctant to adopt no-tillage practices with continuous corn (Zea mays L.) because they fear that phenological development, stand establishment, and grain yield will be reduced compared with moldboard or chisel plowing. Mechanical removal of in-row residue at planting may reduce or eliminate these problems. The objectives of this research were to determine the effects of surface crop residue and planter attachments on in-row cover, seed placement, plant density, grain yield, and grain moisture content of no-tillage corn, and to determine if these effects changed with time. Three postharvest residue levels, residue removed, normal, and double, were compared from 1984 through 1990 on Rozetta and Palsgrove silt loam soils in southwestern Wisconsin. Average grain yields over the 7-yr period ranged from 3.7 to 10.8 Mg ha-1. Seasonal effects, presumably due to weather conditions, accounted for >90% of the variability in grain yield. For the period 1984 to 1990, yield differences due to crop residue levels and in-row residue removal techniques could not be declared statistically significant at the 5% level, given the limited size of the study. However, average yields with normal residue were 0.44 Mg ha-1 greater than where residues were removed. Because such a difference can be agronomically important, additional research seems warranted. In-row residue affected planting depth and stand density emphasizing that uniform seeding depth is particularly important for successful no-till corn production.