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-tilla ge practices with continuous corn (Zea mays L.) because they fear that phenological development, stand establishment, and grain yield will b e reduced compared with moldboard or chisel plowing. Mechanical remova l of in-row residue at planting may reduce or eliminate these problems . The objectives of this research were to determine the effects of sur face crop residue and planter attachments on in-row cover, seed placem ent, plant density, grain yield, and grain moisture content of no-till age corn, and to determine if these effects changed with time. Three p ostharvest residue levels, residue removed, normal, and double, were c ompared from 1984 through 1990 on Rozetta and Palsgrove silt loam soil s 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 yie ld. For the period 1984 to 1990, yield differences due to crop residue levels and in-row residue removal techniques could not be declared st atistically 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 ca n 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-til l corn production.