Corn production as affected by tillage system and starter fertilizer

Potential agronomic and soil conservation benefits of modified no-till (NT) systems make them appealing for corn (Zea mays L.) production in the northern Corn Belt where adoption of NT has been limited due to yield reductions on these colder soils. A 4-yr (1997-2000) experiment was conducted on a high P- and K-testing Port Byron silt loam (fine silty, mixed, mesic typic Hapludoll) to determine the effects of four tillage systems [no-till (NT), Rawson zone till (ZT), fall strip till (ST), and conventional tillage practice (CT)] on corn production and cone index (Cl; penetrometer resistance) in continuous corn and corn following soybean I Glycine mar (L.) Merr.]. Eight treatments, four tillage systems (main plots) with starter fertilizer at rates of 0 and 168 kg ha(-1) of a 9-10-24, were arranged in a split-plot design with four replicates. Surface residue coverage after planting was maintained at high levels (>40%) with NT, ZT, and ST, whereas coverage averaged only 25% with the CT practice. Cone index during the period of early plant growth was significantly less for the ZT and ST systems compared with the NT and CT systems, but Cl did not exceed 1.3 MPa. Four-year average yields of continuous corn grain ranked according to tillage were CT > ZT = ST > NT. A significant tillage X year interaction indicated equal yields for CT and NT in the first 2 yr but 1.0 to 1.2 Mg ha(-1) less with NT in the last 2 yr. Tillage system did not significantly affect corn grain yields following soybean when averaged across years. Starter fertilizer increased yields by 0.5 Mg ha(-1) on this high-testing soil for all tillage systems in both crop rotations. Surface residue and corn yields following corn and soybean can be optimized using modified NT systems (ZT and ST) and starter fertilizer in these welldrained, loess soils.