Jeffrey Vetsch1, Daniel E. Kaiser2 and Gyles Randall1, (1)University of Minnesota, Waseca, MN (2)Soil, Water, and Climate, University of Minnesota, St. Paul, MN
Continuous corn (Zea mays L.) production using conservation tillage often results in less uniform and smaller early season growth along with lower grain yields, especially on poorly drained soils in the northern Corn Belt. The objective of this study was to determine the effects of various combinations and rates of starter fertilizers containing nitrogen, phosphorus and sulfur on continuous corn production in reduced tillage. Field experiments were conducted from 2010 through 2011 on Webster clay loam (Typic Endoaquolls) and Mt. Carroll silt loam (Mollic Hapludalfs) soils. Treatments consisted of a factorial arrangement of rates of three fluid starter fertilizers: 0 and 75 L ha-1 of urea ammonium nitrate (UAN), 0 and 37 L ha-1 of ammonium poly phosphate (APP) and 0, 19, and 37 L ha-1 of ammonium thiosulfate (ATS). The APP was applied (in-furrow) with the seed while UAN and ATS were applied as a dribble band on the soil surface near the row. Generally, N, P and S starter fertilizers increased early growth (plant height and dry matter yield) of V7 corn plants, while minimizing plant to plant variability. Treatment effects on corn grain yield and moisture varied among years and locations. Applying UAN as a surface band, reduced grain moisture in two of four location-years but did not affect grain yield. Applying APP in-furrow increased yields 0.25 Mg ha-1 at one of four location-years. Applying ATS as a surface band increased grain yield about 0.5 Mg ha-1 at two of four location-years. Applying APP and ATS independently or in combination had the greatest likelihood for increasing continuous corn yields in this study.