Corn Residue Rate and Fertilizer N Timing Impacts on Yield Components in No-till Wheat.
Colleen Steele, Larry J. Grabau, and John Grove. Plant and Soil Sciences, University of Kentucky, S-126 ASCN, 500 S Limestone Street, Lexington, KY 40546-0091
The yield of no-till wheat generally declines as the yield of the prior corn crop rises. The objective of this study was to determine the influence of corn residue rate and fertilizer N timing (fall, early spring/Feekes 3, late spring/Feekes 5) on wheat yield components. For two seasons, soft red winter wheat was planted just prior to residue addition at rates of 0, 3.7, 7.5 and 11.2 Mg DM/ha. Fall (0, 45 kg N/ha), early spring (0, 45 kg N/ha) and late spring (45, 90 kg N/ha) N was applied as broadcast ammonium nitrate. Increased residue rate decreased grain yield, while improved N availability generally raised yield. The greater residue rates always reduced kernel mass and plant establishment. Tiller dynamics were greatly influenced by residue rates. With little or no residue, June tiller densities were less than/equal to those of March/April. At the greater residue rates, June Tiller numbers always exceeded those of March/April. Later tillers were associated with the barren heads, smaller kernel numbers/head and smaller kernel mass observed at the greater residue rates.