Tillage and Rotation Effects on Corn Yield Response to Fertilizer Nitrogen on Aqualf Soils
- John A. Stecker ,
- Darly D. Buchholz,
- Roger G. Hanson,
- Nyle C. Wollenhaupt and
- Kent A. McVay
- D ep. of Agronomy, 144 Mumford Hall, Univ. of Missouri, Columbia, MO 65211
E xt. Agric. and Natural Resources, 119 Umberger Hall, Kansas State Univ., Univ., Manhattan, KS 6650
T ropical Soils Management CRSP, Box 7113, North Carolina State Univ., Raleigh, NC 27695
D ep. of Soil Science, 1525 Observatory Dr., Univ. of Wisconsin, Madison, WI 5370
D ep. of Agronomy, Univ. of Georgia, Athens GA 30602
Fertilizer N recommendations are often increased for no-till corn (Zea mays L.) relative to conventionally tilled corn. A comparison of relative yield responses to fertilizer N is lacking for continuous corn and corn following soybean [Glycine max (L.) Merr.] when grown with conventional and no-tillage systems on poorly drained claypan soils. Field studies spanning 5 site-years were conducted on somewhat poorly (Udollic Ochraqualf) and poorly (Mollic AIbaqualf) drained claypan soils in central and northeast Missouri. The experimental design was a split-split plot, where whole plots were tillage system (chisel-disk and no-till) and subplots were rotation (continuous corn and corn following soybean). Subsubplots were N rates of 0, 67, 135, 202, and 269 kg ha−1, applied preplant as either anhydrous NH3 (82-0-0 N-P-K) or knife-injected urea-ammonium nitrate (UAN) solution (32-0-0). Corn grain yield response to fertilizer N was described by quadratic and quadraticplateau models that had similar R2 values. With continuous corn, both models predicted no-till to require 14 to 17 kg ha−1 (5–7%) less fertilizer N for maximum yield and profit than the chisel-disk system. The predicted maximum no-till grain yield was 0.34 Mg ha−1 less than the chisel-disk system. No-till corn following soybean required an average additional 17 kg N ha−1 (8%) for maximum yield (quadratic model) and 45 kg N ha−1 (35%) for maximum profit (quadratic-plateau) than the chisel-disk system. The average maximum yield for no-till corn following soybean was 0.20 Mg ha−1 less than the chisel-disk system. Apparent N credit for corn following soybean varied from 0 to 159 kg ha−1. With the quadratic model, the average N credit was 54 kg ha−1 for the chisel-disk system and 24 kg ha−1 for no-till. Decreased no-till corn yields that required equal or greater fertilizer N indicate at least a short-term economic disadvantage for this tillage system on these poorly drained soils.
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