Nutrient Distribution following Wheat-Residue Dispersal by Combines
1992
Douglas, C. L. | Rasmussen, P. E. | Allmaras, R. R.
Uneven crop residue distribution by a combine may creae non-uniform nutrient distribution in the field long after harvest. Uniform distribution of nutrients across a field has significant impacts on plant growth, soil sampling, fertilizer efficiency, and nutrient loss to surface and subsurface water. This study was conducted to evaluate nonuniformity of N, P, S, and K distribution across a field following combine harvest of soft white winter wheat (Triticum aestivum L.). Twelve self-propelled combines were evaluated in 1983 and 10 in 1984. Each combine passed over an 11-m strip of canvas, divided into 0.94 by 0.91 m segments, which was inserted in a swath cut into the unharvested wheat. Residues deposited on any segment of the canvas were collected and residue distribution and N, P, S, and K content of the residue was determined. Distribution of these four nutrients followed the residue distribution and created cyclic nonuniformity across the landscape. Maximum nonuniformity of nutrient distribution, where 1 = perfect uniformity, ranged from 2.7 to 9.0 for N, 1.9 to 7.7 for S, 2.3 to 9.4 for P, and 1.5 to 6.8 for K. Nutrient distribution was more extreme when wheat was cut closer to the ground. Combine modification to improve chaff distribution significantly improved nutrient distribution. Joint contribution of the USDA-ARS and Oregon State Univ. Agric. Exp. St. Technical Paper no. 9666.
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