Main
plots consist of one of three levels of corn residue removal (RR: full, partial, and none); split plots were two tillage
systems (T: chisel tilled and no-till) and split–split plots were four N fertilizer rates (Nr: 67, 134, 201, and
268 kg N ha−1). The highest TC stocks were found under no-till without residue removal; removing any residue
under no-till lowered TC to the levels found under chisel tillage. Removing residue in tilled soils produced higher
TC values similar to the levels foundwith no residue removal and no-till. Residue removal tended to lower P and
lowered K and EC in the surface 15 cmsoil. Tillage decreased the N and K stocks in the surface soil. Increasing the
rate ofNfertilizer lowered P, K, and pH, generally in an increasing, curvilinearmanner, but the response of ECwas
concave, increasing at the highest N rate used. These responses were closely related to corn grain yields, indicating
that the amount of nutrient removed by harvest of grain and residue and the amount of residue retained after
harvest affect TC and nutrient stocks in Illinois soils. This information will help producers and policy makers to
make better decisions regarding the feasibility of harvesting corn residue, and on agronomic practices that
might accompany residue removal in order to prevent soil nutrient depletion.
Mainplots consist of one of three levels of corn residue removal (RR: full, partial, and none); split plots were two tillagesystems (T: chisel tilled and no-till) and split–split plots were four N fertilizer rates (Nr: 67, 134, 201, and268 kg N ha−1). The highest TC stocks were found under no-till without residue removal; removing any residueunder no-till lowered TC to the levels found under chisel tillage. Removing residue in tilled soils produced higherTC values similar to the levels foundwith no residue removal and no-till. Residue removal tended to lower P andlowered K and EC in the surface 15 cmsoil. Tillage decreased the N and K stocks in the surface soil. Increasing therate ofNfertilizer lowered P, K, and pH, generally in an increasing, curvilinearmanner, but the response of ECwasconcave, increasing at the highest N rate used. These responses were closely related to corn grain yields, indicatingthat the amount of nutrient removed by harvest of grain and residue and the amount of residue retained afterharvest affect TC and nutrient stocks in Illinois soils. This information will help producers and policy makers tomake better decisions regarding the feasibility of harvesting corn residue, and on agronomic practices thatmight accompany residue removal in order to prevent soil nutrient depletion.
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