Release of Nitrogen from Crimson Clover Residue under Two Tillage Systems

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Abstract
The N contained in winter cover crops (particularly legumes) is a potentially important source of N for succeeding crops. The purpose of this study was to determine N release from crimson clover (Trifolium incarnatum L.) residue under no‐tillage and conventional tillage conditions. Residues contained in nylon mesh (53 µm) bags placed either on the surface of no‐tillage plots or buried at plowlayer depth in conventional tillage plots were removed for dry matter, C, and N determinations at 1, 2, 4, 8, and 16 weeks after placement in mid‐May. The rate of N disappearance was more rapid under conventional than no‐tillage conditions. The percentage of initial residue N remaining at 4 and 16 weeks under conventional tillage conditions was 40 and 31, respectively. The corresponding values for no‐tillage were 63 and 36% at 4 and 16 weeks. The C/N ratio of the residue remained relatively unchanged over the 16‐week period under no‐tillage conditions. However, under conventional tillage conditions, the C/N ratio declined from 15.9 to 12.7. Under humid, subtropical conditions, release of N from both surface and buried residue from winter legumes, is sufficiently rapid to be of significant benefit to the summer crop.
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  • Georgia Agric. Exp. Stn.