Nitrogen Recovery by Corn from Nitrogen-15 Labeled Wheat Residues and Intact Roots and Soil
1996
Hubbard, Victoria C. | Jordan, Diann
Conservation tillage systems, which maintain crop residues on the soil surface, are becoming more widely used. Crop residues serve as ground cover to reduce soil erosion and act as a sink-source for plant nutrients. A better understanding of the processes involved in crop residue decomposition and N release in these systems is needed to develop more efficient residue and fertility management practices. A greenhouse study was conducted to determine N availability to corn (Zea mays L.) from wheat (Triticum aestivum L.) residues and intact roots and soil as affected by residue placement. Tracer ¹⁵N was used to quantify the N recovered by corn from wheat residues and intact roots and soil. Wheat residues were either surface-placed or incorporated in a Mexico silt loam (fine, montmorillonitic, mesic Udollic Ochraqualf) in pots with intact wheat roots. Residue placement significantly influenced the amount of ¹⁵N recovered by corn from wheat residues but not from intact roots and soil. Corn ¹⁵N recovery was significantly higher from incorporated residues than from surface residues; however, this was not reflected in the dry weight. Corn dry weight was 12% greater from surface residues than from incorporated residues. Higher yield from surface residues was attributed to a more constant optimum soil water content. Contribution from the Missouri Agric. Exp. Stn. Journal Series no. 12 471.
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