Nutrient Leaching from Field-Decomposed Corn and Soybean Residue under Simulated Rainfall
1993
Havis, Robert N. | Alberts, E Eugene
Quantification of nutrient leaching from crop residue is important in the management of agricultural water quality. This study measured plant matter decay under field conditions, and nutrient (NH₄, PO₄, and NO₃) leaching dynamics and total mass transport from partially decomposed corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] residue under laboratory-scale rainfall simulation. Plant matter decay rates were not significantly different for the two crops during 1 yr of decomposition. The nutrient mass leached (nutrient mass/plant material mass) from soybean residue was, in decreasing order, NH₄-N > NO₃-N > PO₄-P and, from corn residue, NH₄-N > PO₄-P, NO₃-N. More NO₃-N and NH₄-N was leached from soybean residue than from corn residue, but corn residue released more PO₄-P than soybean residue. The fraction of water-soluble nutrient mass in the plant material that was leached under rainfall increased for NO₃, decreased for NH₄, and remained constant for PO₄, as residue decomposed. Equations to simulate nutrient leaching dynamics under simulated rainfall were evaluated and values for model variables were estimated through nonlinear least squares analysis. A hyperbolic equation provided the best model of the total nutrient mass leached during a rainfall event.
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