Nutrient leaching from field-decomposed corn and soybean residue under simulated rainfall
1993
Havis, R.N. | Alberts, E.E.
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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