Effect of soil bulk density on hydrolysis of surface-applied urea in unsaturated soils |
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Authors: | NK Savant AF James GH McClellan |
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Affiliation: | (1) Fertilizer Technology Division, International Fertilizer Development Center, PO Box 2040, 35662 Muscle Shoals, AL, USA |
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Abstract: | In situ hydrolysis of broadcast urea occurs in unsaturated soils with different bulk densities. The effect of increasing soil bulk densities on the hydrolysis of urea was studied in open and in covered unsaturated soil columns incubated at 30°C. An increase in bulk density from 0.8 to 1.4 Mg/m3 markedly increased the hydrolysis of surface-applied urea in soils containing water > 6% up to near field capacity. Increased diffusion of urea to sorbed soil urease with an increase in bulk density may have enhanced formation of urease-urea complexes and therefore increased the hydrolysis. As urea diffused farther in more dense soils, the retarding effects of high urea concentration gradients on the hydrolysis probably decreased. In light-textured soils, increases in the bulk density had no apparent effect on the hydrolysis of surface-applied urea when evaporation occurred. |
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Keywords: | urea hydrolysis bulk density urea diffusion soil urease |
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