UREA HYDROLYSIS IN WETLAND SOIL AMENDED WITH SESBANIA-ACULEATA GREEN MANURE AND RICE STRAW

The effect of incorporating sesbania and rice straw and of period of decomposition on urea hydrolysis was studied in a wetland soil under laboratory conditions. Urea hydrolysis proceeded more rapidly in the crop residue-amended soil than in the control soil, and increased with increases in the rate of addition of crop residues and with longer periods of decomposition. Irrespective of amendment treatment, urea hydrolysis followed first-order reaction kinetics, and rate constants in the unamended soil ranged from 0.021 to 0.024 h-1 after urea application of 200 mug N g-1 soil. In the amended soil, hydrolysis rates ranged from 0.033 to 0.149 h-1 with sesbania and 0.071 and 0.250 h-1 with rice straw, depending on the length of decomposition period.