Influence of fertilizer reduction on effluent loads from paddy fields using a side fertilizer rice transplanter and a single application of fertilizer to a nursery box

In the irrigation period from 1999 to 2001, the influence of fertilizer reduction on outflow loads has been examined. Phosphorus fertilizer is applied using a side fertilizer rice transplanter and coated nitrogen fertilizer is treated in a nursery box just one time to reduce the mass of fertilizer. Phosphorus and Nitrogen concentration in standing water and percolated water of the reduced fertilizer division is less than that of the conventional division. Suface and subsurface loads of phosphorus and nitrogen from the reduced fertilizer division are less than those of the conventional division. Outflow loads from the reduced fertilizer division are reduced in comparison to the conventional division by about 0.6-1kg/ha in phosphorus, 4-6kg/ha in nitrogen, respectively. It seems to be effective for reducing outflow loads from paddy fields that the amount of fertilizer is reduced by using a side fertilizer rice transplanter and a nursery box.