Reduction of effluent nitrogen and phosphorus from paddy fields

In order to reduce nitrogen and phosphorous loads flowing out from paddy fields, the effects of no-puddling and coated fertilizer were examined. First, pot examination was performed in order to clarify the influence of puddling on nitrogen and phosphorous concentration in the ponding water on paddy soils. The experiment was conducted three times under the condition of puddling or no-puddling, as the condition of fertilizing or no-fertilizing. By using the result, the storage term of the ponding water after puddling was considered for four soils.Next, a field experiment was conducted to compare the effect of the coated urea division with the conventionally cultivated division and the no-fertilizing division. By using coated urea, it was possible to reduce the amount of nitrogen fertilizer to about 60% of the conventionally cultivated division; thus, it showed clearly that coated urea has a great effect on reducing effluent nitrogen. Although there was less yield of hulled rice than that of the conventionally cultivated division, it was proven by the palatability test that the flavor of the rice from the coated urea division was better than that of the conventionally cultivated division rice.