|Budget Amount *help
¥3,200,000 (Direct Cost : ¥3,200,000)
Fiscal Year 1999 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1998 : ¥2,400,000 (Direct Cost : ¥2,400,000)
The concentration of surface water, subsurface water, irrigation water and rain measured at the Agricultural Field Laboratory. Three test fields were used. In one test field, fertilizers (N, P and K) were spread over the field and then plowed and puddled as usual. More and more, there was two times the topdressing of fertilizer. For another field, coated fertilizer (containing 30% of nitrogen and 10% of KィイD22ィエD2O) was treated in the nursery box only one time, anD-PィイD22ィエD2OィイD25ィエD2 and KィイD22ィエD2O was spread over the field and then plowed, but was not puddled. The other field was plowed and puddled, but did not use any fertilizer and pesticide.
The surface effluent loads from the no-puddling field were decreased into 31%(T-N), 25%(T-P), 55%(T-COD), 94%(BOD) and 27%(SS) as much as the usual fertilizer field, and subsurface effluent loads from the no-puddling field were decreased into 52%(D-N), 87%(D-P), 78%(D-COD) and 89%(BOD). The nutrient concentration of surface, subsurface, irrigation and rain water were measured in three plots. After the cultivation, the contents of nitrogen and phosphate in the unhulled rice of three plots were measured. The nutrient loads of irrigation water, rain water and fertilizer were counted as incomings into paddy fields. The nutrient loads of surface water, subsurface water and unhulled rice yield were taken into account of the outgoings from paddy fields. In the conventional plot, the incomings of nitrogen and phosphate were greater than outgoings because of too much fertilizers. In the no-puddling plot, incomings and outgoings of nitrogen were balanced because of the smaller amount of fertilizers than the conventional plot.