無代かきおよび育苗箱全量施肥栽培水田における流出負荷量の削減

概要

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Various analytical items of surface water, subsurface water, irrigation water and rain water were measured in experimental plots at the university farm. Three experimental plots were set up: 1. A conventional plot, where ordinary plowing and puddling were practiced with the application of conventional doses of N-P-K as the basal and two top-dressings. 2. No-puddling plot, where plowing, but no puddling, was practiced before transplanting and all the N was applied to the nursery box in the form of a coated fertilizer (containing 30% N and 10% K_2O), with P and K supplemented as the basal before plowing. 3. No-fertilizer plot, where plowing and puddling were practiced but no fertilizers nor pesticides were applied. The surface effluent loads of the no-puddling plot were 31% for T-N, 25% for T-P, 55% for T-COD, 94% for BOD and 27% for SS as compared with those of the conventional plot. The subsurface effluent loads of the no-puddling plot were, likewise, 52% for D-N, 87% for D-P, 78% for D-COD and 89% for BOD. The effluent loads (N, P, COD, BOD, SS) of the conventional plot were greater than the incoming loads, where those of the no-puddling plot were greater for P, COD and BOD but smaller for N and SS than the incoming loads. Thus, the nursery box application of coated fertilizer in combination with no-puddling appeared to be effective in reducing the effluent N and SS loads from paddy fields.
社団法人日本土壌肥料学会の論文
2000-08-05