暗きょ排水組織を敷設した海岸砂地畑における窒素溶脱量の推定

概要

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Nitrogen leaching rates were estimated in a vegetable field with a subsurface drainage system in a coastal sand dune area of Shizuoka, Japan, in two different years (1992 and 1994). Nitrate was the major form of nitrogen leached out from the field. Nitrate concentration in the drainage water was high from fall to spring, with the maximum values exceeding 20 mg N L^<-1>. Removal of plastic film covering carrot fields in March might cause the leaching of nitrogen that accumulated in the soil during the carrot growing season during winter. The amount of discharge calculated from working duration of the lifting pumps corresponded well with the amount of percolation separately calculated from precipitation and evapotranspiration. The estimated nitrogen leaching rates showed two seasonal increases in spring and fall, reflecting increases in precipitation and nitrogen concentration in the drainage water. Annual nitrogen leaching rates ranged from 95 to 143 kg N ha^<-1> y^<-1>, which were 26 to 41% of the amount of chemical fertilizer applied. The precipitation in 1994 was extraordinarily low, which resulted in small amount of percolation and a low nitrogen leaching rate. Precipitation greatly affects nitrogen leaching in coastal sand dune areas.
社団法人日本土壌肥料学会の論文
2000-08-05