四国地域における農地管理の粗放化に伴う土壌侵食の変動評価

概要

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Soil erosion from fields was investigated in hilly lands in Shikoku where agricultural practices are becoming shorthanded. As the results, soil loss calculated for terraced paddy fields and upland fields was about 3 t ha^<-1> y^<-1> and 8 t ha^<-1> y^<-1>, respectively. Those values were the sum of soil loss of appearance (less than 1 t ha^<-1> y^<-1>) and average soil mass returned to the field. Large soil loss (about 90 t ha^<-1> y^<-1>) was calculated to occur within several years immediately after the abandonment of fields. Though soil loss did not largely increase in fields which changed to mowing grass fields (about 12 t ha^<-1> y^<-1>), there was a significant increase in mowing grass fields which change to wild fields (about 40 t ha^<-1> y^<-1>). Soil loss decreased in wild fields which had changed to be stable (about 10 t ha^<-1> y^<-1>). The soil losses measured in abandoned fields were larger than those observed in the frame plot measurement. Surface runoff intruding from zones above the fields was regarded as one of the main causes for soil erosion. To estimate the potential soil erosion on fields when they are abandoned, the Universal Soil Loss Equation (USLE) was revised by the addition of a term related to the erosion caused by intrusive surface water runoff. Using the new equation, the soil loss caused by abandonment was properly estimated.
社団法人日本土壌肥料学会の論文
1998-06-05