ABSTRACT:
Soil erosion in Indonesia has occurred at an alarming rate. A management challenge arises not only because of the lack of understanding of soil erosion processes and lack of data, but also due to difficulties in the application of soil erosion models. The objectives here are to measure erosion rates and sediment yields in a watershed in West Java using the Agricultural Non-point Source Pollution (AGNPS) model, to document rates of erosion from forestry and agroforestry land uses in the basin, and to compare soil erosion rates calculated by the AGNPS and Universal Soil Loss Equation (USLE) models. The method was to use both primary and secondary data as inputs to the AGNPS and USLE models, as well as field observations to compare the outputs from the two models with conditions in the field. The AGNPS model measured about half of the erosion rate predicted by the USLE. However, the AGNPS output appears to be more realistic. The erosion rates of the study area (2592 ha; 6.402 acres) were 95 and 103 ton/ha/yr (8,480 and 9,205 ton/acre/yr) in 1991 and 1992. The sediment yields were 99,630 ha/year (246,000 ton/yr) in 1991, and 108,135 ha (267,000 ton/yr) in 1992. The t-test regarding soil erosion in forested and agroforestry areas demonstrates that the difference in soil erosion rates is not statistically significant (α =0.05). Based on this finding, agroforestry is an excellent choice of land use to minimize soil erosion rates.
Footnotes
Ambar Kusumandari is a junior lecturer at Gadjah Mada University, Faculty of Forestry, Bulaksumur, Yogyakarta, Indonesia; Bruce Mitchell is a professor at the University of Waterloo, Department of Geography, Faculty of Environmental Studies, Waterloo, Ontario, CANADA.
- Copyright 1997 by the Soil and Water Conservation Society
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