Soil and nutrient losses from limited-resource farms are major contributors to water-pollution problems in many parts of the world. Research was undertaken to evaluate the feasibility of utilizing vegetable and small fruit crops as major components in farmers' cropping systems to reduce these losses. A 'limited-resource farm' is defined in this research as one that provides a maximum of US$40 000 gross income, and has no off-farm employees. The crops selected were sweet potato (Ipomoea batatas), raspberry and blackberry (Rubus spp.), and soybean (Glycine max). Runoff plots (63.75 m2) were established on a Baxter cherty silt loam (fine, mixed, mesic, Typic Paleudalf) during the 1986 and 1987 growing-seasons from May to September. A total of 19 rainfall events occurred during the 1986 growing-season and 11 in 1987. The eroded sediment was collected using a modified Gerlach-trough method. After total soil loss was determined, the sediment was analyzed for Ca, Mg, and K, extractable P, and micronutrients (Cu, Zn, Fe, and Mn). Rainfall intensity and duration, total runoff volume, organic-matter content, and percent canopy cover were also determined. The results showed that nutrient losses were related to soil loss, and that erosion parameters influenced soil loss and runoff. Significant differences were observed among crops in reducing nutrient losses. Sweet potato, which was planted on 0.15-m ridges, was more effective in controlling nutrient and soil losses than the other crops. This was primarily because of the better canopy cover and the ridges which slowed the flow of water across the slopes. The crops' ability to reduce nutrient losses varied from year to year for most nutrients. However, significant differences among crops and in P concentration in the eroded sediment were observed in both growing-seasons. The type of crop, month of the year, canopy cover, rainfall duration, and slope were found to be significant in contributing to the nutrient losses. © 1990.
