SOIL NUTRIENTS IN ERODED GRANITIC AREAS OF SOUTH CHINA

Valleys in the hilly areas of South China are intensely cultivated, despite the low nutrient content of the colluvium and alluvium derived from the weathered granite uplands. The uplands undergo varying degrees of soil erosion. Their soils are highly acidic (pH of 4 to 5.5) and deficient in nitrogen and phosphorus (< 5 ppm), but extremely rich in iron (1–5%). The lowland soils generally have a high infiltration capacity and this enhances the leaching of nutrients. Agricultural activities require much liming and application of organic fertilizers (e.g. mud from fishponds, burnt grass, pig refuse), as continuous farming without fallow easily exhausts the nutrient-poor soils. Revegetation of the denuded hillslopes and improvement of the lowland soil fertility are needed to increase crop productivity. [Key words: nutrients, soil erosion, granitic soils, agricultural effects, China.]