Title: Nutrient properties of soils in typical degraded hilly land in South China
Abstract: Discussed the nutrient properties in the soils of typical degraded hilly land in south China. Degraded hilly lands are caused by long-term intensive human disturbance. They are now partly cultivated mainly as fruit farms and partly abandoned with little disturbance as a result of economic development in rural areas. In this study, 6 small catchments, each approximately 5~8 hm2, were sampled. One or 2 soil profiles in each catchment were dug up to 1 m depth and soils were taken across the profiles. Each catchment was divided into upper, middle and foot parts. Each part was further sub-divided into left, middle and right positions. In each position, a mixed soil sample was taken consisting of 10 small soil cores, each with diameter of 3 cm and depth of 20 cm. Soil samples were analyzed for major nutrients such as organic matter (OM), total nitrogen, total phosphorus, available phosphorus, available potassium, C/N ratio, exchangeable calcium and exchangeable magnesium, including pH (water extract). Mean organic matter content of surface soil was determined to be 18.03 g/kg and total nitrogen 0.86 g/kg. Soil pH values ranged from 4.06 to 4.57 with mean of 4.25. Available nutrients were generally low, particularly for available phosphorus. Across the profile, both organic matter and total nitrogen decreased sharply with increasing depth, reflecting the features of grassy vegetation. Soil pH, as well as total phosphorus, increased with the increasing depth. The available nutrients exhibited a bi-directional gradient, that is, low in the middle layer and high in both surface layer and deep layer. On the hill slope, soil OM, total nitrogen and available phosphorus all decreased with altitude increasing. Total phosphorus and exchangeable potassium, calcium and magnesium were all bi-directional, that is, low in the middle position and high in both hill top and hill foot. OM and total nitrogen, both as bio-originated, were significantly correlated to each other. pH was negatively significantly correlated to OM in the profile samples, which was attributed to the reverse trend across the profile. However no correlation was found between OM and pH in the surface samples. Calcium and magnesium, both having similar adsorption characteristics, were highly correlated to each other. Cluster analysis and principal component analysis (PCA) were conducted on the surface soil data. It was demonstrated that most soils were similar with regards to the soil nutrient content. Most soils were combined to a group at a rather low cluster level, regardless of their positions in the soil profiles. However, many exceptions were found for those soils which had a high nutrient content index. These nutrient special soils, mainly situated at the foot or middle of the hill, and absent from the top of the hill, may partly account for the growth of particular vegetation on these areas of the hill. Cluster analysis and PCA effectively evaluated the similarity of soils from a different viewpoint with significant correlation.
Publication Year: 2003
Publication Date: 2003-01-01
Language: en
Type: article
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Cited By Count: 3
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