Effects of land use and parent materials on trace elements accumulation in topsoil.

To determine the effects of parent material and land use on the concentration of trace elements in the agricultural topsoil of Guizhou Province, China, a total of 584 agricultural topsoil samples were collected in a typical region. The results indicate that the contents of trace elements (As, Cd, Cr, Hg, and Pb) in agricultural soils were greater than in the uncultivated soils, and the paddy fields exhibited higher contents of trace elements than dry lands. The enrichments of most trace elements in agricultural topsoil derived from carbonate rock were more serious. In paddy fields, Cd, Cr, and As showed positive relationships with soil organic matter ( < 0.01) but were not affected by pH, carbon-to-nitrogen (C/N) ratio, and clay ( > 0.05). Lead and Hg formed the second component in principal component analysis (PCA) and were closely related to pH and clay content. In dry lands, the trace elements were well correlated with pH, C/N, and clay ( < 0.05). Analysis of PCA and correlation showed that Cd, Cr, and Hg were mainly derived from inorganic fertilizers, whereas Pb and As were primarily from organic manures. These results suggest that the effect of anthropogenic activities on paddy fields is more serious than on dry lands. Parent materials not only serve as sources of soil trace elements but also control the loss and accumulation of trace elements by affecting soil physicochemical properties, especially in dry lands.

[Characteristic research on soil nutrient of root of Pseudostellaria heterophylla root zone and non-root zone in different planting patterns].

OBJECTIVE: To research the influence of Pseudostellaria heterophylla planting patterns on soil nutrients. METHODS: The root zone and non-root zone soil nutrient status were analyzed, which included the crop rotation, intercropping, relay cropping, 1-year planting, 3-year planting, 6-year planting and 10-year planting. RESULTS: The results showed that there were differences in the soil nutrient of root zone among different planting patterns. The soil nutrient of root zone in seven different planting patterns were all significantly higher than that of non-root zone soil. And the soil nutrients of root zone showed a significant enrichment. The enrichment ratio of total K and Olsen K in 6-year and 10-year planting were both negative value, which indicated that the soil potassium was deficiency. The average pH value of root zone was 0.32 lower than that of non-root zone. There was a significant positive correlation between the organic matter value and the total nitrogen content in root zone and non-root zone (P < 0.01). The soil nutrients were high in crop rotation and intercropping, it would he helpful to improve soil quality and absorption to nutrient. CONCLUSION: The reasonable application of nitrogen fertilizer ,organic fertilizer and potash fertilizer can significantly increase the organic matter content in soil ,and it will help to retain the fertilizer capacity of soil.