低丘红壤肥力的时空变异

利用地统计学方法研究了我国中亚热带低丘红壤区土壤肥力的时空变异。1 985年和 1 997年 ,在 1 .35km2 的区域内以 1 0 0m× 1 0 0m的网格采集了 1 0 5个表层土壤样品。分析结果表明土壤肥力性质具有较大的空间变异 ,速效磷的变异系数最高 ,而pH的变异系数最低。土壤pH空间相关性强 ,而有机质、速效磷和速效钾空间相关性中等。未开垦前 ,土壤肥力性质的空间相关间距大于等于红壤丘陵的直径 ;开垦 1 2年后 ,土壤肥力性质的相关间距减少 ,其中pH和速效钾的相关间距与红壤丘陵的半径相当。土壤肥力性质及其变化值的克立格插值结果显示出一定的空间相似性 ,说明地统计学方法可以同时分析土壤肥力在时间和空间上的变异

SPATIO-TEMPORAL VARIABILITY OF RED SOIL FERTILITY IN LOW HILL REGION

Research to address spatio-temporal variability of soil chemical properties was conducted with geostatistical method in low hill region in subtropical China. Soil samples from 0-to 15-cm depth were collected at 105 locations on a 100-by 100-m grid within a 1.35 km 2 field in 1985 and again in 1997. Soil properties varied sharply, with available P showing the highest CV and soil pH the lowest. Geostatistical analysis revealed that all the soil chemical properties and their changes between the two sampling time were spatial-structured. The nugget-to-sill ratio showed a strong spatial dependence for soil pH, and a moderate one for other properties. The ranges for soil properties sampled in 1985 were roughly equal or larger than the diameter of the hills. Changing the land use patterns decreased the ranges for soil chemical properties. The ranges for soil pH and available K were about the radius of hills. The contour map by kriging showed, to a certain extent, a spatial similarity among the estimated values for soil properties in and between the two sampling time. This showed the kridging can be used to analyze the spatio-temporal variability of soil properties.