南方多水塘系统流域土壤养分空间变异特征研究

长江中下游区域湖泊富营养化严重，而农业非点源污染是主要影响因素，了解流域土壤养分空间变化特征，对于采取非点源污染控制措施具有重要意义。借助地理信息系统，利用地统计学中的半变量变异函数研究巢湖流域北岸区域六岔河流域多水塘-沟渠系统中的土壤养分空间变异特征，研究表明，土壤中有机物质（OM）、总氮(TN)、总磷(TP)、氨态氮(NH4-N)、硝态氮(NO3-N)的空间变异函数理论模型均符合球状模型，总磷（TP）、氨态氮（NH4-N）、有机物（OM）空间异质性中结构性变异大于随机变异，在28.8%～44.0%之间；总氮（TN）、硝态氮（NO3-N）空间异质性中结构性变异小于随机变异。机物质（OM）、总氮(TN)、总磷(TP)、氨态氮(NH4-N)、硝态氮(NO3-N)空间自相关范围具有明显的差异，变化范围为123.9m～517.36m，呈现出氨态氮（NH4-N）>硝态氮（NO3-N）>总氮（TN）>有机物（OM）>总磷（TP），变化范围相差4倍左右，表明影响土壤养分的生态过程在不同尺度上起作用，主要影响因素包括养分特性、土地利用以及水塘-沟渠系统景观等。

Spatial Heterogeneity of Soil Nutrients in a multipond-system of Liuchahe watershed

The agriculture nonpoint source pollution is the major influencing factor to lake eutrophication in middle and lower reach of the Changjiang River. An understanding of the distribution of soil nutrients at the field and catchment scale is important for improving agricultural management to control agriculture nonpoint source pollution. Based on spatial analysis function of GIS, spatial heterogeneity of soil nutrients in a multipond-system of Liuchahe watershed was studied using semivariogram of geostatistics. Theoretical semivariogram models of soil organic matter(OM), total N(TN), nitrate(NO3-N), ammoniacal nitrogen(NH4-N) and total P(TP) were spherical model with a sill. The ratio of random variance (nugget) to total variance (sill) was low, these values were 28.8% for TP, 73.2% for TN, 44.0% for NH4-N, 77.35% for NO3-N, 23.9% for OM, respectively. The significant differences in ranges of the five soil nutrients were found. TN had the highest values in the same ranges of 517.36m, TP in range of 472.8m followed them, while NH4-N and NO3-N were the lowest values, 167.6m and 123.9m. These differences in ranges can be explained by particular properties of the soil nutrients, land use patterns and multipond-system landscape..