成都平原西部土壤全磷的剖面分布及主控因素

Profile distribution of soil total phosphorus and controlling factors on the west Chengdu Plain

掌握土壤性质的剖面分布特征是认识土壤元素分布与迁移的重要前提。基于134个土壤剖面的523个采样数据,结合地统计学方法和GIS技术,分析了成都平原西部1m深土壤全磷的剖面分布特征,并揭示了成土母质、土壤类型(亚类和土属)和土地利用方式对土壤全磷剖面分布的影响作用。结果表明,成都平原西部土壤全磷含量较高;0~20cm土壤全磷均值含量为0.89g/kg,显著高于20~40cm(0.59g/kg)、40~60cm(0.48g/kg)和60~100cm(0.48g/kg)土壤全磷均值含量。各层土壤全磷具有一致的空间分布格局,呈现出由东北向西南逐渐降低的空间分布趋势。土壤全磷块金系数在30.65%~68.24%之间,具有中等程度的空间变异性,其空间变异受随机性因素和结构性因素共同影响。不同成土母质、土壤类型及土地利用方式土壤全磷均呈现出表聚趋势。成土母质、亚类、土属和土地利用方式是影响研究区土壤全磷空间变异的重要因素,可分别独立解释其9.6%~32.3%、6.0%~16.9%、8.9%~32.6%和4.2%~6.1%的空间变异。在土壤分类单元中,土属的解释能力大于亚类,可作为探究影响成都平原区土壤全磷剖面分布的基本分类单元。成土母质与土属的解释能力相近,是影响研究区土壤全磷剖面分布的主控因素。

Understanding the profile distribution characteristics of soil properties is essential for studying the distribution and transfer of soil elements. Based on 523 soil samples from 134 soil profiles on the west Chengdu Plain, we analyzed the profile distribution characteristics of soil total phosphorus content（STP） down to 1 m using geostatistics and GIS technology. We revealed the relative contribution of four factors including parent material, soil type（subgroup and soil genus）and land use on the effects of STP distribution in the soil profile. We found that the study area had a high STP content level. Surface STP content was estimated at 0.89 g/kg, significantly larger than that for subsoil which was estimated at 0.59 g/kg in 20-40 cm and 0.48 g/kg under 40 cm,respectively. STP content in each layer had a similar spatial pattern, gradually decreasing from northeast to southwest. The nugget effect of STP in the soil profile was between 30.65%-68.24%,indicating a medium spatial variability affected by structural and random factors. STP content in the study played an accumulative tendency in surface soil under parent material, soil type（subgroup and soil genus） and land use. The explanation ability of parent material, subgroup, soil genus and land use on the effects of STP distribution in the soil profile was 9.6%-32.3%, 6.0%-16.9%, 8.9% -32.6% and 4.2% -6.1%, respectively. For soil classification unit, the explanation ability of soil genus was larger than subgroup, indicating soil genus could be used as the basic classification unit to analyze the effects of soil type on STP on the Chengdu Plain. Parent material was found to have a similar explanation ability with soil genus larger compared to subgroup and land use, meaning both of the two factors were controllers of the effects of STP distribution in the soil profile.