基于GIS技术的耕地有效磷富集与生态风险评价——以福建省泰宁县为例

Enrichment and Ecological Risk Assessment of Available Phosphorus in Farmland Soils by GIS Technology—— A Case Study of Taining County in Fujian

为了探讨丘陵山地区耕地土壤有效磷的富集特征及其生态风险,利用南方丘陵山地区——福建省泰宁县1982年6069个和2008年2221个样点实测数据建立的1∶5万耕地利用-土壤类型及属性数据库,借助GIS与数学模型集成技术,研究分析了区域耕地不同土壤类型和利用类型有效磷富集状况、生态风险及其空间分异特征。研究结果表明,26年来泰宁县耕地土壤有效磷富集作用明显,有效磷含量平均提高24.32 mg·kg-1,有效磷含量极丰富、丰富等级的耕地面积显著增加,含量中等及以下的面积大幅下降。水稻土土类、潜育水稻土亚类的有效磷富集最明显,紫色土土类、酸性紫色土亚类有效磷富集作用较弱;望天田有效磷富集率最大,菜地有效磷富集率最小。泰宁县存在磷素富集生态风险的耕地面积占全县耕地总面积的31.89%,以中风险区面积最大;水稻土土类、渗育水稻土亚类存在磷素富集生态风险的面积最大。

Assessing enrichment characteristics and ecological risk of available phosphorus in farmland soils is of great significance for rational fertilization and environmental protection. Here a case study was conducted in Taining County, a mountain-hilly region in Northwest Fujian Province, to investigate the enrichment level, ecological risk and spatial distribution of available phosphorus in different types of soil under different land utilizations by using 1∶50 000 land use-soil type database based on the field investigation data at 6069 sampling sites in1982 and 2221 sampling sites in 2008, and by combining geographical information system with mathematic models. Available phosphorus of farmland soils was enriched significantly in Taining from 1982 to 2008, with the average value being increased by 24.32 mg·kg-1and the mean annual growth rate of 0.87 mg·kg-1. In general, the enrichment of available phosphorus in paddy soils was highest, with an average enrichment rate of 1.93, while that in purplish soils was lowest, with an average enrichment rate of 1.14. However, the greatest enrichment rate of available phosphorus was found in rainfed paddy field, with the enrichment rate of 2.08, whereas the lowest enrichment rate in vegetable land, with the enrichment rate of 0.69. The 31.89% of the county′s total farmland soils had the ecological risk of phosphorus. These results indicate the necessity to draw up proper fertilization regime according to the enrichment level and ecological risk of soil available phosphorus in different soil types and different land utilizations.