基于改进TOPSIS模型的土壤养分综合评价

Comprehensive Evaluation of Soil Nutrients Based on Improved TOPSIS Model

在山西省高平市共采集2 583份土壤样本,测定了土壤有机质、全氮、有效磷、速效钾4项评价指标,用熵权法确定指标权重,将改进后的TOPSIS模型运用到土壤养分综合评价中,旨在客观评价高平市土壤养分状况,为因地制宜地测土施肥提供参考。结果表明,高平市土壤速效钾含量丰富,有机质、全氮、有效磷含量为中等水平;半变异函数模型拟合结果显示,各指标最优模型均为指数模型,其块基比均在50%左右,具有中等程度的空间相关性,受内部因素和外部因素共同影响,其中,全氮的变程最大,空间相关性较强,主要受较大尺度因子的影响;各养分指标空间分布均表现出一定程度的二阶趋势效应,其中,土壤有机质含量整体呈现东高西低的趋势,全氮含量自中间向四周辐射降低,有效磷含量西部地区较东部相对高一些,而速效钾含量则为东南部较西北部含量明显丰富;区域土壤养分综合评价显示,高平市土壤养分综合指数为0.332~0.598。总体来说,高平市土壤养分属于中等水平,还有很大的提升空间,改进TOPSIS模型可为客观评价研究区土壤质量水平提供方法借鉴。

A total of 2583 soil samples were collected in Gaoping city,Shanxi province,and four evaluation indexes(soil organic matter(SOM),total nitrogen(TN),available phosphorus(AP)and available potassium(AK))were determined to objectively evaluate the soil nutrients status of Gaoping city,and provide a reference for soil-testing and fertilization according to local conditions.The index weight was determined by entropy weight method,and the improved TOPSIS model was applied to comprehensively evaluate the level of soil nutrients.The results showed that the area in Gaoping city had rich content of AK,mediun SOM,TN and AK.The fitting results of the semivariogram model showed that the optimal model of each index was exponential model,and its nugget coefficient was about 50%.It had a moderate degree of spatial correlation and was affected by both internal and external factors.TN had the largest range and strong spatial correlation,which was mainly affected by larger scale factors.The spatial distribution of each nutrient index showed a certain degree of second-order trend effect,in which the content of SOM showed a trend of higher in the east and lower in the west,the TN content reduced from the middle to the surroundings,the content of AP was relatively higher in the west than in the east,while the content of AK was obviously richer in the southeast than in the northwest.The map of the comprehensive evaluation of soil nutrients in the study area showed that the variation range of the soil nutrient comprehensive index in Gaoping city was 0.332-0.598.In conclusion,the soil nutrient level in Gaoping city was at a medium level,and there was still much room for improvement.Improved TOPSIS model could provide a method for the objective evaluation of the soil quality at a regional scale.