基于改进TOPSIS和COK的土壤养分综合评价

Comprehensive evaluation of soil nutrients based on improved TOPSIS and COK

以陕西省周至县北部农耕区为研究对象,选取有机质、碱解氮、速效钾和有效磷4个养分指标,利用主成分分析确定指标权重,将改进TOPSIS技术运用到土壤养分综合评价中,通过计算样点值与最优值、最劣值的距离,以评价对象与最优值的相对接近程度作为评价养分高低的依据,对土壤养分综合指数（Bi）进行COK插值,并绘制土壤养分等级分布图。综合评价结果表明：研究区Bi范围为0.109-0.603,平均值0.285,标准差0.083,变异系数29.12%,属中等变异程度;养分空间分布格局：除南部的马召镇和楼观镇部分区域的养分等级高,由西北角的青花乡、哑柏镇和东部的九峰乡、尚村镇向中部降低的趋势;从高到低的养分等级面积比例为3.47：16.11：29.61：33.12：17.68。研究区土壤养分等级总体偏低,且主要分布在中部地区,与实际情况相吻合,为农耕区土壤肥力改善提供科学依据。该方法相对准确的对土壤养分给予评价,为土壤养分评价提供一条新思路。

Taking farming area in the northern of Zhouzhi County, valuation indexes including organic matter, alkali hydrolysable N, Shaanxi Province as the research object, 4 e- available P and available K were selected to determine the weights of soil nutrients by using principal component analysis. The improved TOPSIS was applied to evaluate soil nutrients. According to the proximity of objects and the optimal evaluation value the nutrients levels were evaluated by calculating the Euclidean distance between the sample value and optimal value as well as that of the worst value. Moreover, the Bi values of soil samples were gotten using the method of Cokriging, and the classification map of soil nutrient zoning was drew. The results showed that the range of Bi was 0. 109 -0. 603, the average was 0.285 ; the standard deviation was 0.083, the variation coefficient was 29.12% and the variation was moderate; the nutrient spatial distribution pattern showed a decrease trend of soil nutrient content from northwest to the middle area. The area ratio of extremely high zone, high zone, medium zone, low zone, and extremely low zone in the study area was 3.47 ： 16.11：29.61：33.12 ： 17.68 ; The levels of the soil nutrients were totally moderate or low, and mainly distributed in the middle area. The evaluation results were consistent with practical situation, so it provided a scientific basis for the improvement of soil fertility.