Abstract:

To provide scientific basis for soil quality improvement in typical rocky desertification area in Yanshan and Xichou County, Yunnan Province, the abundance and deficiency of soil fertility was diagnosed and the soil comprehensive fertility was evaluated. First, six soil fertility indexes (pH, organic matter, alkaline decomposition nitrogen, effective phosphorus, fast-acting potassium and electrical conductivity) were measured. Then, the change rule of indexes was analyzed. Finally, the comprehensive score of soil fertility was calculated by principal component analysis. The systematic clustering analysis was used to classify soil fertility scores. The results showed that in the study area, the content of available phosphorus was at medium to low level, and the content of alkali-hydrolyzed nitrogen was at the high level. Principal component analysis was used to extract soil fertility indicators into three principal components, which reflect about 80.52% of all soil information. The first principal component was organic matter and pH, the second principal component was dominated by available potassium, alkali-hydrolyzale nitrogen, and available phosphorus, and third one was electrical conductivity. The soil comprehensive fertility level was divided into two categories, the first category of soil comprehensive fertility was at medium level, and the second category was at lower level. In a word, the soil comprehensive fertility in Yanshan and Xichou County’s typical rocky desertification area was at medium to low level. Soil available phosphorus, organic matter and pH were the key factors affecting the soil comprehensive fertility. So it is necessary to strengthen soil nutrient management and apply fertilizer reasonably to improve the soil fertility level.

Key words: rocky desertification area, principal component analysis, cluster analysis, evaluation of soil fertility