Abstract:

Fertilizers were applied in areas with a 3year plantation of Azadirachta indica in Yuanmou dry hot valley (in Yunnan Province). In this experiment, nine experiments with different combinations of fertilizers and a control were set up in order to study the effect of fertilization on the growth and soil fertility of Azadirachta indica plantation. We analyzed the annual growth of height and DBH, soil nutrient and soil bioindicator. The responses of height and DBH variation to fertilizers were different, and the variance analysis and multiple comparison showed that the growth in heights in single application of nitrogenous fertilizers (treatments 1, 2 and 3) and in mixed application of organic fertilizers and chemical fertilizers (treatments 7, 8 and 9) was remarkably different from that of the control within a 3year plantation. But there was no difference observed in height growth among all treatments within a 1year plantation. It is concluded that scientifically fertilization not only improves soil pH and soil microenvironment, strengthens soil enzyme activities and increases the quantity of soil microorganisms, but also increases the soil fertility, and prevents the degradation of soil fertility. The value of integrated soil fertility index of forest was affected by different treatments of fertilizer application, with the mixed application of nitrogenous fertilizer and phosphate fertilizer being the best for improving the integrated soil fertility index of forest.

Key words: Azadirachta indica, dry hot valley, soil fertility, factor analysis