| To investigate rhizosphere and non-rhizosphere soil fertilities of different crops after harvest of winter rape, including rape, flax, corn and wheat, activities of four soil enzymes (urease, catalase, invertase and phosphatase) and physicochemical indexes were examined. The results showed that there were considerable differences in rhizosphere and non-rhizosphere soil fertilies among the four crops. Rhizosphere soil enzyme activities and the physicochemical indexes were significantly higher than fallow control. Nevertheless, non-rhizosphere were only superor in urease, available N and organic matter contents. Correlation analysis showed that acitivities of soil enzymes had certain corelationships with physicochemical indexes, both of which were important for evaluations of soil fertilities. In addition, rhizosphere and non-rhizosphere soil fertilities of different corps could be divided into three levels by a subjection function method. The fertility levels of different crops were as the follows: wheat rhizosphere soil(F=0.72)＞flax rhizosphere soil (F=0.61)＞rapeseed rhizosphere soil(F=0.56)＞maize non-rhizosphere soil (F=0.44)＞flax non-rhizosphere soil (F=0.39)＞wheat non-rhizosphere soil (F=0.38)＞maize rhizosphere soil (F=0.37)＞rapeseed non-rhizosphere soil (F=0.29)＞fallow CK(F=0.15). It was concluded that it was feasible to evaluate the soil fertility by using subordinate function method with multiple indexes. |