Abstract: A comprehensive evaluation was made on the effects of applying different organic materials on the soil chemical properties and enzyme activities in Weibei rainfed highland, based on field experiment and laboratory analysis. A total of ten quantitative indices were selected, and factor analysis and minimum Euclidean distance method were employed to evaluate the overall soil fertility. Crop yield was used to verify the evaluation results. Applying organic materials promoted soil fertility and crop yield significantly. Compared with applying chemical fertilizer alone, its combination with straw compost and with organic manure increased the wheat yield by 20.43% and 22.38%, respectively. The soil quality under the combined application of chemical fertilizer with straw compost was the highest, with an integrated score up to 56.53, followed by the combined application of chemical fertilizer with organic manure, and of chemical fertilizer with high amount straw. Therefore, a combined application of chemical fertilizer with straw compost or organic manure could improve the soil fertility significantly, and thereby, increase the crop yield. Using the selected 10 factors and factor analysis to evaluate the quality of soil fertility could accurately reflect the soil fertility level, and predict the soil productivity in the highland.

Key words: building up fertility with organic materials, soil fertility, factor analysis, cluster analysis, grape, light-response curve, fruit quality.