Abstract:

【Objective】 A non-linear assessment model was used to quantify the changes of paddy soils with different productivities and provide a scientific basis for sustainable use of paddy soil in double-rice growing area. 【Method】 This study was conducted in important double-rice producing areas. A comprehensive method for evaluating soil quality was adopted. Soil quality was evaluated according to four major soil functions, i. e., resistance to physical degradation, nutrient supply and storage, resistance to biochemical degradation and conservation of crop productivity. Every soil function and individual soil indicator was weighted on the basis of the expert opinion panel and statistical tools such as factor analysis,then soil property values measured under different productive paddy soil were transformed into unitless scores (between 0 and 1) using non-linear score equation. The non-linear assessment model based on soil function could comprehensively evaluate the soil quality, which can be directly reflected by this method. 【Result】 Results showed that high yield paddy soils in eight experimental areas have physical, chemical and biochemical qualities. The middle yield paddy soil has good physical and biochemical qualities, but poor chemical qualities. The physical, chemical and biochemical qualities in low yield paddy soils were all poor, which mainly reflected low organic matter, nutrient supply and storage ability. 【Conclusion】 Overall soil quality of high yield paddy soil was good, which did not create obstacles to double rice growth. The main factor affecting middle yield paddy soil was unbalance of soil nutrient supply in the soil. The overall soil quality of low yield paddy soil was poor, input of increasing organic matter and inorganic nutrient is required for improvement of the overall soil quality in this type of paddy soil.

Key words: double rice cropping area, paddy soil, soil quality indicators, soil quality assessment