Relationships Between Soil Labile Organic Matter And Soil Quality Of Reddish Paddy Soil Under Long-term Fertilization

Soil labile organic matter represented the relatively labile and mobile forms of soil organic matter. It had a faster turnover time than total organic matter, and provided the main C source for soil microorganism.A long-term field experiment with the double rice and winter fallow cropping system was conducted based on the Key Field Monitoring Experimental Station for Reddish Paddy Soil Eco-environment in Wangcheng, Ministry of Agriculture, China, to study the relationships between soil labile organic matters and soil quality, provide a theoretical basis for soil quality assessment and sustainable development of agriculture. The results were summed as follows:1. Application of chemical fertilizer could enhance the contents of soil organic matter (SOM) and labile organic matter (LOM), while the both were significantly improved with combined application of organic and inorganic fertilizer. The contents of soil labile organic matters were increased with time during study period. The correlations between soil labile organic matters and soil organic matter were significant. Combined application of organic with inorganic fertilizer was an important measure to improve soil fertility.2. Long-term fertilization could improve soil structure,physical, chemical properties and soil enzymatic activities. However, the effects of single application of chemical fertilizer on the soil structure,physical,chemical properties and soil enzymatic activities were not obvious, while effects of combined application of organic and inorganic fertilizer on the parameters were significant. Long-term combined application of pig manure or rice straw with inorganic fertilizer played an important role for improving soil quality.3. Correlation analysis showed that easily oxidized organic matter and microbial biomass carbon was related or extremely related to the soil quality.In summary, soil labile organic matter could reflect the soil fertility; soil physical and soil chemical properties more accurately and more actually; soil labile organic matter would used as an index to assess the soil quality.