[Effects of long-term fertilization on phospholipid fatty acids and enzyme activities in paddy red soil]

Soil samples were collected from the paddy fields at the Ecological Experimental Station of Red Soil, Chinese Academy of Sciences under different treatments of long-term fertilization, and their phospholipid fatty acids (PLFAs) and enzyme activities were determined. The results showed that soil enzyme activities, nutrient contents, microbial biomass, and PLFAs varied greatly with different fertilizations. Fertilization increased the kinds and amount of soil PLFAs. Compared with fertilized soil, unfertilized soil had more fungal PLFAs but less bacterial PLFAs, indicating that fungus was more adaptable to infertile soils than bacteria. Soils applied with NPK and organic fertilizer had higher amount of total PLFAs, which was 3.22 and 1.79 times higher than that under N fertilization and no fertilization. It was indicated that balanced fertilization with NPK or applying organic fertilizer was more beneficial to the growth of plants. Fertilization could also increase soil enzyme activities, and soil urease and phosphatase activities could be used as the indicators of soil fertility.