长期施肥对红壤有机碳矿化及微生物活性的影响?

为评价不同施肥条件下红壤有机碳矿化和微生物活性及两者之间的关系，对长期定位试验施有机肥（M）、施用氮、磷、钾化肥（NPK）、有机肥配合化肥（NPKM）、秸秆配合化肥（NPKS）和不施肥（CK）共5个处理的红壤进行室内培养，分析不同施肥处理下红壤有机碳矿化的CO2释放量﹑微生物数量及微生物碳源代谢特征。结果表明，不同施肥处理的土壤有机碳矿化释放CO2量差异显著，由一级反应动力学方程拟合计算出土壤潜在有机碳矿化释放CO2–C量的大小顺序：M > NPKM > NPK ≈NPKS > CK，其值分别为180.3﹑88.5﹑47.6﹑43.4和34.5 mg/kg 。培养初期微生物活性较弱时CO2的释放速率最高，微生物数量的增长落后于有机碳矿化速率变化，但培养14﹑35和69 d 时3种微生物数量大小顺序为M > NPKM > NPK≈NPKS≈ CK，处理间差异显著且与CO2释放量显著相关。不同施肥处理间微生物群落结构差异显著，其趋势与有机碳矿化相符合。说明长期施肥特别是长期施用有机肥能影响微生物的群落结构，提高红壤微生物活性，进而促进微生物对有机碳的矿化。

Effects of Long-Term Fertilization on Mineralization of Organic Carbon and Microbial Activity in Red Soil

To investigate mineralization of organic carbon and microbial activity and their relationship under different fertilization in red soil, five kinds of samples from long-term fertilized soil (manure, M; nitrogen plus phosphorus plus Potassium, NPK; manure plus NPK, NPKM; NPK plus straw, NPKS; without any fertilization, CK) were incubated, and the CO2 production rate, the number of and metabolic diversity of microbes of samples were evaluated. The result shows that: soil CO2 production amoung samples is significantly different, the order of potential CO2-C production of five samples, which derived from the first-order kinetic model, is as follows: M(180.3 mg/kg) > NPKM(88.5 mg/kg ) > NPK(47.6 mg/kg) ≈NPKS(43.4 mg/kg )> CK (34.5 mg/kg ). The increasing number of bacteria, fungi and Actinomycete which is later than their mineralization rate of organic carbon, however, is significantly different between the samples under different fertilization at the 14th,35th,69th day of incubation. Their following pattern: M > NPKM > NPK≈NPKS≈ CK, is significantly correlatived with those of CO2 production. The microbial communities of the samples under different fertilizations are obviously different, which is similar to their mineralization of organic carbon. The result shows that long-term fertilization, especially the use of manure, has significant effect on microbial communities, enhances activity of microbe, and then increases the microbial mineralization of organic carbon.