温度与微生物制剂对小麦秸秆腐解及土壤碳氮的影响

【目的】探讨不同温度和添加微生物制剂条件下，小麦秸秆腐解对土壤中不同形态碳、氮含量的影响，为评价秸秆还田措施补充土壤养分、改善土壤肥力的贡献提供理论依据。【方法】采用室内模拟恒温培养方法，于15和20 ℃条件下，在装有127.5 g风干土样的培养盆中，分别添加不同量秸秆（0.961，0 g/盆）和微生物制剂（2.88，0.961，0 mg/盆），后培养75 d，测定秸秆腐解期间CO₂释放量及腐解后土壤中不同形态碳、氮的含量。【结果】温度对秸秆腐解和养分释放影响较大，而微生物制剂未表现出作用效果。经75 d腐解培养后，添加秸秆与对照相比，15 ℃下秸秆CO₂-C的净累积释放量较20 ℃下低37.1%，而土壤有机碳和微生物量碳净增量分别增加了260%和949%；同时，15 ℃下土壤全氮和铵态氮含量分别较20 ℃下降低了100%和18.4%，微生物量氮提高了262%。【结论】较低的温度有利于秸秆对土壤有机碳和微生物量碳、氮的截留和保蓄，而较高的温度会加速秸秆有机碳向无机碳转化，同时微生物制剂在本研究的水热条件下未能发挥作用。

Effect of temperature and microbial agent on wheat straw decomposition and soil carbon or nitrogen

【Objective】In order to offer some theoretic foundation for the evaluation of straw returning measures to supply the soil nutrients and improve soil fertility,the decomposition of wheat straw was incubated to investigate the effect of temperature and microbial agent on wheat straw decomposition and soil carbon or nitrogen.【Method】The soil(127.5 g air dried soil) with(0.961 g/pot) and without wheat straw was incubated at constant temperature(15 ℃,20 ℃) and microbial agents(2.88,0.961,0 mg/pot) for 75 d.The CO2 production during the incubation and different forms of soil carbon and nitrogen content after incubation were determined.【Result】There was a strong influence of temperature on the decomposition of straw and nutrient release,however,microbial agents had no obvious effect.Compared to control at the end of 75 day incubation the net cumulative CO2-C evolution at 15 ℃ under straw addition was 37.1% lower than that of 20 ℃,while the net increase amounts of soil organic carbon and microbial biomass carbon were 260%,949%,respectively.At the same time,the content of soil total nitrogen and ammonium nitrogen was decreased by 100% and 18.4% in 15 ℃ treatment compared to 20 ℃ treatment,and the microbial biomass nitrogen was increased by 262%,respectively.【Conclusion】Lower temperature is favorable for soil organic carbon,microbial biomass carbon and nitrogen sequestration and retention,however,higher temperature makes it easier to transform the organic carbon of straw into inorganic carbon,in addition,microbial agents have little effect under this controlled conditions.