保护性耕作对土壤微生物量及活性的影响

研究保护性耕作对土壤微生物特性的影响对于土壤管理具有重要意义。试验研究了保护性耕作对麦田土壤微生物量碳、活跃微生物量、土壤呼吸、呼吸商的影响。前3项采用的方法分别是:基质诱导呼吸法、呼吸曲线数学分析法和CO2释放量法。结果表明,保护性耕作土壤微生物量碳0～10cm土层大于10～20cm土层,而常规耕作两土层间无明显差异。秸秆还田在播种前、越冬期和起身期能显著提高土壤微生物量碳,而开花期和收获期则降低土壤微生物量碳。少耕还田10～20cm土层微生物具有较强的养分调控作用。保护性耕作利于0～10cm土层活跃微生物量的提高。秸秆还田和保护性耕作在耕作作业初期(越冬期和起身期)能增强土壤呼吸速率;在耕作作业后期(开花期和收获期)能显著降低土壤呼吸速率。免耕秸秆覆盖在10～20cm土层呼吸商较高,而常规耕作无秸秆还田在0～10cm土层呼吸商较高。土壤微生物量碳和呼吸商是衡量土壤微生物特性的重要指标。

Effects of conservation tillage on soil microbial biomass and activity

Conservation tillage can play an important role in minimizing soil erosion and improving soil quality.The function of soil ecology system is mainly controlled by soil microorganism which is one of the most sensitive indicators.But the main difficulty of the utilization of microbial indicators was the lack of knowledge about the relationships between soil management and characteristics of soil microorganism.Further,the baseline and threshold value for each indicator were still unclear.It is critical for soil management to study the effects of conservation tillage on soil microbial characters.This experiment was carried out at different time after tillage in order to elucidate the effects of conservation tillage on soil microorganism from the aspects of time and space.Six treatments were exposed as conventional tillage with no straw returning(CN),conventional tillage with straw returning(CS),subsoiling tillage with straw returning(PS),harrow tillage with straw returning(HS),rotary tillage with straw returning(RS),no tillage with straw covered(NS).Soil microbial biomass C,active microbial biomass and soil respiration rate were studied with methods of substrate induced respiration,respiration curve mathematics analysis and CO2 emission amount respectively.The results showed that conservation tillage had higher soil microbial biomass C in 0-10 cm soil layer than in 10-20 cm soil layer,while soil microbial biomass C of conventional tillage in both soil layers were almost the same.Straw returning significantly increased soil microbial biomass C at seeding stage,over-wintering stage and erecting stage but reduced soil microbial biomass C at anthesis,harvesting stage.The microorganism in 10-20 cm soil layer of minimum tillage with straw returning could regulate the supply of soil nutrition.Conservation tillage enhanced active microbial biomass in 0-10 cm soil layer.Straw returning and conservation tillage increased soil respiration rate at over-wintering stage and erecting stage but reduced soil respiration rate at anthesis and harvesting stage.NS had higher respiratory quotient(qCO2)in 10-20 cm soil layer and CN had higher qCO2 in 0-10 cm soil layer.Microbial biomass C and soil respiration rate were important indicators of soil microbial characters.But further research is necessary in time effects of tillage treatments on soil respiration rate and microbial characters.