添加生物质炭对红壤水稻土有机碳矿化和微生物生物量的影响

通过室内培育试验,研究了添加生物质炭对江西红壤水稻土有机碳矿化和微生物生物量碳、氮含量的影响。结果表明:红壤有机碳矿化速率在培育第2天达最大值后迅速降低,培养7天后下降缓慢并趋于平稳;添加生物质炭降低了土壤有机碳的矿化速率和累积矿化量,培养结束时,不加生物质炭的对照处理中有机碳的累积矿化量分别比添加0.5%和1.0%生物质炭的处理高10.0%和10.8%。此外,生物质炭的加入显著提高了土壤微生物生物量,添加0.5%生物质炭处理的土壤微生物生物量碳、氮含量分别比对照高111.5%～250.6%和11.6%～97.6%,添加1.0%生物质炭处理的土壤微生物生物量碳、氮含量分别比对照高58.9%～243.6%和55.9%～110.4%。相同处理中,干旱的水分条件下(40%田间持水量)微生物生物量要高于湿润的水分条件(70%田间持水量)。同时,添加0.5%和1.0%的生物质炭使土壤代谢熵分别降低2.4%和26.8%,微生物商减少了43.7%和31.7%。

Effects of biochar amendments on soil organic carbon mineralization and microbial biomass in red paddy soils

Influences of biochar amendments on soil organic carbon (SOC) mineralization and microbial biomass carbon and nitrogen contents were investigated in red paddy soil collected from Jiangxi Province through two incubation tests. The results showed that the mineralization rate of SOC reached maximum at the 2nd day of incubation and decreased rapidly until the 7th day, then tended to stable afterwards. Throughout the 56 days of incubation, biochar amendments of 0.5% and 1.0% reduced cumulative mineralization of SOC by 10.0% and 10.8% respectively. In addition, applying biochar significantly increased the contents of soil microbial biomass. Compared with the treatments without biochar (CK), microbial biomass carbon and nitrogen contents in soil treated with 0.5% of biochar increased by 111.5% - 250.6% and 11.6% - 97.6%, microbial biomass carbon and nitrogen contents in soil treated with 1.0% of biochar increased by 58.9% - 243.6% and 55.9% - 110.4%, respectively. In the same treatments, microbial biomass contents in drought condition (40% water-holding capacity) were higher than those in wet condition (70% water-holding capacity).The results also indicated that biochar amendments of 0.5% and 1.0% decreased metabolic quotients by 2.4% and 26.8%, microbial quotients by 43.7% and 31.7%, respectively.