水稻秸秆不同处理方式对亚热带农田土壤微生物生物量碳、氮及氮素矿化的影响

通过室内模拟培养试验,添加水稻秸秆及由此热解产生的生物质炭,分析亚热带典型旱地土和水稻土微生物生物量碳(MBC)、微生物生物量氮(MBN)及氮素矿化的变化动态,探讨添加不同处理方式的水稻秸秆对土壤碳氮矿化的影响。结果表明,培养35 d后,与对照(CK)相比,添加生物质炭处理,旱地土MBC、MBN、矿化氮量分别增加了34.6%、163.1%和6.4%;水稻土MBC没有明显差异,MBN和矿化氮量分别增加23.0%和15.1%。添加秸秆处理,旱地土MBC、MBN分别增加了90.4%和203.8%,矿化氮量却减少了22.2%;水稻土MBC、MBN、矿化氮量分别增加了13.4%、19.9%和7.3%。研究阐明了生物质炭添加对农田土微生物生物量氮和氮素矿化具有促进作用,而对土微生物生物量碳的影响却因土地利用方式的差异而略有不同;水稻秸秆添加对微生物生物量均有促进作用,其促进程度基本高于生物质炭,而对氮素矿化的影响因土地利用方式的不同而存在差异。

Impacts of rice straw and its biochar product on the amounts of soil microbial biomass carbon and nitrogen and the mineralization of soil organic nitrogen in subtropical croplands

The incubation experiment was conducted to investigate the impacts of rice straw and its biochar product on the amounts of soil microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) and the mineralization of soil organic nitrogen of a typical dryland soil and a paddy soil in subtropical region of China. The results showed that, after 35 days of incubation, the addition of biochar (derived from rice straw) increased MBC, MBN and nitrogen mineralization by 34.6%, 163.1% and 6.4% respectively in the dryland soil and increased MBN and nitrogen mineralization by 23.0% and 15.1% respectively in paddy soil, compared with the no biochar addition treatment. The addition of rice straw increased MBC and MBN by 90.4% and 203.8% respectively, the nitrogen mineralization was decreased by 22.2% in the dryland soil, and increased MBC, MBN and nitrogen mineralization by 13.4%, 19.9% and 7.3% respectively in the paddy soil, compared with the no straw addition treatment. In conclusion, both additions of biochar and rice straw increased microbial biomass in croplands, particularly with the rice straw. The nitrogen mineralization was also increased by the additions of biochar and rice straw, except for in the dryland soil with the rice straw addition. The contribution of rice straw and its biochar product to the dynamics of soil MBC and MBN and the turnover of soil organic nitrogen needs further investigations to clarify, such as by using the isotope techniques.