豆科秸秆、氮肥配施玉米秸秆还田对秸秆矿化和微生物功能多样性的影响

基于施入物料的C/N比,采用室内培养试验,研究了苜蓿秸秆或者氮肥配施玉米秸秆在相同C/N(25∶1)下施入土壤对秸秆矿化和土壤微生物功能多样性的影响。结果表明:相比于玉米秸秆单施和氮肥配施玉米秸秆,苜蓿秸秆配施玉米秸秆提高了CO_2累积释放量,降低了施入有机碳的矿化率,提高了土壤有机碳含量,有利于碳的存储。苜蓿秸秆或者氮肥配施玉米秸秆施入土壤提高了土壤无机氮含量,缓解了对土壤氮素固持作用;苜蓿秸秆配施玉米秸秆相比于氮肥配施玉米秸秆,延长了氮素的可利用性。秸秆施入提高了土壤微生物群落的生理代谢活性,但对微生物功能多样性指数没有显著性影响。氮输入量与土壤无机氮含量显著影响了群落生理代谢活性。

Effects of straw retention with mixing maize straw by alfalfa straw or N fertilizer on carbon and nitrogen mineralization and microbial functional diversity

Based on C/N ratio, an indoor-incubation experiment was used to study the effect of applying maize straw with high quality alfalfa straw or N fertilizer on C and N mineralization and microbial functional diversity under the same C/N ratio(25:1). Four incubation experi-ments were:soil with no addition(CK); soil amended with maize straw(N); soil amended with alfalfa straw and maize straw with an adjust-ed C/N ratio of 25:1(NN); soil amended with inorganic nitrogen fertilizer and maize straw with an adjusted C/N ratio of 25:1(NF). The incubation was conducted at 25 ℃ in the whole experiment duration. The results showed that: compared to treatments of M and MF, MM treatment improved cumulative CO2 emissions, but leaded to a lowest C mineralization rate. MM treatment had the highest of SOC content a-mong the three treatments. Maize straw leaded to a N immobilization during the 270 d of incubation. Combined application of alfalfa and maize straw and combined application mineral N fertilizer alleviate the N immobilization and increase soil mineral N content. Compared to MF treatment, MM treatment prolonged N availability during the incubation. Straw retention improved the community-level metabolic activi-ty, but straw retention had little impact on soil microbial functional diversity. The content of added N and soil mineral N content significantly affected the community-level physiological profile.