有机-无机配施对农田土壤微生物量碳氮的影响研究

Long-term Application of Chemical Fertilizer and Organic Matter Improved Soil Microbial Biomass Carbon and Nitrogen in Fluo-aquic Soil

通过分析潮土21年不同施肥措施下夏玉米各生育期土壤微生物量碳（SMBC）、微生物量氮（SMBN）、微生物量碳氮比（SMBC／SMBN）、微生物量碳与总有机碳的比值（SMBC／TOC）及微生物量氮与全氮的比值（SMBN／TN），阐明土壤微生物量碳氮对不同施肥的响应特征。选取7个施肥处理：不施肥（CK）、单施氮肥（N）、氮磷钾平衡配施（NPK）、施氮磷钾肥＋有机肥（NPKM）、施氮磷钾肥＋玉米秸秆（NPKS）。在夏玉米苗期、抽雄、灌浆、成熟4个生育期采集耕层（0—20cm）土壤．采用氯仿薰蒸法测定土壤微生物量碳氮。NPKM和NPKS处理均能显著提高玉米各生育期土壤微生物量碳氮，且以NPKM效果更佳。NPKM处理土壤微生物量碳在苗期、抽雄期、灌浆期、成熟期分别比CK处理提高36．6％、91．7％、167．5％和100．6％：土壤微生物量氮在苗期、抽雄期、灌浆期、成熟期分别提高2．0、4．6、3．6和2．5倍。不同生育期，同-施肥处理中土壤微生物量碳氮均随生育期推进总体呈升高趋势。与CK相比，施肥显著降低土壤微生物量碳氮比；同时提高微生物量碳与总有机碳的比值（SMBCfFOC）及微生物量氮与全氮的比值（SMBN／TN），且以NKPM提高的幅度最大，增幅分别为25-3％和147．0％，有机-无机配合施用显著提高夏玉米不同生育期耕层土壤微生物量碳和微生物量氮，且以化肥配施有机肥的效果更佳。有机-无机配施降低土壤微生物量碳氮比，提高土壤微生物量碳与有机碳的比值及土壤微生物量氮与全氮的比值，从而促进土壤微生物对碳氪的固持，提高土壤碳氮肥力。

In order to investigate the effects of various fertilization treatments on soil microbial biomass carbon （SMBC） and soil microbial biomass nitrogen （SMBN）, the paper analyzed SMBC, SMBN, the ratio of SMBC/SMBN, and the percentage of microbial biomass C in total organic C （SMBC/TOC） and microbial biomass N in total N （SMBN/TN） at different growth stages of maize after 21- year of continuous fertilization management in the fluo-aquic soil. Seven fertilization treatments were selected, including CK （no fertilizer）, N （chemical nitrogen）, NP （chemical nitrogen and phosphorus）, NK （chemical nitrogen and potassium）, NPK （chemical nitrogen, phosphorus and potassium）, NPKM （NPK plus organic manure） and NPKS （NPK plus maize stalk）. The topsoil （0--20 cm） was collected at the stage of seedling, elongation, grain-filling and maturing of summer maize. SMBC and SMBN were determined by CHC13 fumigation method. Both NPKM and NPKS significantly improved SMBC and SMBN, while the effect of the former one was better. Compared with CK, SMBC in the treatment of NPKS was increased by 36.6% ,91.7%. 167.5%, 100.6% at the seedling, elongation, grainfilling and maturing stages representatively, and SMBN was increased by 2.0, 4.6, 3.6, 2.5 times in the corresponding stages. In the entire growth season, SM BC and SMBN with different treatments increased with the growth of summer-maize. Compared with CK, the ratio of SMBC/SMBN was significantly lower, and the percentage of SMBC/TOC and SMBN/TN was significantly higher in other treatments. The maximum increase of SMBC/TOC and SMBN/TN was found in NPKM, and it increased by 25.3% and 147.0% higher than CK. The application of chemical fertilizer combined with organic matter could increase SMBC and SMBN in the topsoil of fluo-aquic soil at different growth stages of summer-maize, and the application of chemical fertilizer combined with manure is a better method. The application of chemical fertilizer combined with organic matter decreased the ratio of SMBC/SMBN and increased the percentage of SMBC/TOC and SMBN/TN. It is suggested that the application of chemical fertilizer combined with organic matter could promote the retention of soil carbon and nitrogen by microorganisms and also could improve the fertility of soil carbon and nitrogen.