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利用15N示踪技术和盆栽试验研究了施用有机、无机肥料后，土壤微生物量C、N和土壤固定态铵的变化及其生物有效性。结果表明:土壤微生物量C在小麦三叶期时较高，之后随着外界温度的下降，生物量C逐渐下降;小麦返青后又上升，至开花前后达到最高值，为554.9～794.4mg／kg。并以施用稻草和猪粪处理的最高，单施硫铵的最低，以后逐渐降低直至收获。土壤微生物量N的变化与C的变化不太一致，土壤微生物量N在小麦三叶期最高，为40.8～79.0mg／kg，并以施猪粪和稻草处理的最高，对照处理中最低;随着小麦的生长逐渐下降，到小麦开花前后下降到最低点，但至成熟时又有所上升。土壤固定态铵的变化趋势与土壤微生物N的变化趋势相似。施肥后被固定在微生物体内和粘土矿物中的N，在小麦生长期间有很大部分仍能被小麦吸收利用。被固定在微生物体内的硫铵N、稻草N和猪粪N的最大释放率分别为64.7％～84.3％、60.4％～77.1％、59.3％～685％;被固定在粘土矿物中硫铵N的最大释放率为59.5％～76.2％。
The 15N tracing technique and pot experiment were used to study the changes of microbial biomass C, N and soil fixed ammonium after the application of organic and inorganic fertilizers and their bioavailability. The results showed that soil microbial biomass C was higher at the three-leaf stage of wheat, and then decreased with the decrease of outside temperature. After returning to green, the soil microbial biomass C increased again and reached the highest value before and after flowering, which was 554.9-794.4mg / kg . And the highest application of straw and pig manure, the lowest ammonium sulfate alone, and then gradually reduced until harvest. The change of soil microbial biomass N was not consistent with the change of C, and the soil microbial biomass N was the highest in the three-leaf stage of wheat at 40.8-79.0 mg / kg, and was the highest in the treatment of pig manure and straw with the lowest in the control treatment. The growth of wheat declined gradually until it reached the lowest point before and after the flowering of wheat, but it increased again when it matured. The trend of soil fixed ammonium was similar to that of soil microbial N. After fertilization, N immobilized in the microorganisms and in the clay minerals can be largely absorbed and utilized by wheat during wheat growth. The maximum release rates of ammonium sulfate N, straw N and pig manure N immobilized in the microorganisms are respectively 64.7% -84.3%, 60.4% -77.1%, 59.3% -685% The maximum release rate was 59.5% ~ 76.2%.