施用有机、无机肥后土壤微生物量、固定态铵的变化及其有效性研究

THE CHANGES OF SOIL MICROBIAL BIOMASS AND THE CLAY FIXED AMMONIUM AFTER APPLICATION OF ORGANIC AND INORGANIC FERTILIZERS AND THEIR BIO-EFFECTS

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 pot experiments were carried out to study the changes of soil microbial biomass C, N and the clay fixed ammonium using the isotope of 15N during winter wheat growth.The results showed that the soil microbial biomass C increased with the application of organic manure at the begainning of the expriment and then gradually decreased with decreasing of the temperature. At the tillering stage when the temperature gradually increased the soil biomass C rised to the highest value at the anthesis stage, being about 554. 9～794.4mg/kg. The application of organic manure resulted in the highest increase in biomass C amonge the treatinents while that of ammonium sulphate treatment giving the lowest. At the harvest time the soil biomass C decreased to the preplanting level. As the soil biomass C the incorporation of orgariic manure increased the amount of biomass N and reached the highest value among the treatments with the check pot being lowest. Unlike the soil biomass C, the amount of soil blomass N was highest at the three leaf stage of wheat, being about 40. 8～79. 0mg/kg and then decreased with growirig of the wheat and at the anthesis stage decreased to the lowest value arid then increased with the maturing of the wheat.