有机、无机肥料施用后土壤生物量C、N、P的变化及N素转化

CHANGES OF SOIL MICROBIAL BIOMASS C, N AND P AND THE N TRANSFORMATION AFTER APPLICATION OF ORGANIC AND INORGANIC FERTILIZERS

研究结果表明，有机、无机肥施用后，土壤微生物量C、N、P开始增加很快，随着时间的推移，土壤微生物量C又有所降低，但生物量N和P则基本保持稳定。硫铵施入土壤后，微生物对肥料(15)N的生物固持10天后达到最高峰，以后被固持在体内的(15)N有一部分被逐渐释放出来，但一个月后仍有17％左右的(15)N被固持在微生物体内。硫铵与有机肥配合施用时，微生物对硫铵(15)N固持比例有所增加。有机肥中的15N被微生物固持的比例也较大，在肥料施入20天左右达到最大值，一个月后仍有19—25％存在于微生物体内。硫铵施用一个月后(15)N损失高达18％，有机肥中的N也有少量被损失。

Experiments were carried out to study the changes of soil microbial biomass C, Nand P and the transformation of N after application of organic and inorganic fertilizersby using isotope of 15N. The results showed that the soil microbial biomass C, N andP increased greatly after application of organic manures at the beginning of theexperiment and thereafter the biomass C decreased, but the biomass N and Premained constant. The immobilization of 15N rose to the highest about 10 days afterapplication of 15N-labelled (NH4)2SO4 and one month latter about 17% of the 15N wasstill in the soil microbes; when combined with organic manures the immobilization of15N from (NH4)2SO4 increased. About 19-25% of 15N from the 15N-labelled organicmanures .was also immobilized in the microbes at the 30th day after application. Incase (NH)2SO4 was applied alone the loss of N was about 18%, however, whencombined with organic manure the loss decreased.