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

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¹⁵N的生物固持10天后达到最高峰,以后被固持在体内的¹⁵N有一部分被逐渐释放出来,但一个月后仍有17%左右的¹⁵N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¹⁵N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¹⁵N损失高达18%,有机肥中的N也有少量被损失。

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

Experiments were carried out to study the changes of soil microbial biomass C, N and P and the transformation of N after application of organic and inorganic fertilizers by using isotope of ¹⁵N. The results showed that the soil microbial biomass C, N and P increased greatly after application of organic manures at the beginning of the experiment, and thereafter the biomass C decreased, but the biomass N and P remained constant. The immobilization of ¹⁵N rose to the highest about 10 days after application of ¹⁵N-labelled (NH)₂SO₄ and one month latter about 17% of the ¹⁵N was still in the soil microbes; when combined with organic manures the immobilization of ¹⁵N from (NH;), SOS increased. About 19-25% of ¹⁵N from the ¹⁵N-labelled organic manures was also immobilized in the microbes at the 30th day after application. In case (NH)₂SO₄ was applied alone the loss of N was about 18%, however, when combined with organic manure the loss decreased.