关中地区农田生态系统土壤微生物体氮分异性研究

Study on variation of soil microbial biomass nitrogen of farmland in Guanzhong region

对陕西关中不同地区农田土壤测定结果表明 ,微生物体氮是土壤有机氮库的重要组成部分 ,占土壤全氮的 0 .38%～ 2 0 .55%,平均为 6.80 %。土壤微生物体氮具有显著的分异性 ,表现为不仅具有显著的水平变异性 ,也存在明显的垂直分异性 :随着土层深度增加 ,微生物体氮下降 ,层次间的这种差异十分显著。在耕层 ,土壤微生物体氮与土壤有机质间有密切的正相关关系 ,而在下层它们之间的相关性并不明显 ,这一结果表明 ,耕层土壤有机质是影响土壤微生物体氮的一个主要因子 ;而在耕层以下 。

The experiment results showed that microbial biomass nitrogen of farmland was an important part of soil organic nitrogen, and the ratio of microbial biomass nitrogen to total nitrogen was 0.38%~20.55% with an average of 6.80% in Guanzhong region of Shaanxi. Soil microbial biomass nitrogen has obvious horizontal and vertical variations, with soil depth increase, soil microbial biomass nitrogen decresed, and the significant positive correlation exist between soil microbial biomass nitrogen and soil organic matter, but it isn't obvious in subsoil. This result showed that the soil organic matter is a important factor to affect soil microbial biomass nitrogen in topsiol; but in subsoil, probably exist other factors to affect microbial biomass and they are more obvious than soil organic matter. [WT5HZ]