不同生态系统土壤微生物体氮的差异

Difference of Soil Microbial Biomass Nitrogen Under Different Ecological Systems

分别采取森林、草原、草甸和农田土壤，用熏蒸—淹水培养法测定土壤微生物体氮，并由微生物体碳、氮之比计算微生物体碳，研究不同生态系统土壤微生物体氮、碳的差异及其与土壤有机质间的关系。结果表明，不同生态系统土壤中的微生物体氮存在显著差异：森林土壤（４０３．２μｇ／ｇ）＞草甸土壤（３４０．８μｇ／ｇ）＞草原土壤（３０１．２μｇ／ｇ）＞农田土壤（６２．４～１３７．６μｇ／ｇ），自然植被土壤远高于农田土壤。在任何情况下，上层土壤微生物氮高于下层。土壤微生物体氮与土壤有机质和全氮的变化规律一致。平均土壤微生物体氮是全氮的９．２４％～９．９４％，微生物体碳是有机碳的６．０４％～８．９１％。

Fumigation waterlogged incubation method was used to study the microbial biomass nitrogen or carbon and the relationship between microbial biomass nitrogen and organic matter in soils collected from different ecological systems such as forest, steppe,meadow and arable field. The results reveal that there was a great variation of the microbial biomass nitrogen amounts from forest soils(403.2 μg/g), to meadow soils(340.8μg/g), to steppe soils(301.2μg/g), and to arable soils (62.4￣137.6μg/g), decreasing in the above successive order. However the microbial biomass nitrogen in natural vegetational soils was much higher than that of arable soils. No matter what the condition is, the microbial biomass nitrogen mainly distributed at the 0～20cm depth of a soil, and decreased sharply beneath this layer. The variation of the soil microbial biomass nitrogen was the same as that of soil organic matter and total nitrogen.The percentage of soil microbial biomass nitrogen to total nitrogen ranged from 9.24% to 9.94%,and for microbial biomass carbon to organic carbon, ranged from 6.04% to 8.91%.