微生物在自然界中的分布,取决于许多综合条件,但其中以养分的有无、温湿度和基质的反应等尤为重要。而所有上述这些条件,在土壤中全都俱备,因而土壤是微生物最好的发育环境。不同的土类,甚至在相同的土类中因栽培技术、作物、施肥等不同其微生物区系无论在量及质上都有着某种程度上的差别。土壤微生物并不是很均匀地分布在整个土体内。但一般来说,在土壤表层深到20— The distribution of microorganisms in nature depends on many comprehensive conditions, but the presence of nutrients, temperature and humidity and matrix reaction is particularly important. All of these conditions, however, are all in the soil, and so the soil is the best developmental environment for the microorganisms. Different soil types, even in the same soil, vary somewhat in quantity and quality due to different cultivation techniques, crops, fertilizations and other micro-fauna. Soil microorganisms are not evenly distributed throughout the soil. But in general, in the soil surface deep to 20-