土壤中的微生物,个体极小,一般用肉眼看不見,需要放在显微镜下才能見到。微生物的种类繁多,生物学特性也是多种多样,因此任何耕地土壤中都有一定的适应类羣,进行各种活动。它們在土壤中的数目很多,每克土壤可多达数十亿个;土壤越肥沃,数目越多;一般在耕作层中的数目多于底土;只有土面因受阳光照射,溫度、湿度变化較大,微生物才較少些,所以微生物在土壤中进行的活动主要集中在耕作层中,在耕 Soil microorganisms, the individual is very small, generally invisible with the naked eye, need to be placed under a microscope to see. There are a great variety of microorganisms and diverse biological characteristics. Therefore, any cultivated land has certain adaptive groups and various activities. They are numerous in soils, with billions of soils per gram of soil; the more fertile the soil, the greater the number; the greater the number of cultivated soils than the latter; and only the surface of the soils affected by sunlight, temperature and humidity Larger, fewer microorganisms, so the activities of microorganisms in the soil mainly concentrated in the tillage layer in the tillage