Abstract: The soil is a complex system with organic and abio-life-form. The soil-buffer is one of the important properties of the soil. The biodiversity and multifunctional nature of the soil improve the stability and harmony of the ecosystem. The soil biota plays an important role in the soil ecosystem. The author systematically described the function of the soil fauna (earthworms) and microbes in improving the soil nutrient buffer such as improving soil structure and controlling soil nutrients, the behavior in changing the soil physical and chemical properties through bio-sorption, enrichment, precipitation, dissolution and redox, as well as the influence to the bioavailability of heavy metals and the formation of heavy metal toxicity. The purpose is to provide a theoretical rationale for the modern agriculture, especially for organic agricultural.

Key words: soil biota, nutrition, heavy metal, soil buffer ability