According to the current products and types of microbial fertilizers, they can be divided into two categories:
(1) Increase the supply of plant element nutrients through the life activities of the microorganisms contained therein, including the total supply of plant nutrient elements and the effective supply of plant nutrient elements in the soil and production environment, and promote the improvement of plant nutrient status. In turn, the production is increased. The representative variety of this type of microbial fertilizer is rhizobial fertilizer.
(2) Although its products also promote crop yield through the key role of microbial life activities contained therein, the key role of microbial life activities is not limited to improving the nutrient supply level of plants, including the plant growth stimulating hormones they produce. Stimulating effects on plants, promoting the absorption of nutrients by plants, or antagonizing the pathogenic effects of certain pathogenic microorganisms, reducing crop pests and diseases and leading to increased yield. The types and products of such microorganisms are many and complex, but with the further development of research, such microorganisms and their products will have a more reasonable and relatively scientific attribution and classification.