Is there a difference between “microbial fertilizer” and “microbial inoculant”?

　　Microbial fertilizers are products containing live, specific microorganisms that are applied in agricultural production. Through the metabolic activities of these microorganisms, they increase the availability of plant nutrients, promote plant growth, boost yields, and enhance the quality of agricultural products as well as the agroecological environment. Microbial fertilizers encompass microbial inoculants (agricultural microbial agents), compound microbial fertilizers, and bio‑organic fertilizers.

　　1. Agricultural microbial inoculants: These are live‑microbe formulations produced through industrial-scale propagation and processing, containing target microorganisms (effective strains). They can directly or indirectly improve soil quality, restore soil fertility, maintain the balance of rhizosphere microbial communities, and degrade toxic or harmful substances. When applied in agricultural production, the metabolic activities of the microorganisms they contain increase the availability of plant nutrients, promote plant growth, enhance the quality of agricultural products, and improve the agro‑ecological environment.

　　2. Compound microbial fertilizer: A live‑microbe product obtained by combining industrially propagated microorganisms with nutrient substances.

　　3. Bio-organic fertilizer: A type of fertilizer that combines specific functional microorganisms with organic materials derived primarily from animal and plant residues—such as livestock and poultry manure and crop straw—and subjected to harmless treatment and decomposition, thereby exhibiting both microbial fertilizer and organic fertilizer effects.

　　The difference between microbial inoculants and microbial fertilizers:

　　Microbial inoculants, often abbreviated as “agricultural microbial agents,” are governed by the standard “Agricultural Microbial Inoculants” (i.e., microbial inoculants). These are live‑microorganism products formed by directly applying one or more target microorganisms that have been industrially propagated and multiplied, or by adsorbing them onto a carrier that supports their survival. They constitute one category within the broader class of microbial fertilizers.

　　“Fungal fertilizer” is a shorthand term used by the general public and some distributors to refer to microbial fertilizers—products that consist of live microbial strains, compounded with nutrients and other ingredients after industrial-scale propagation. These products are applied at relatively high rates per unit area and currently fall into three categories: compound microbial fertilizers, bio‑organic fertilizers, and agricultural microbial inoculants, the latter encompassing microbial agents.

　　Fertilizer‑based microbial products are typically packaged in larger sizes, most commonly 40 kg, with 25 kg and 50 kg options also available. They generally require relatively high application rates per mu. Given that the organic matter content across China currently hovers around 1.0% per mu, fruit trees usually demand about 200–500 kg per mu. At present, market prices for these bulk microbial fertilizers tend to cluster between 2,000 and 3,000 yuan per ton, and they are gradually becoming the mainstream choice in the fertilizer market. For compound microbial fertilizers and bio‑organic fertilizers, the recommended application rate exceeds 200 kg per mu, whereas agricultural microbial inoculants are applied at much lower rates—typically 2–5 kg per mu. To distinguish them, agricultural microbial inoculants are often referred to simply as “inoculants” and are classified as minor fertilizers or formulated products, while compound microbial fertilizers and bio‑organic fertilizers are collectively called “microbial fertilizers” and are considered major fertilizers.

　　The Relationship Between Microbial Inoculants and Microbial Fertilizers

　　In the development of national standards, microbial inoculants are classified as a type of microbial fertilizer. Among the 152 microbial strains currently registered for use in such products, the top ten most frequently employed strains are: Bacillus subtilis, Bacillus mucilaginosus, Bacillus licheniformis, Bacillus megaterium, Bacillus amyloliquefaciens, Saccharomyces cerevisiae, Bacillus pumilus, Streptomyces coelicolor, Lactobacillus plantarum, and Aspergillus niger, with Bacillus species accounting for 75% of the total.

　　Currently, microbial inoculants on the market are classified according to the types of microorganisms they contain or their functional characteristics into: rhizobium inoculants, nitrogen-fixing bacterial inoculants, phosphate-solubilizing microbial inoculants, silicate‑solubilizing microbial inoculants, photosynthetic bacterial inoculants, organic‑matter decomposition agents, plant‑growth‑promoting microbial inoculants, mycorrhizal fungal inoculants, and bioremediation microbial inoculants. The formulations are predominantly liquid, though powder and granular forms are also available.

　　Depending on the region and the crop, microbial inoculants are generally applied in four ways:

　　1. Apply 2 kg per mu as a base fertilizer, spreading it evenly during plowing.

　　2. Apply as a topdressing at a rate of 1–2 kg per mu.

　　3. For drip irrigation and flush application, use the clear liquid in combination with conventional fertilizers for watering, and apply the residue as a base fertilizer to improve soil quality.

　　4. Use as a seed fertilizer: mix an appropriate amount with the seeds and apply using standard seedling-raising or sowing methods.