The carrier of biological compound fertilizer is a key material that supports and protects microbial cells.

A biological compound fertilizer carrier refers to the solid material used in biological compound fertilizers to carry, adsorb and protect functional microbial cells, and it is an important medium linking microbial inoculants with nutrients. It provides a microenvironment for the cells to inhabit and reproduce, enabling the microbial strains to remain active during production, storage, transport and application, so it is often regarded as one of the key components affecting the quality of biological compound fertilizers.

Common carrier materials include peat, vermiculite, perlite, zeolite powder, diatomite, humic acid substances, as well as thoroughly decomposed organic materials such as straw powder and cake fertilizer powder. These materials can be used alone or mixed in certain proportions to simultaneously meet requirements for adsorption, aeration and nutrient supply.

An ideal carrier usually has good water absorption and water retention capacity and a loose, porous structure, is relatively moderate in pH, does not contain substances clearly harmful to microbial cells, and generally still needs to be sterilized or fully decomposed before use. The carrier not only protects the microbial community, but after being applied to the soil it also helps microorganisms colonize and can improve soil looseness and fertilizer retention capacity to a certain extent.

When applying biological compound fertilizer containing a carrier, try to avoid using it at the same time as strongly bactericidal agents; during storage, pay attention to moisture-proofing, light avoidance and ventilation to prevent the carrier from absorbing moisture and caking, which would affect the activity of the microbial inoculant. Understanding the source and basic properties of the carrier helps in choosing a more suitable biological compound fertilizer product according to soil conditions.