In agriculture and home gardening, "compost" and "organic fertilizer" are frequently used terms, leading many to mistakenly believe they are completely equivalent. This is not the case. Compost is an important component of organic fertilizer, but the scope of organic fertilizer is much broader than compost. They are related as "part and whole," closely connected yet with clearly defined boundaries.
By definition, compost specifically refers to the loose material formed by the fermentation and maturation of organic waste such as straw, fallen leaves, and kitchen waste under aerobic conditions through microbial decomposition. Its core characteristic is "waste resource utilization," with a low-carbon and environmentally friendly production process. The product is rich in humus and beneficial microorganisms, improving soil structure and fertility. For example, homemade kitchen waste compost on a home balcony and straw compost in farmland are typical compost products. Their production logic is similar to that of simple organic fertilizer production, but the scale and complexity of the process differ significantly.
The definition of organic fertilizer is broader. Any fertilizer made primarily from organic matter, after harmless treatment and fermentation, can be called organic fertilizer. Besides compost, organic fertilizer also includes various types such as fermented livestock and poultry manure, oilseed cake (soybean cake, peanut cake), green manure (purple clover, alfalfa), humic acid fertilizer, and biogas slurry. These fertilizers have a wider range of raw material sources, and the organic fertilizer production process of is more diverse: livestock and poultry manure fertilizer needs to undergo deodorization and sterilization treatment, oilseed cake needs to be crushed and fermented, and green manure requires a special treatment step of turning it back into the field. The process for each type of product is tailored to the characteristics of the raw materials.
The core differences between the two lie in their scope, raw materials, and production processes. Composting is limited to "organic waste" as raw material, and its production relies on natural fermentation or assisted fermentation technology. The product form is mostly loose granules or powder. Organic fertilizer, on the other hand, uses a wide range of organic materials, including animal and plant residues and processing by-products. The production of organic fertilizer places greater emphasis on standardization—some industrially produced organic fertilizers may have appropriate amounts of mineral elements added to adjust nutrients, and the organic fertilizer making process must strictly comply with the national standard for "Organic Fertilizer." From raw material selection to finished product testing, every step must ensure harmlessness and that nutrient indicators meet the standards.
However, their ultimate effects are highly consistent: both provide crops with slowly released nutrients, improve soil structure, reduce reliance on chemical fertilizers, and enhance the quality of agricultural products. In practical applications, compost is often used as a "basic organic fertilizer" for soil improvement, while commercially available organic fertilizers are more suitable for large-scale planting due to their more stable nutrient content and ease of use.
Clarifying the relationship between the two helps growers choose fertilizers more accurately: home gardening can achieve resource recycling by making its own compost, while large-scale planting is better suited to using commercially available organic fertilizers that meet standards, balancing efficiency and effectiveness.
