What should be considered when storing microbial fertilizer? How should it be stored?

　　During storage, microbial fertilizers should not be kept together with pesticides, chemical fertilizers, or highly acidic or alkaline substances. They also should not be applied simultaneously with large amounts of chemical fertilizers or fertilizers that are either highly acidic or highly alkaline. Soil that is excessively acidic or alkaline, or that is severely dry, can all impair the effectiveness of microbial fertilizers. Next, let’s examine how to store microbial fertilizers and what precautions to take when doing so.

　　What should be kept in mind when storing microbial fertilizer?

　　1. Validity Period

　　At present, few microbial fertilizers in China have an effective microbial survival period exceeding one year; therefore, purchased products should be used promptly, as prolonged storage may disrupt the dormant state of the microbial strains. Some microbial fertilizers, however, can be stored for extended periods, with a shelf life of up to two years under proper conditions.

　　2. Temperature

　　The optimal temperature for applying microbial fertilizers is 25°C to 37°C; application yields are poor below 5°C or above 45°C. Such products should not be applied to crop fields under conditions of high or low temperatures, or during drought. For nitrogen-fixing microbial fertilizers, the ideal soil moisture content is 60% to 70%.

　　3. Location

　　For soils with high sulfur content and paddy fields with rusty water, it is not advisable to apply bio‑fertilizers, as sulfur can kill the beneficial microorganisms. As for paddy fields prone to slurry formation, broadcast application is generally not recommended; foliar spraying tends to be more effective.

　　4. Microbial fertilizers with an insufficient number of viable bacteria cannot be purchased.

　　National regulations stipulate that microbial inoculants must contain at least 200 million viable bacteria per gram (100 million per gram in granular form), while compound microbial fertilizers and bio-organic fertilizers must contain at least 20 million viable bacteria per gram. Failure to meet these standards indicates that the product does not comply with the required quality specifications.

　　5. Period

　　Bio‑microbial fertilizers are not fertilizers per se; applying them 7–10 days before the crop’s critical nutrient‑uptake period and its peak nutrient‑absorption phase yields the best results.

　　6. Attention should be paid to mixing.

　　Do not mix microbial fertilizers with chemical agents, insecticides, herbicides, sulfur‑containing fertilizers (such as potassium sulfate), or rice straw ash, as these products can easily kill the beneficial microorganisms. Alternatively, apply the microbial fertilizer first, wait 48 hours, and then proceed with pesticide or herbicide application. When using it for seed treatment, never combine it with seeds that have already been treated with chemical agents. Additionally, avoid blending it with uncomposted farmyard manure.

　　7. Dosage

　　For fields that have been fertilized with chemical fertilizers for many years, when applying microbial fertilizers, the application rates of both chemical and organic fertilizers should not be drastically reduced. This is because crops have developed a reliance on chemical fertilizers, and they cannot adapt overnight to replacing nitrogen fertilizer with microbial fertilizers. Therefore, the substitution rates should be 30% in the first year, 40% in the second year, and 60% in the third year; phosphate and potash fertilizers should only be supplemented, not reduced.