When adding functional ingredients such as slow-release agents, biological agents, and trace elements to BB fertilizer, the BB fertilizer blender requires special adjustments to prevent the additive effects from being lost or unevenly distributed during the blending process.
Biological agents (such as Bacillus subtilis) are sensitive to high temperatures and easily inactivated. Therefore, two key controls must be implemented during blending: first, the blending temperature. By installing a cooling jacket on the BB fertilizer blender barrel, the chamber temperature can be kept below 35°C to prevent frictional heating from the blades, which could reduce the activity of the agent. Second, the mixing order: pre-mix the agent with 10 times the amount of carrier (such as humus powder) to form a “mother powder.” This should then be added after the blender has been running for 5 minutes. This minimizes direct friction between the agent and other ingredients and ensures a viable bacterial count retention rate exceeding 90%.

If adding a slow-release agent, to avoid damaging the coating during mixing, use a “low-shear” impeller (with blunted blade edges), reduce the speed to 15-18 rpm, and control the mixing time to ≤8 minutes. This prevents the slow-release agent particles from excessively colliding and causing the coating to crack, thereby losing its slow-release effect.
For trace elements, they should first be crushed to a size of 100 mesh or larger, pre-diluted with five times the amount of powdered fertilizer (such as monoammonium phosphate powder), and then added to the BB fertilizer blender using a “multi-point feeding” method to ensure even distribution of the trace elements and avoid localized high concentrations that could cause fertilizer damage to the crop.