The differences between controlled release fertilizer and slowly-release fertilizers

The micro-fertilizers of zinc sulfate monohydrate and manganese sulphate monohydrate we produced have granular with size 2-4mm. However, do you know this kind of fertilizers belongs to controlled release fertilizer or slowly-release fertilizer? According to the Industry Standards of “controlled release fertilizer” formally carried on this July 1, there are three differences between the two.

First, the nutrient release degree is the main difference between controlled-release and slowly release fertilizer. Controlled release fertilizer release the nutrition at the same step of crops growth while slowly-release fertilizers release the nutrient as time goes.

Second, the core index of controlled release fertilizer is more strict than slowly-release fertilizers. For Controlled release fertilizer, nutrient release rate in 25 ℃ immersion water for 24 hours is less 12%; Accumulative nutrient release rate for 28 days is less 75%; the accumulation quartile release rate in marked nutrient release period is less 80%. And the requirements of slowly- release fertilizer: nutrient release rate in 15 ℃ immersion water for 24 hours is less 12%; Accumulative nutrient release rate for 28 days is less 80%; the accumulation quartile release rate in marked nutrient release period is more than 80%.

Third, the packaging labeling requirements of controlled-release fertilizer is more comprehensive than slowly-release fertilizers. Controlled release fertilizer package not only requires to be marked with total nutrient content, the match type, nutrient release period and the accumulation nutrient release rate of the seventh day and the 28th day, but also should be marked the nutrient release period in the northern region for crops under 15 ℃ in winter.

According to the latest on the introduction of the standard to define, granular zinc sulfate or acid manganese belong to common kind of controlled-release fertilizers.