At present, the controlled release principles of slow/controlled release fertilizer mainly include physical, chemical and biological methods. Controlled release methods are mainly divided into envelope method, non-encapsulated method and comprehensive method. The physical method mainly uses physical obstacles to hinder the contact of water-soluble fertilizers with soil water, so as to achieve the purpose of nutrient controlled release. Such fertilizers encapsulate the fertilizer granules with hydrophilic polymers or disperse the soluble active substances in the matrix, thereby limiting the solubility of the fertilizer. That is, the fertilizer is treated to achieve sustained release by a simple microcapsule method and a physical process of the holistic method. The controlled release of fertilizers produced by this method is better, but it often needs to be used together with other methods. The chemical method mainly consists of chemically synthesizing a slowly soluble or poorly soluble fertilizer, and the fertilizer is directly or indirectly bonded to the preformed polymer by covalent or ionic bonding to form a novel polymer. The controlled release of slow/controlled release fertilizer produced by chemical method is better, but the nutrient supply is often insufficient at the initial stage of crop growth, and the cost is relatively high. Biological methods are the use of biological inhibitors (or accelerators) to improve conventional fertilizers. At present, the main target of biological inhibitor application is fast-acting nitrogen fertilizer, which mainly refers to urease inhibitor, nitrification inhibitor and ammonia stabilizer. The biological production process is simple, and the cost is low. The nutrient controlled release effect is unstable when used alone, and the fertilizer effect period is short. And the physical and chemical processing of the fertilizer and the deep application technique of the fertilizer are often required.
The difference between slow release fertilizer and controlled release fertilizer Slow release fertilizer and controlled release fertilizer have slow nutrient release rate and long fertilizer efficiency. In this sense, there is no strict distinction between slow release fertilizer and controlled release fertilizer.
However, from the mechanism and effect of controlling the release rate of nutrients, there is a difference between slow release fertilizer and controlled release fertilizer. Slow release fertilizers slow down the release rate of nutrients in fertilizers by chemical and biological factors, and are affected by many external factors such as soil pH, microbial activity, soil moisture content, soil type and irrigation water volume during release; Fertilizer is a method of coating the water-soluble fertilizer in the membrane to release the nutrients slowly. When the coated fertilizer particles are in contact with the moist soil, the moisture in the soil penetrates into the interior through the envelope, so that some of the fertilizer is dissolved. Part of the water-soluble nutrient is slowly and continuously diffused through the micropores on the envelope. The soil temperature is higher, and the dissolution rate of the fertilizer and the speed across the membrane is faster. The membrane is thinner, and the penetration is faster.
Second, from the perspective of the types of nutrients, the two are also different. Most of the slow release fertilizers are single fertilizers, and the main varieties are slow-acting nitrogen fertilizers, also known as long-acting nitrogen fertilizers. The solubility in water is small. After it is applied to the soil, the fertilizer gradually decomposes under the action of chemical and biological factors, and the nitrogen is slowly released. It can meet the nitrogen demand of the crop throughout its growing season. The controlled release fertilizer is mostly N-P-K compound fertilizer or a total nutrient fertilizer supplemented with trace elements. After being applied to the soil, its release rate is only affected by the soil temperature. However, the effect of soil temperature on plant growth rate is also large. Within a certain temperature range, the soil temperature increases and the release rate of controlled release fertilizer accelerates. At the same time, the growth rate of plants is increasing and the demand for fertilizers is also increasing.
The third is whether the release rate of nutrients is consistent with the demand for nutrients at all stages of the plant. Slow release fertilizers release nutrients unevenly, and nutrient release rates and crop nutrient requirements are not necessarily completely synchronized. The rate at which nutrients are released by controlled release fertilizers is consistent with the rate of plant nutrient demand, thus meeting the nutrient requirements of crops at different stages of growth.
Lianyungang JM Bioscience NBPT Manufacturer supplies a variety of slow/controlled release fertilizers. If you need, please contact us.