Types and characteristics of coated fertilizer

There are many types of slow-release/controlled-release fertilizers. For the time being, coated fertilizers are the most popular and popular slow-release/controlled-release fertilizers. The coating materials of coated fertilizers are mostly coated with mineral powder, wax, polymer, sulfur, and polymer resin, and may also be coated with asphalt, Portland cement, ammonium magnesium phosphate, humic acid, and the like. The principle is to coat the surface of the granular water-soluble (fast-acting) fertilizer with a semi-permeable or impervious material, so that the nutrients are slowly released through the micropores and gaps of the capsule, or released in large quantities at a certain growth stage of the crop. Absorbed and utilized, thereby reducing nutrient loss and improving fertilizer utilization.
The earliest coated urea in China The coating materials used in the earliest coated urea in China are mainly zeolite, kaolin, diatomaceous earth, shell powder and so on. A small amount of coated urea, which is also used as a coating for the production of a slow release of bitumen, Portland cement, ammonium magnesium phosphate, humic acid, etc., is generally applied by disc coating or by roller coating. Since the weight of the ore powder is large, the proportion of the coating is generally 1:1, and the content of nitrogen in the urea after coating is about 23%. This product has been replaced by new products for a while.
Sulfur-containing urea-sulfur-coated urea has a special position, mainly because sulfur itself is both a coating material and a nutrient element, and the cost is low. Sulfur-containing urea generally contains 36% to 37% nitrogen. Sulfur-coated urea is suitable for long-term crops such as pasture, sugar cane, pineapple, and rice under intermittent irrigation conditions, and is not suitable for fast-growing crops such as corn. Compared with ordinary urea, sulfur-coated urea can double the effective utilization rate. Sulfur-coated urea is promising as a nitrogen source for rice, and some sulphur-containing urea yields significantly higher yields than urea.
The technology of using fertilizer to make slow-release fertilizer to fertilize fertilizer is produced by a series of manufacturers headed by Zhengzhou University in Henan Province. Calcium magnesium phosphate fertilizer is a kind of glutinous soluble fertilizer, and its dissolution process is slow. It is used as a slow release agent to wrap instant fertilizer to achieve a sustained release effect. According to the formulation requirements of different crops for different nutrients, some nitrogen fertilizers are wrapped, some nitrogen fertilizers are broken into powders, and then encapsulated into granules in proportion with water-insoluble phosphate fertilizers, potassium fertilizers and trace elements. Compound fertilizer. Its advantages are cheaper price and better environmental protection effect. The phosphate fertilizer wrapped with urea is itself a fertilizer, which can provide nutrients for the crops, can be modified on the original compound fertilizer production equipment, and reduces the input cost.
Polymer resin coated urea is coated with urea as a material to form slow/controlled release fertilizer. It is a product of Beijing Academy of Agriculture and Forestry and Shandong Jinzhengda Group. The resin coated urea is a product formed by wrapping urea with various resin materials. The key to resin-coated urea is the uniformity and controllability of the envelope and the stability of the cladding. The biggest advantage of resin-coated urea is that it can achieve the effect of controlled release. The pore size of the coating can be adjusted by selecting different resin materials and their ratios. The proportion of coated urea in the production process by controlling the coating material To adjust the thickness of the envelope, etc., through these processes, the release days of nutrients in the coated urea can be controlled, and the resin having a potency effective period of 60 days, 90 days, 120 days, or even 300 days, 500 days can be produced according to the crop growth cycle. Coated urea.