OBTAINING NPK AND NP(S) FERTILIZERS WITH LONG-RELEASE BY APPLYING AN INORGANIC DIGESTIBLE COATING AND STUDYING THEIR PROPERTIES

A study has been conducted on the possibility of obtaining fertilizers with controlled nitrogen release by applying a non-organic digestible shell of monocalcium phosphate to granules of nitrogen-containing mineral NPK and NP(S) fertilizers. It is shown that the structure of the obtained granules has a clearly defined core and the protective shell itself. The study of granules by fractions showed that the applied monocalcium phosphate shell is evenly distributed over the entire surface of the pellet, regardless of the fraction, and the maximum deviation of the actual shell thickness from the calculated value is less than 10%. The sphericity of the obtained granules is also the same for all fractions, while the coated granules are more spherical compared to the original samples. When studying the physical and mechanical properties of the obtained fertilizers coated with monocalcium phosphate, it was found that they have higher consumer qualities compared to traditional mineral fertilizers – they are characterized by lower caking and dustiness, as well as slightly higher granule strength. A tendency to improve the physical and mechanical properties with an increase in the thickness of the shell for the studied values has been revealed. The study of the rate of nitrogen release in laboratory tests has shown that the use of monocalcium phosphate as a shell material can reduce the rate of release of the element from fertilizers and prolong the period of fertilizer action compared with uncoated samples. Agrochemical tests of the developed coated fertilizers showed an increase in wheat grain yield by 10-18% and a more efficient use of nitrogen from the coated fertilizer compared to the original samples (an increase of 6-18%). Just as for the physical and mechanical properties, it was noted that increasing the shell thickness in the studied range improved the agrochemical efficiency of the fertilizers obtained. In addition, it was found that fertilizers coated with monocalcium phosphate are not inferior in agronomic efficiency to fertilizers with nitrification inhibitors. The study of the dynamics of nitrogen uptake by wheat proved the controllability of nitrogen release from the obtained fertilizers with a shell and the possibility of regulating this process by changing the shell thickness. For citation: Norov A.M., Sokolov V.V., Rybin E.A., Lapushkin V.M., Pagaleshkin D.A., Vladimirov V.A. Obtaining NPK and NP(S) fertilizers with long-release by applying an inorganic digestible coating and studying their properties. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2025. V. 68. N 5. P. 39-48. DOI: 10.6060/ivkkt.20256805.7f.