Comparative study of carbamide-based fertilizers with phosphate-containing shells loaded with biochar, diatomite, and saponite components

Trade balances of fertilizers have been studied in this article. The war’s repercussions for the world economy are changes in food, energy, fertilizer prices, and supplies. The production of grain crops in Ukraine and other countries should be increased due to innovative sustainable agriculture technologies that decrease nitrogen granules dissolution. The fertilizers with the controlled release of nutrient elements could increase retention time and improve fertilizer efficiency. This article compared three types of fertilizers with carbamide core and phosphate shell, including various additives (biochar, diatomite, saponite) by morphology end elemental analysis. TEM investigated fertilizer structures in water suspensions to compare their behavior in conditions close to fertilizers dissolution underwater treatment in the soil. The ability to form colloidal micelles was investigated by electrophoreses and compared to find more suitable fertilizer with additives to phosphate shells to slow the release of components and application in agriculture. The surface morphology and internal structure of the granule were investigated by SEM analysis. The elements’ distribution in the shell, interface, and core was investigated by EDX spectroscopy. The existence of colloidal micelles due to fertilizers dissolution is essential for decreasing the solubility of fertilizers. It is shown that adding biochar to granule shell increases shell porosity. The uniform nanoporous structure is observed through all thicknesses of the shell that provide moisture penetration through the shell. The fertilizers' porous shell structure and biochar additives' basic pH can reduce soil acidity and nutrient leaching. The colloidal system of biochar-added sample filtrate could contain nanoparticles with 5–15 nm size. It was concluded that the positively charged colloidal micelles are formed for fertilizer samples with biochar and humates addition. For fertilizers, samples with the addition of diatomite and saponite micelles were not formed.