Synthesis Optimization and Characterization of Microencapsulated N-P-K Slow-Release Fertilizers

Slow-release microencapsulated N, P, and K fertilizer synthesis was optimized and the products exhaustively characterized. Four NPK formulations with nutrient mass ratios of 1:0:0, 1:1:0, 1:1:1, and 2:1:1 were characterized following European Council Regulation 2003/2003 for fertilizers as well as ICP-AES, 1H-NMR, FT-IR, HPLC, elemental analysis, XPS, SEM, dynamic light scattering, thermogravimetry, differential thermogravimetry, activity index, and leaching rate. These fertilizers have good slow-release properties and decrease waste and crop contaminants, improving environmental protection. Compared to classic granulated fertilizers, plant nutrient availability was improved allowing reduced application. Nutrient leaching parameters describing four different kinetic models were evaluated.