Physio-chemical preparation of slow-release potassium fertilizers.

In this work, one of the novel types of slow-release fertilizers (SRF) consisting of kaolin as clay material and K2SO4 was synthesized through a mechanochemical process by grinding in a ball mill planetary model. The test samples of different weight % from 25 to 75 of kaolin contents were milled for 2 h at fixed milling speeds about 600 rpm to assess the integration of K2SO4 and to measure the liberation of K+ and SO42- ions into solution. The properties of the studied samples were characterized by Fourier transformation infrared spectrometry (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and ion chromatography (IC). Incorporating K2SO4 into an amorphous kaolin structure using mechanochemistry is a green chemistry method that has been successfully applied. K+ content was measured in deionized water solution and the soil column leaching test was performed to determine the slow-release performance of the material. The optimum released amount of K+ after 24 h was for (1:1 wt ratio) kaolin-K2SO4 samples that were 123.9 ppm at milling conditions 600 rpm milling speed for 2 h, indicating that K2SO4 − kaolin milled samples have good slow-release properties at specific conditions. In addition to being cost-effective and eco-environmentally, with prepared SRF, we can significantly increase the efficiency of fertilizer utilization in green agriculture. [ABSTRACT FROM AUTHOR]