Nano-potassium intercalated composted coir pith: A slow-release fertilizer suitable for laterite soils of humid tropics of India

High potassium (K)-demanding plantation crops are grown in laterite soils of the humid tropics of India; these soils generally contain low to medium K content. Nano-fertilizers offer an excellent alternative to conventional fertilizers as they release nutrients slowly for a longer period, enhancing their use efficiency. In this study, nano-zeolite based K fertilizer (NZK) was synthesized and intercalated into raw coir pith (CNZK) and composted coir pith (CCNZK). These were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and UV-visible spectroscopy, and the intercalation of NZK was confirmed. The K content in CNZK and CCNZK was estimated to be 27.2% and 31.6%, respectively. Desorption studies indicated that nano-potassium fertilizer alone, and when intercalated into the composted coir pith, was found to release K slowly for a longer period (>480 h) in the laterite soils. Our study suggests that nano-potassium intercalated composted coir pith can be synthesized for slow release of K in the laterite soils of the humid tropics of India.