Evaluating Method of Mica Waste Application in Earthworm Cast-Treated Soil for Enhancing Potassium Availability to the Plants with Reference to Tea

Potassium (K) is an essential plant nutrient, and deficiency in the availability of K limits plant growth. Organic amendment in agricultural fields is required to sustain soil health; however, maintaining K availability is a major challenge in organic matter-treated soil. In this context, mica waste, a high potassium-containing mineral, could be an alternative K source for arable soil. In this study, a series of experiments were conducted to evaluate how mica waste could be applied with vermicompost for improving K availability in organic-amended soil. It was observed that vermicomposting of mica waste-amended organic substrates did not increase total K content in the final vermicompost, though earthworms harbour potassium-solubilizing bacteria in their guts. Hence, application of vermicompost, prepared from mica waste-amended organic substrates, did not increase K availability in soil. However, combined application of conventional vermicompost with mica waste was effective to increase K availability in soil, and that was effective to achieve better plant growth and higher K uptake in tea. In this study, combined application of vermicompost and mica waste (at 10% weight of vermicompost) was effective to increase plant growth and K availability in soil.