Described herein is a mineral-releasing compost prepared by combining a prebiotic material, a probiotic material, and one or more mineral gluconate salts to form a composting mixture, controlling composting conditions to allow for the composting mixture to decompose, and allowing the composting mixture to fully stabilize and mature, wherein the compost includes one or more minerals as digested products of the respective mineral gluconate salts. The mineral-releasing compost is particularly suitable for remediation of soil contaminated with heavy metals and for amendment of soil deficient of certain minerals.