This document discusses soil fertility and soil depletion. It defines soil fertility as the capability of soil to supply adequate nutrients to plants. The key factors that determine soil fertility are soil organic matter, texture, depth, nutrient content, storage capacity, and pH. There are three types of fertile soil: compost soil, no-till soil, and cover-crop soil. Soil depletion occurs when the components that contribute to fertility are removed and not replaced. The main causes of soil depletion in Bangladesh are rapid organic matter degradation, intensive cropping, unbalanced fertilizer use, and soil erosion by wind and water.