Fertile soil is an important component of agriculture and is essential for the growth of crops. It is composed of a variety of materials, including MARL, LOAM, and loess. MARL is a type of sedimentary rock composed of clay and calcium carbonate, which helps to retain moisture in the soil. LOAM is a mixture of sand, silt, and clay, which provides nutrients and aeration for plants. Loess is a type of sedimentary material composed of wind-blown dust and silt, which helps to create a light and porous soil structure. All three of these components are necessary for creating fertile soil that can support healthy plant growth.