The term that starts with 'L' and refers to a type of fertile soil consisting of sand, silt, clay, and organic material is "loam". Loam is a type of soil that is ideal for plant growth because it provides a good balance of drainage and moisture retention, as well as a mix of different-sized particles that allow for good aeration and root growth. Loam soil typically consists of about 40% sand, 40% silt, and 20% clay, but the exact proportions can vary. Loam soil is commonly found in areas with a temperate climate and adequate rainfall, and it is often considered the ideal soil type for gardening and farming.