Loam soil is a type of soil that is composed mostly of sand, silt, and a smaller amount of clay. By weight, its mineral composition is about 40–40–20% concentration of sand–silt–clay, respectively. Loam soil is considered ideal for gardening and agricultural uses because it retains nutrients well and retains water while still allowing excess water to drain away. Loam soil provides plants with medium-textured soil, allowing air to circulate plant roots, which protects against diseases often found in poorly draining compacted soils. The soil texture allows roots to spread quickly, retain moisture, and obtain nutrients. Loam soil is suitable for growing most plant varieties.

Loam soil is made up of a balance of the three main types of soil: sand, silt, and clay soil. A simple loam would have a perfect balance of the properties of each particle, however, that does not mean that it is composed of equal parts of each particle. The perfect balance that would make a simple loam would contain 7-27 percent clay, 28-50 percent silt, and less than 52 percent of the balance would be sand. The different types of loam soils each have slightly different characteristics, with some draining liquids more efficiently than others. The soils texture, especially its ability to retain nutrients and water, is crucial.

Creating loose, loamy, fertile soil is not a one-and-done garden task. Turning your soil into loam is an ongoing process by incorporating organic matter every year. Organic matter is quickly depleted as it decomposes, so amend the soil each season, preferably in the fall. The amount of organic matter to add depends on the balance of the soil. Good loam soil can be made using topsoil mixed with organic matter to hold moisture and nutrients. Test the soil for its pH level, nutrients, and organic matter—add lime, fertilizer, and organic matter to reach the ideal needs of your particular plant before seeding or transplanting. Tests ensure you give your plants the environment they need for germination, potting or repotting success, and proper growth.