Loam soil is considered the best because it combines the benefits of the multiple types of soil that make it up. Loam contains 40 percent sand, 40 percent silt and 20 percent clay. The soil's particles pack together well. Loam soils make growing plants in your garden or in pots relatively easy. However, you still should add organic matter to loam soil if you cultivate it every year.
Sand has large particles and offers good aeration. The sand allows loamy soil to drain well so that enough air can reach a plant's roots, even after a spring thaw or heavy rain. Sand keeps loam soil from being compacted, which is important because compacted soil reduces air circulation to the root zone and thus allows rainfall or irrigation to run off, which boosts instances of erosion. Also, the sand part of loam soil makes loam quicker to warm up for spring planting.
Clay particles are very fine and hold water and nutrients well, which sand does not do. Clay keeps loam soil from being too dry, so you do not have to water and fertilize the soil as often as required when planting with sandy soil. In addition, even when vegetation that covers the loam soil is lacking, the soil is not subject to wind erosion because clay is heavier than another type of soil found in loam -- silt -- and actually is sticky when wet.
Silt particles feature qualities that fall between those of clay and sand. Silt feels smooth and powdery and is one of the most fertile types of soil. Like clay, it holds nutrients and water better than sand does. It additionally features not only minerals such as quarts but also organic matter, which helps with plant growth. Silt soils do not clump easily and have a slightly slippery texture. These types of soils actually are rare, especially in gardens.
Texture and Yield
Loam soil is medium-textured with grains you can see and feel easily. Loam tends to be soft and friable and does not become hard in dry weather. Because loam is easier to work with, it is better suited for a wide variety of crops. Practically all farm crops -- which include corn, potatoes, small fruits, cereals, grasses and alfalfa -- grow efficiently on loam. In addition, loam produces higher yields more economically than other soil types can. Most plants grow the best in loamy soil.