Without the right kind of soil, growing plants that can thrive for years is a difficult task. Loam soil is effective because it is composed of clay soil, sand soil and silt soil, each of which has beneficial properties. Loam has some of those beneficial properties, including moisture retention and sufficient drainage capabilities.
Loam is defined as soil that is 40 percent sand, 40 percent silt and 20 percent clay. Only the sand portion of loam soil is visible, with the silt and clay detectable only with the use of a microscope, according to a Plant and Soil Sciences eLibrary lesson. Loam soil has the best balance of those three types of soil and is loaded with nutrients. It is usable as soil for growing a home garden as well as for growing crops on farms.
Unlike sand soil, which has a gritty, sandpaperlike texture, , which has a smooth texture, or , which is sticky and gumlike, loam is the best of all those soils in one package. You can form it into a clump that retains its shape in your hand, but it will crumble if you place a finger within the clump. The sand particles in loam soil are thick and rough, and the silt is coarse but not as abrasive in composition as sand. Clay is the most compacted portion of loam soil. When loam is wet, it becomes sticky and holds its shape well. Dry loam is typically smooth, though any differences in the ratio of sand to silt to clay can affect loam's texture.
Loam soil retains moisture well, making it ideal for plant and flower growth. Because it has a lower concentration of pure clay than clay soil, loam drains well and prevents a garden from becoming overly saturated. Poorly draining soils cannot carry the proper amount of oxygen to plants, which ensures that, at best, the plants experience stunted growth. Loam soil is ideal to grow cabbage (Brassica oleracea var. capitata), brussels sprouts (Brassica oleracea var. gemmifera), peas (Pisum sativum) and leeks (Allium porrum), according to Distance Learning Courses, The Blackford Centre. Those vegetables are grown as annuals.
Some loam soil that is available for sale has a heavier concentration of clay or sand, which can affect plant, flower and vegetable growth. For example, loam soil with a more than 50 percent concentration of clay is problematic because it's difficult to amend with nutrients to improve the soil's efficiency and health. Loam soil that has a more than 50 percent sand content is typically very dry and requires a high level of moisture for proper plant growth.
Prior to beginning work in your garden, ensure its loam soil has the optimal blend of clay, silt and sand by testing it: Wet a clump of loam, and squeeze it into a ribbon. If the clump breaks apart before you form it into a 1-inch-long ribbon and its texture is as coarse as it is smooth, then it's pure loam soil. If the ribbon breaks apart between 1 and 2 inches in length, then the soil is composed primarily of clay.