Loam soil is a soil characterized by roughly equal amounts of clay, silt, and sand. This soil is usually regarded as a gardening ideal, because it promotes the growth of healthy plants. Some soil is naturally loamy, and other soil must be amended to acquire loamy characteristics. Within the large grouping of loam soil, there are a number of lesser soil types such as clay loam and silty loam, differentiated by the precise balance of components in the soil.
Soil can take centuries to build up and reach a point of balance in nature. It includes a wide assortment of materials, and the composition of a soil can determine what can be grown in it. Loamy soil tends to be loose, which is good for plants, and it is also usually rich in nutrients, which means that it requires less fertilizer and nutritional amendments. People can tell if soil is loamy by picking up the soil when it is moist and compressing it; it should break apart into loose chunks. If the soil clings together in a ball, it's clay soil, and if it feels gritty, it's sandy soil.
For people fortunate enough to have loam soil from the start, the soil often requires little care. Working in organic materials can increase the nutritional value of the soil and keep it in good condition, and it is a good idea to protect the topsoil with mulch and cover plants which will prevent topsoil loss. Loam soil drains well, while holding enough water to keep plants happy, provides a steady supply of nutrients, and has a structure which promotes the growth of beneficial microorganisms which will keep the soil healthy.
Gardeners without loam soil will need to embark on a soil amendment program. This can take years to fully come to fruit, and should be thought of as a long term project. Soil improvement starts with soil testing to learn more about the composition of the soil and to determine what needs to be added. Additives can be tilled in, and the soil can be planted. Each year, additional additives may be needed to improve the balance in the soil, until the soil stabilizes with healthy microorganisms which will start to keep the soil healthy.
Loam soil has been highly prized by gardeners for thousands of years. Many of the areas of the world known for having ancient civilizations had, at least at one point, loam soil. However, it is sobering to note that some of these areas were over farmed and poorly managed, and they lost their rich, healthy topsoil. It is important to take care of the soil so that it will continue to be healthy for the life of a garden and for the benefit of future generations.