The U.S. Government has been aware of the importance of topsoil for a long time. In 1933, following the agricultural disaster of the Dust Bowl years, a new government agency named “Soil Erosion Service” began its work. Officials might have noticed the misnomer, as the task of the department isn’t to help the topsoil erode more. It’s to prevent erosion, which is the permanent loss of the fertile top layer on the ground. In 1935, the group was more appropriately renamed U.S. Soil Conservation Service, and Natural Resources Conservation Service in 1994.
Soil conservation isn’t in the news often. But the Food & Agriculture Organization of the United Nations (www.fao.org) indicates that 95% of the world’s food supply depends on topsoil. This includes meat. Food animals don’t grow in the soil, but they eat its products.
North Georgia has been dealt a tough hand when it comes to soil quality. No glaciers passed through here during the past four Ice Ages. While they were bulldozing and distributing minerals in places like Iowa and Indiana, making fertile ground for agriculture, Georgia had 2 million years of alternating rain and sunshine. Nutrients and minerals were washed out and left behind a red clay loam of questionable fertility.
Loams are mixtures of three different-sized minerals: Sand, silt and clay. Sand is the coarsest grain size. It absorbs water readily but can’t hold it. The sandy soils of the Georgia Coastal Plain are usable but need irrigation even with all the rain that occurs down there. The larger-grained silt is better for plant growth, and a balanced loam with all three components makes for a good food-producing layer. Our clay loam, though, has a large proportion of clay, the smallest particle size. Field-checking for clay minerals is simple: Squeeze a moist soil sample between your hands. If you can roll it into little sausages, it’s predominantly clay.
Clay minerals stick together, trapping water molecules between them. This is why clay swells so much in wet weather and becomes slippery. But plants have a hard time drawing water out of it. Experienced farmers and gardeners improve their topsoil with large amounts of compost (decaying plant matter). Shredded tree branches and leaves are helpful too. It’s a good idea to forego burning the leaves that accumulated in fall and winter and plowing them into the topsoil instead.
Rudi Kiefer, Ph.D., is a professor at Brenau University, teaching physical and health sciences on Brenau’s Georgia campuses and in China. His column appears Sundays and at gainesvilletimes.com.