Have you ever wondered what soil is and if that dirt in your yard is any good for gardening? Although Buncombe County has dozens of soil types, understanding soil basics isn’t that hard. All soils have the same ingredients: minerals, organic materials and the spaces between them, which are filled with air and water. Minerals—mostly weathered rock—make up the bulk of any soil. The smaller amount of organic matter comes from the decay of any living thing, plant or animal! In an ideal soil, half is solids, with equal amounts of air and water filling the space that’s left. This perfect soil provides support for plants’ roots, and the water and nutrients they need to grow.
Of course, it’s unlikely your patch of earth is faultless! The types of rock on a site, the land contours, and climate and biological processes combine to produce soil’s texture, mineral content and acidity (pH). For a plant, these soil characteristics may mean the difference between life and death.
Soil texture is related to the mix of sand, silt and clay particles and affects the ability of the soil to contain air and water. Buncombe County soil types tend to have more clay particles, making them finer-textured, able to hold too much water and susceptible to compacting.
On the plus side, minerals in clay particles are more chemically reactive than those in sand and silt, making them better able to hold nutrients. Buncombe County soils do tend to be acidic (low pH).This makes some of the nutrients, such as phosphorus, unavailable, while releasing others that may be toxic to plants, such as aluminum.
Using plants that prefer the soil you have is an efficient and effective approach to gardening. You can improve your soil by increasing organic matter through mulching and adding lime to raise very low pH to more hospitable levels.
If you want to learn more about soils, a low-cost online course is available from NC Cooperative Extension at:
And 2015 is the International Year of Soils:
Article written by Debbie Green, Extension Master Gardener Volunteer.