Office of Research

Don't treat your soil like dirt

Published December 7, 2011

Dirt is not soil and soil is not dirt, said a University of Illinois Extension horticulture educator.

"There is a definite difference between the two, and successful gardeners know the difference," said Greg Stack. "Soil is a complex community of many different particles, microbes, and other living creatures that are put together in such a way as to support good plant growth.

"Dirt, on the other hand, is something you sweep up off the floor and isn't really good for much of anything. For this reason, soil needs to be treated with care. It's alive and needs to be treated as such. Many first-time gardeners take soil for granted and don't spend nearly enough time building good soil before they start to garden." Under every well-grown plant is a healthy root system, and a healthy root system starts with well-prepared and well-managed soil. The fall is a good time to look at your soil and decide how to improve it.

"Many gardeners will point to insects or disease as being the main reason a plant is not growing well," he said. "They are looking for the convenient, quick fix to a problem and not addressing the real issue, which is a poorly prepared planting site.

"Before you spend money on the latest and greatest must-have plant for your garden, think about doing some soil improvement first."

Stack said it's not a glamorous job but it is the foundation upon which great gardens, large or small, are built. He said good garden soil is built, not just hauled in from somewhere.

"Fall is a great time to take soil tests to determine pH and nutrient level," he said. "Doing it now will give you ample time to add needed materials and adjust these levels before you are ready to plant.

"Fall is also a great time to start a compost pile to generate organic matter that can be worked into planting beds. Instead of bagging your leaves, why not run over them with your mower to break them down a bit and then work them into your soil? This will help to add organic matter and help to build the kind of soil structure that any plant would love to grow in."

Stack said soil is made up of decomposed minerals, animal and plant waste, microorganisms, air and water. The particles come in all sizes and shapes. These particles have sides that are not uniform so they don't fit tightly together. They form spaces where air and water move through. These spaces are very important to preserve and maintain. The more space that is created, the healthier the soil will be and the healthier the plant it can support. Gardeners call this soil structure.

Compacted soil reduces the pore spaces, which reduces air and water movement and results in poor root growth.

Stack recommends that you not work wet soils in the fall or spring. "Wait until they dry to a crumbly texture before tilling or digging in those fall leaves or compost," he added.