University of Illinois Extension

Don't Treat Your Soil Like Dirt

Dirt is not soil and soil is not dirt, said Greg Stack, U of I Extension horticulture educator.

“There is a definite difference between the two and successful gardeners know the difference,” said Stack. “Soil is a complex community of a lot of 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 is alive and needs to be treated as such. Many first time gardeners often take soil for granted and don’t spend nearly enough time actually building good soil before they start to garden.”

One has to stop and think about what soil does. When asked the question “Soil is home for what?” your response might be weeds, insects, worms, and a lot of other inhabitants. But few people will answer by saying, “soil is home for roots” and this is important if you expect plants in your garden to grow and thrive.

Under every well-grown plant is a healthy root system and a healthy root system starts with well-prepared and well-managed soil. There is no better time than the fall to start looking at your soil and deciding what to do to improve it.

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

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

The task of getting the site ready for a plant is not exactly one of the glamorous jobs in gardening but it is the foundation upon which great gardens, large or small are built. It is also one that may take additional time to achieve because good garden soil is built and not just hauled in from somewhere.

“So, if you are thinking about that fabulous perennial border you want to put in next spring, now is the time to start by getting the soil ready to accept plants next year,” Stack said.

Many plant problems can be traced back to poor soils that have lost, or never had, the ability to support a healthy root system. It could be due to the lack of adequate pore space which provides proper air and water movement; compaction due to traffic or improperly working the soil; inadequate fertility or reduced organic matter content.

“Consider fall as the time to renew some older planting sites or if establishing a new garden getting the soil ready for spring planting,” he said. “Fall is a great time to take soil tests to determine pH and nutrient levels. Doing it now will give you ample time to add needed materials and to adjust these levels in plenty of time 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 or even shred all of those fall leaves that can be added to the soil in preparation for spring planting.”

Think about what makes great soil such a pleasure to work with and why it can grow such great-looking plants. Soil is made up of decomposed minerals, animal and plant waste, microorganisms, air and water.

The particles that make up soil come in all sizes and shapes. These particles have sides that are not uniform and so they don’t fit tight together. They form spaces where air and water move through. These spaces are important to preserve and maintain. The more space that is created the healthier the soil and the healthier the plant is. Gardeners call this soil structure.

“Think about what happens when you move garden tractors, heavy garden equipment, foot traffic or even turning or tilling the soil when it is wet,” Stack said. “The soil becomes compacted, reducing the pore spaces, that reduces air and water movement resulting in poor root growth.

“We have all done this by working wet soil before it has dried sufficiently because we just had to get the garden prepared today. The result is the clods that remain dry will break down eventually, but it may not be until they go through a freeze in the winter.”

So the first rule is to not work wet soils either 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.

Speaking of organic matter, this is the season for it. Fall provides us with an abundance of great material to work with in the form of leaves. 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.

“While all of this sounds pretty easy it really is and about the only thing that many people fail to do is to keep on adding organic matter to the garden and to abide by the rules to maintain good soil structure,” he said.

“Many of us will do all of these things once and think we are now done. Good soil needs to be worked and maintained every year so perhaps resolve now and not on January 1, 2012 to treat your soil like soil and not like dirt.”