How to Fix Sorry Soils

Do you have bare spots in your yard? You might call these areas of poor soil ‘sorry soil’, because they are sorry examples of what good soils should look like. Life on earth depends on that upper layer of soil because it nurtures the growth of plants, filters our water, and provides habitat for a wide range of living organisms. Soil and plants go together, but when the soil gives out, the plants go away, and we end up with ‘sorry soil’.

Soil becomes ‘sorry’ when it is abused or neglected. Abuse can take the form of stripping off the top soil and leaving the clay subsoil. Perhaps its caused by compaction, when heavy equipment, cars, or even excessive foot traffic causes soils to pack down and become impervious. Neglect usually takes the form of soil erosion, when top soil is left unprotected by vegetative cover and washes away in heavy rainfall events. Soils can also suffer from nutrient deficiencies when they are over cropped or not replenished with lime and fertilizer when needed.

Soils have three basic layers called A, B, and C horizons. The A horizon is the top soil, and it should be loose and easily dug or tilled. When it rains water should flow through good top soil freely. When the top soil is removed or washes away through erosion, the B horizon is what is left. Here in the Piedmont of North Carolina, the B horizon will be red or orange in color and it will be clay. Red clay is much more difficult to work with than a sandy top soil, and it is easily compacted and can be very difficult for water to penetrate. The C horizon is usually a combination of rock and clay and is what is known as soil parent material. Some soils in the southeast may also have an O horizon, which stands for organic matter. Organic matter is composed of plant debris and decomposing plant parts and is found at the top of the top soil. It is difficult to maintain an O horizon in the south because organic matter breaks down rapidly in our heat and humidity. It is possible to find an O horizon in pastures and lawns with permanent grass cover and the forest floor has a substantial O horizon due to the accumulation of leaves and decaying plants. It is rare to find an organic layer in cultivated or plowed soil because the cultivation speeds up the decomposition of organic matter. If you have all 3 or 4 layers of soil on your property the best way to maintain it and even build it up is to maintain vegetative cover on the soil, and the heavier the vegetation the better. Vegetation holds the soil in place, but also adds organic matter and the roots help open up the soil and provide food for soil improving earthworms.

So if you have a patch of sorry soil in your yard how do you fix it?  The first step is to loosen the hard soil. You do this by digging up the soil. Aeration will not loosen compacted soil. Lawn aerators make small holes in the soil but they actually compact the soil in the individual holes. Grass seed will germinate more readily in holes created by aerators but aerators will not correct compacted soil. Hard soil needs to be disturbed at least 10 to 12 inches deep. This is best done by manual digging with a shovel or digging fork or by use of a backhoe. Once the soil is loosened, add and incorporate powdered or pelleted dolomitic limestone and organic matter such as mature compost to improve the chemistry and texture of the newly turned soil. Most of the lawn grasses we grow are not native to North Carolina and need a soil pH of 6.0 or higher. Sorry soils will have a pH of 5.0 or much lower and few plants will grow in soils with a low pH.

How do you know how much to add? Have a soil test done on your lawn and your bad spots in particular and apply lime as directed by the soil test report. Soil tests are done by the NC Department of Agriculture. They cost $4 Dec-Mar and are FREE Apr-Nov (http://www.ncagr.gov/agronomi). In ForsythCounty you can bring soil samples to the Cooperative Extension office and we'll send them to Raleigh for you. Make sure you read how to properly collect a representative sample (http://www.ncagr.gov/agronomi/pdffiles/samhome.pdf). If you don’t have a soil test, apply lime at 75 pounds per 1000 square feet and till it in. Compost or other organic matter such as pine bark fines should be applied at the rate of 1-2 inches deep on top of the soil and tilled in. Once your soil has been deeply tilled, limed, and had compost or other organic matter incorporated, plant grass seed or plant shrubs, trees, or perennials. You will be amazed at how well they will grow in your newly revitalized soil.

Learn more at Forsyth Cooperative Extension workshops held throughout the County!

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