Compost is a nutrient-rich material created by the aerobic biological decomposition of organic matter, such as plant debris and animal manures. Aerobic decomposition means that oxygen is present during the biological process. Compost literally cooks because if done correctly it heats up to approximately 140 degrees Fahrenheit through the action of microorganisms, destroying weed seeds and pathogens and breaking down almost all potentially toxic chemicals.
Good compost starts with adding or mixing 25 parts browns with one part greens in a mix. The browns are made up of any dried up organic material: leaves, branches (small pieces work faster), sawdust, dry grass, etc. The greens are made up of green plant materials such as: green grass, green leaves, green garden residue. To this mix you should add some soil, old compost, animal manure (no dog or cat doo), so as to speed the process along, this adds nitrogen and microbes. The greens and browns should be layered or mixed in the compost pile. Adding too much greens in one layer could cause anaerobic activity which could result in a unpleasant smell. In order for the compost pile to work, it must be kept moist, but not soggy. After a time the pile should heat up due to the decomposition process, if heat is not present, the pile may need more water, more air, more nitrogen or more size. As the materials in the compost pile decompose, the pile will shrink to about half its original size. The time needed for decomposition depends largely on weather and time of year.
Finished compost is neutral in smell and pH and will not burn plants. Anaerobic decomposition occurs if there is not enough oxygen, and it is very smelly. The nutrient content of finished compost varies, depending on if the compost is made using manures, which will generally be higher in nitrogen and compost made mainly from plant materials, will usually have lower available nutrients.
Most soils, particularly ones in Wyoming, are short of organic matter and the benefits of organic matter are almost endless. Most problems with our soils can be prevented, cured or improved by the addition of good organic matter.
The health of any landscape and the health of plants can be improved with the addition of organic matter. The organic material in the soil increases the microorganisms in the soil which benefits the plants. One goal is to have at least 5 percent organic matter in the soil with the proper balance of nutrients.
Using compost to create good planting soil rather than topsoil, uses less material and frequently less labor. Rather than adding 6 to 12 inches of topsoil, you can plow in two to four inches of compost. The costs and benefits will vary depending on the scale of the project you are working on and the specific needs of your site and the type of landscape you are working with. Topsoil so many times is a gamble, you may receive quality soil or you may not. Adding compost to clay soils is virtually guaranteed to create soil plants will thrive in at a lower cost than adding topsoil.
If you are landscaping in sandy soil, you will probably need to add compost and some topsoil.
I like to add organic matter during the year to the flowerbeds and the garden then work it into the ground in the fall. I have also used some very big pieces of organic matter (wood chips, corn stalks, etc.) and rototilled them into the garden in the fall and was surprised with how well it had broken down over the winter. When using grass clippings for compost be careful if herbicides have been used (weed killers) since those residues may still be there. Also, using manure weed seeds and herbicides may also be present even over several years of storage. The more organic matter we can put into our soils the better the plants will grow.
Scott Hininger is with the Sheridan County Extension office.