By April Sorrow
University of Georgia
“Incorporating finished compost mulch into vegetable garden beds or plant beds amends the soil and allows water and air to filter through the soil better,” said Bob Westerfield, UGA Cooperative Extension horticulturist. “There is not as much run off and the nutrients infiltrate better.”
Using nearly-finished compost as mulch helps plants retain moisture and prevent weeds.
“Organic fertilizers make the plants healthier,” Westerfield said. “And, when they are healthier they require less water.”
Compost is decomposed organic matter used as a soil conditioner and fertilizer. In heavy clay soils, compost reduces compaction, helps increase aeration and helps water better infiltrate the soil. In sandy soils, it helps the soil retain both water and nutrients.
Compost is made from a mix of brown and green organic materials. Brown compost materials may include dry, dead plant materials, autumn leaves, dried grass clippings, shredded paper and wood chips. These provide carbon.
Green compost materials, such as fresh plant products, kitchen fruit and vegetable waste, coffee grounds and tea bags, provide nitrogen.
Westerfield says to include more brown items than green. The ratio should be 3 to 1. Don’t add meats, bones, grease or other animal-based food waste. They can smell bad and attract rodents.
Materials should be added in layers, alternating brown and green. A pile of compost can take three weeks to six months to process, depending on the care. Adding fresh material to a pile can cause the process to take longer.
The key to composting is to keep the pile moist and to allow for air flow. “The composting cycle will work faster if the pile is kept moist and turned frequently,” he said. “The more you agitate the pile the faster it will compost.”
Rain water and turning the pile a few times a month should maintain moisture. Water should be added only to keep the pile moist, not wet.
“It is nice to have two or three bins so you can have several stages of compost,” he said. Westerfield suggests removing finished compost from a pile and keeping it contained in a separate bin for use.
“Some people are disappointed because they fill the bin up and when it becomes compost, they end up with 10 to 20 percent of what they put in,” he said. “As it biodegrades, its volume drastically reduces.”
Fertilizer can be added to the pile. A little 10-10-10, as well as a few scoops of garden soil, are suggested. Don’t add lime to the mixture.
Another option in composting is vermicomposting, which uses worms to help break down the organic waste.
While composting provides organic material valuable to plants, most people view composting as a form of recycling. In many counties, landfills no longer accept green materials.
“It’s a way to recycle waste and save money by producing a product from trash you would otherwise have to buy,” Westerfield said.
(April Sorrow is a news editor for the University of Georgia College of Agricultural and Environmental Sciences.)
(April R. Sorrow is a science writer with the University of Georgia Public Affairs Office.)