Composting is basically Mother Nature’s way of recycling nutrients. They are returned to the soil in order to be used again. Compost is decayed organic matter that is dark in color, crumbly in texture, with a distinctive earthy smell. When used in the garden, compost is like gold to gardeners. The uses of compost are many. It can be used to enrich flower and vegetable gardens, to improve the soil around trees and shrubs, as a soil amendment for houseplants and planter boxes. When screened, compost can be used as part of a seed-starting mix or even as a top-dressing for lawns.
The first step toward improving overall plant health is to improve your soil and compost is the secret remedy. Organic matter improves plant growth in a number of ways. If you have clay soils, adding compost can help break up heavy soils and improve their structure. Adding compost to dry, sandy soils helps improve its water and nutrient-holding capacity. Compost adds essential nutrients to any kind of soil. It also feeds all those beneficial soil organisms that make up a healthy, living soil.
So, what can you compost? Basically, anything that was ever alive can be composted. The easiest things to put in a compost pile are waste from the garden and yard — leaves, weeds, grass clippings, dead vegetable and annual plants, after they’ve been frosted. But there are some things you do not want in your compost pile. It’s never a good idea to add weeds that have gone to seed or plants that have a disease. Weed seeds and disease pathogens may not be killed during the compost process. You can also compost things from your kitchen, like vegetable scraps, coffee grounds or egg shells. Stay away from meat, bones, dairy products and fats. Pet waste should not be added to your compost pile either.
There are a variety of methods that you can choose from for home composting. These include placing materials in open piles, burying materials in pits or putting materials in bins. If you want a “hot” compost pile, the minimum dimension to keep sufficient heat in the pile is 3 feet-by-3 feet-by-3 feet (1 cubic yard). The largest your compost pile should be is about 5 feet-by-5 feet-by-5 feet (125 cubic feet) in order to allow enough air to reach the center of the pile.
The actual work of composting is done by microorganisms and they have a few basic requirements - air, water, temperature and the right food. Composting garden waste is an aerobic process, so it needs oxygen to work. Oxygen is provided in two ways: by turning the compost pile or by building the pile so surface air can get to the center. When a pile doesn’t get enough oxygen, it will go anaerobic and smelly odors are a result. Microorganisms also need water. The moisture content should be between 40 and 60 percent, about as moist as a wrung-out sponge. Too wet and anaerobic conditions result; too dry and the decomposition process will slow down.
Composting microorganisms, bacteria and fungi get their energy from carbon sources, such as leaves, wood chips or paper. Nitrogen is necessary for population growth, but too much nitrogen can result in ammonia and other unwanted odors. Materials categorized as “brown,” such as straw, contain more carbon than nitrogen whereas “green” materials such as green grass or freshly pulled weeds have more nitrogen.
In order to get a nice hot compost pile, there is a certain ratio of brown to green material that should be used. This is called the C:N ratio; C for carbon and N for nitrogen. The preferred C:N ratio is 30 parts carbon (browns) to 1 part nitrogen (greens). Layering your browns and greens can help with aeration and moisture. The brown layer should be thicker than the green layer.
As the microorganisms are working, they generate heat. When temperatures rise above 140 degrees F, the organisms start to die. To prevent overheating the pile, it will need to be turned at this point. The composting process will slow down as the microorganisms use up most of the readily decomposable matter. The compost will have a dark color and a granular texture. At this point, the compost can be left to cure and will continue to improve until it is ready for use. Be patient. It can take four months to a year before the compost is ready for use, depending upon the method you choose.
How do you know when your compost has finished cooking? Simple — smell it and look at it! Finished compost should be dark and crumbly. It will smell like freshly turned earth. Very little of the original materials should be recognizable. The pH should be close to neutral (7.0) and it should have a fairly constant temperature, around 8 to 10 degrees F above air temperature.
If you want to have a supply of brown material to use during the spring and summer, you can collect dry leaves in the fall. If you have a dry place to save them you, can store them in biodegradable bags, otherwise, store them in garbage bags or garbage cans with lids. One large garbage bag is enough leaves to add to your pile for a month or two.
As the temperature falls, the decomposition process in your compost pile will slow down, but don’t worry, you can start to compost again next spring. Your plants will thank you.
Resources for this article include: Cornell Waste Management Institute, University of Maine, CCE Tompkins County.
Have a gardening question? The Master Gardener office is open. Please wear a mask when visiting the Cornell Cooperative Extension office and check in at the reception window. Master Gardener volunteers are normally in the office Monday through Friday, from 10 a.m. until noon. You can stop in at our CCE office at 420 E. Main St., Batavia. Call (585) 343-3040, ext. 127, or e-mail them at email@example.com. Visit our CCE website at genesee.cce.cornell.edu or like us on Facebook www.facebook.com/CCEofGenesee.
Garden Talk on Oct. 1 will be held on Zoom and will start at noon. The topic will be “Easy Preserving.” Register at the CCE website events page - http://genesee.cce.cornell.edu/.