Composting

Compost is one of the most valuable resources for beautifying your landscape; and it is virtually free. The leaves you rake, the grass you mow, and the branches you trim are some of the ingredients you can use to make compost.

Finished compost is dark and has a pleasant smell. It is produced when organic matter, such as garden, lawn, and kitchen waste, is broken down by bacteria and fungi.

Use it throughout your landscape - till it into gardens and flower beds, add it to the soil when renovating your lawn, or sieve it and use it in potting soil.

Compost is made from brown materials such as hay, straw, and old leaves, and green organic matter such as grass clippings, scraps, and manure.

There are many benefits from composting:

Compost improves the structure of soil. With the addition of compost, sandy soils hold water better, and clay soils drain faster.

Compost reduces soil erosion and water run-off. Plant roots penetrate compost-rich soil more easily and hold the soil in place. Water can run down into lower soil layers, rather than puddle on top of the ground and run off.

Compost provides food for earthworms, soil insects, and beneficial micro- organisms. It assists the soil in holding nutrients, thus lessening the need for chemical fertilizers and preventing the leaching of nitrogen into water. It promotes healthy plants which are less susceptible to diseases and insect pests, reducing the need for pesticides.

Composting in your backyard recycles wastes which might otherwise fill up landfills. Leaves, grass, and debris - often raked into the street for collection - tend to clog storm drains and street gutters, and are costly to collect, but make excellent compost materials.

Once you decide to compost, you must decide upon a method. The method you choose will probably depend on the space you have.

A compost pile can be as plain or fancy as you want - you don't even need a bin to make compost. But if you plan to produce compost regularly, consider a permanent compost bin.

Some gardeners build separate bins for each stage of the compost process - one for fresh plant refuse, another for the actively composting pile, and a third for the finished compost. When building your own bin, keep one side open for easy access. Also, leave spaces between blocks or planks for aeration - air is essential to the rapid decay of organic materials.

The size of the compost pile determines how effective it will be; piles smaller than 27 cubic feet (3 x 3 x 3) do not hold sufficient heat for the composting to be effective, and piles larger than 125 cubic feet (5 x 5 x 5) do not allow sufficient oxygen to reach the center. Be sure your compost pile is a manageable size.

Locate your compost pile on a well-drained site. You can built your pile gradually in layers and then turn it to mix the layers; or, if you have sufficient material, it can be mixed and blended at one time.

On the bottom, use a 3-inch layer of coarse plant material, such as small twigs or chopped corn stalks, or use a wooden pallet.

Next, add about 8 to 10 inches of leaves or other dry organic wastes.

For nitrogen content add 2 to 3 inches of fresh grass clippings or fresh manure. Alternatively, add about one-third cup synthetic fertilizer (36-0-0) per 25 square feet of surface area. A sprinkling of soil or a compost starter added to the pile will introduce microorganisms.

Moisten the pile as you add leaves and other dry material. Mix the materials thoroughly.

Shape the pile so its center is lower than its sides, to help water flow into the pile.
Keep the pile moist, but not soaking wet. Within a few days, it should heat up. Once a month, turn the pile with a pitch fork, putting the outside materials on the inside, and vice versa.

The plant materials should decompose into compost within five months in warm weather. However, composting may be completed in one or two months if the materials are shredded, kept moist, and turned regularly to provide good aeration.

If you have limited space, consider a compost tumbler. There are several types: crank operated drums, center-axel drums, base rolling drums, and roll-around spheres. There are also ones with two bins, one for mature compost and another for “cooking” the next batch.

Whichever unit you choose, you should be aware of certain operational factors:

The proportion of green material to brown is more crucial in a closed tumbler than in an open pile. If you don't add at least 40 percent browns, you'll end up with a slimy, smelly mess instead of compost. If nothing else is available, keep a bag of leaves or a bale of straw handy and use it as necessary to maintain the balance.

All tumblers are pest-proof to rodents, dogs and other animals, but not to insects. When you open a tumbler, be prepared for a cloud of gnats to emerge.

Monitor the moisture content. Tumblers retain moisture better than open piles, so you don't need to add much. Usually, grass clippings alone provide more than enough moisture. Your working pile should feel like a damp sponge. If it’s wetter than that, leave the door open awhile so it can dry out. Occasionally you may have to add a small amount of water. If so, add no more than a cup at a time, and be sure to tumble the contents after each addition.

Air is crucial to the composting process. Periodically check to ensure the vents in your composter haven't been clogged by organic material. If you think the mix isn't getting enough air, rotate the tumbler more frequently. (2)

Grass clippings and fall leaves are abundant compost materials for most homeowners. Weeds free of seedheads, and crop residues, such as vines and leaves, are other sources. Never include weed seed or perennial roots or stems that might become established. Collect vegetable and fruit peelings, coffee grounds, crushed eggshells, and similar kitchen waste for your compost pile. Don't use meat waste; it attracts animals. Include additional materials, such as sawdust, manure, hay, or straw.

For composting kitchen wastes, consider a composting crock. Available from many mail order sources, it is an air-tight container that can be kept on the counter or under the sink to store wastes between trips to your composter.

In summary, keys to good composting include:

The carbon/nitrogen ratio: A mixture of dry leaves, sawdust, or other sources of carbon combined with manure, green plants, or fertilizer for nitrogen (approximately 4:1 by volume).

The presence of microorganisms: A few shovels full of rich garden soil or compost will supply these.

The moisture level: The pile should have the moisture of a well-squeezed sponge. Add water as needed.

The oxygen level: A compost pile should be turned periodically to promote decay of its contents. Turning the pile adds oxygen, so the more you turn it, the faster it breaks down.

The particle size: The finer the particle size, the more surface there is for microorganisms to work. Shredding leaves and larger materials generates compost faster.

I’d like to add a warning. If you use chemicals to kill weeds in your lawn or garden, do not use those weeds in your compost. The chemicals that kill the weeds will still be present, and using any compost containing those chemicals in your garden will kill your garden as well.

Written by members of the Heart of Virginia Master Gardeners

posted 3/1/07