Compost Uses Compost is a valuable resource for soil improvement. Compost is useful to the home gardener, in the restoration of landscapes where topsoil has been removed or compacted, and to restore agricultural and forest lands. Compost is typically applied in three ways: To mulch or top dress planted areas To amend soil prior to planting As a component in potting mixes Mulch: Compost can be used to mulch annual and perennial plantings, shrubs and trees and as a top dressing for lawns. Recommended uses of compost as mulch and top dressing are show below: Using Compost as Mulch On flower and vegetable beds: Remove weeds and grass that may grow through mulch. Screen or pick through compost to remove large, woody materials. They may be unattractive, and will compete for nitrogen if mixed into the soil. Apply 1-3 of compost over the entire bed, or place in rings around each plant that extend as far as its outermost leaves. Always keep mulches a few inches away from the base of the plant to prevent damage by pests and disease. On lawns: Use screened commercial compost, or sift homemade compost through a ½ or finer mesh. Spread compost in ¼ - ½ layers after thatching, coring, or reseeding. On trees and shrubs: Remove sod from around trees and shrubs as far as branches spread. If this is impractical, remove sod from within a minimum of 4 diameter circle around plants. Use coarse compost or materials left after sifting. Remove only the largest branches and rocks. Spread 1-3 of compost. For erosion control: Spread coarse compost, or materials left after sifting, in layers 2-4 deep over entire planting area or in rings extending to the drip line. Mulch exposed slopes or erosion-prone areas with 2-4 of coarse compost. Soil Amendment: Compost can be used to enrich garden beds before planting annuals, ground covers, shrubs and trees. Recommended applications for different plants are shown on the next page. Amend soils by mixing compost thoroughly into the top 6-12 of existing soil. Do not lay compost on top of the existing soil without mixing: the interface where they meet can become a barrier to penetration by roots and water.
Using Compost as a Soil Amendment In flower and vegetable beds and ground covers: Dig or till base soil to an 8-10 depth. Mix 1-4 of compost through the entire depth. In established gardens, mix 1-3 of compost into the top 6-10 of soil each year before planting. On lawns: Till base soil to a 6-12 depth. Mix 1-2 of finely textured compost into the loosened base soil. Around trees and shrubs: Dig or till base soil to minimum 8-10 depth throughout planting area, or an area 2-5 times the width of the root ball of individual specimens. Mix 1-4 of compost through the entire depth. Do not use compost at the bottom of individual planting holes or to fill the holes. Mulch the surface with wood chips or coarse compost. Potting Soil and Seed Starting Mixes: Sifted compost can be used as part of a potting soil for use in planters, house plants, or starting seedlings in flats. Compost is a good component in potting soil: it stores moisture and supplies not found in sand, bark, peat and pumice. Use only very mature compost to avoid burning plants or tying up nitrogen in the soil. Water new plants until water runs out of the bottom of container to wash out any harmful salts. Use compost to make up no more than 1/3 of the volume of a potting mix. Some simple recipes for making compost mixes are shown below. Or use compost to enrich purchased potting mixes. Using Compost in Potting Mixes For starting and growing seedlings in flats or small containers: Sift compost through a ½ mesh. Mix 1 part sifted compost, 1 part coarse sand, and 1 part Sphagnum peat moss. Add ½ cup of lime for each bushel (8 gal.) of mix. Use liquid fertilizers when true leaves emerge. For growing transplants and plants in larger containers: Sift compost through a 1 mesh or remove larger particles by hand. Mix 1 part compost; 1 part ground-up bark, Perlite or pumice; 1 part coarse sand; and 1 part loamy soil or peat moss. Add ½ cup of lime and ½ cup of 10-10-10- fertilizer for each bushel (8 gal.) of mix. (An organic fertilizer alternative can be made from ½ cup bloodmeal or cottonseed meal, 1 cup of rock phosphate, and ½ cup of kelp meal. This fact sheet was adapted with permission from The Composting Council s National Backyard Composting Program Training Manual (1996).
Lasagna Composting The Lasagna Method is a way of structuring a compost system so that maintenance is minimized, pests are deterred, and both large and small amounts of compostables can be handled at any time. This simple layering system can be used in any bin. Initial Layer: The first layer in your bin should be a loose layer of twigs and branches stalky material that will not compress as the compost bin fills up. The purpose of this layer is to build in a way for air to reach the center of your pile. Oxygen ensures that the decomposition will not generate unpleasant odors. Brown Layers: These can be made of straw, dried leaves, wood chips, sawdust, even torn up paper. All these materials are carbon-rich, supplying a critical food source to the decomposer organisms. The brown layers help to balance the moisture in a pile, since the brown materials are usually much drier than the food scraps in the green layers. These materials are also usually coarser, so they create a porous structure that allows air into the center of the pile and allows excess water to escape. Finally, the brown layers serve as a visual and physical barrier to pests, by filtering food smells and putting the food scraps out of reach of insect pests. Green Layers: These are nitrogen-rich materials, supplying another critical food source for the decomposers. Acceptable greens include food scraps from meal preparation, inedible leftovers, grass clippings that are too long to be left on the lawn, garden weeds, manure, etc. DO NOT include meat, oily materials, dairy products, or bones. These risk attracting pests to the compost area.
Layering Technique: Alternate green and brown layers, starting with a brown layer and always ending with a brown layer so that no food ever shows. Brown layers should be two to three times as thick as green layers. Green layers should be no more than 1 or 2 inches thick. Brown layers should be shaped like saucers lower in the center and higher around the edges so that the next green layer can be kept to the interior of the pile with no food showing on the edges. Routine Tasks: Whenever your indoor collection container is ready to be emptied, take it out to the compost bin, spread the food scraps on top in thin layers keeping them away from the edges! and cover them with a generous layer of browns. Wash out the kitchen container and return it to its spot, lined with a fresh piece of newspaper to make cleaning easier. Optional Maintenance: With this layering technique it is not necessary to turn the compost. However if you wish to get the compost finished sooner, you may choose to turn the bin contents. Compost forks or other digging tools may be used to stir and mix ingredients right in the bin. Alternatively, if it is possible to simply lift off or undo the existing bin, then you can get easy access to the unfinished compost. Reset the empty bin, put down an initial layer of stalky material, and turn the partially finished compost into the new bin. This will mix the ingredients, and bring the materials that were on the outside edges in to the middle where they will start to break down faster. Harvesting Finished Compost: The materials on the bottom layers will tend to finish first, since they started first. If there is unfinished compost on top of the bin, transfer the unfinished compost to a new bin. The finished compost may then be harvested and put to use. The length of time it takes for compost to be ready depends on many factors, so it is difficult to give a general rule for how long it will take. Weather conditions, the size of your bin, the type of materials included, the amount of turning, and other factors all play a role in determining the speed of breakdown. Generally, a year should be sufficient. But there are ways to test whether or not the compost is done, if you are not sure. Check with Cooperative Extension for more information on assessing and using your compost.
Is It Done Yet? Testing Compost Maturity The degree of doneness that is appropriate depends on how the compost is going to be used. If you are using compost as a topdressing or mulch on garden beds, it is appropriate to use coarser, somewhat less finished compost. If you are going to be working compost directly into the soil close to planting time, then the compost should be mature and should be fine enough to fit through a ½ inch screen. This excludes wood chips or other coarse material that might not yet be fully decomposed. For making up a potting soil for germinating seeds, the highest level of maturity is required and a finer screening such as to ¼ inch or even 1 / 8 inch would be desirable. With respect to soil incorporation or potting mixes, the reasons for being careful about maturity are summarized as follows in A Green Guide to Yard Care by Texas Natural Resource Conservation Commission, 1/98: Using compost before it is ready can damage plants. Undecayed brown materials in the soil can temporarily reduce plant-available nitrogen. Undecayed green materials can harbor pests and diseases. Immature compost can also introduce weed seeds and root-damaging organic acids. Simple checks of compost maturity: Compost should be dark, crumbly, with no recognizable food. Compost should have an earthy smell. but these alone are not enough! If you know your compost is already a year or two old, you don t have to worry. But if you are trying to get compost into your garden quickly, it s best to take a little time to test it further, especially if you will be planting the area soon. Two additional tests are described below: The Jar Test : Put some compost in a jar, add water to make it soggy, and seal the jar tightly. Leave it alone for a week, then open the jar (carefully!) and check for odor. If it smells like nice wet earth, then the compost is done. If you notice bad odors then it means that the materials in the compost were not sufficiently decomposed and anaerobic organisms have gone to work on the nutrients that remain. These anaerobes produce unpleasant odors as a by-product, so bad smells are the indicator!
The Germination Test: First, make up some compost tea : mix equal amounts of compost and water and let that sit for 5 minutes or so, stirring occasionally. Pour off the tea into another container. (The remaining solids can be returned to your compost pile.) Then soak a few seeds, such as cress, lettuce, radish, or cucumber in the tea and an equal number of seeds from the same packet in distilled water for 2-3 minutes. Lay each set of seeds, clearly labeled, on dampened paper towels on a plate or tray and keep them warm and moist for a few days, until they start to sprout. It may help to place a layer of light plastic over the tray, to hold the moisture in. Check the seeds every day for 3-4 days. In general, if the water-treated seeds germinate better, then the compost has not aged enough. More specifically, look for differences in how long it takes for the radicle (the early root shoot) to emerge; differences after 3-4 days in the number of seeds in each set that have germinated; and differences in the length of the radicle after 3-4 days. Since you are only looking at a few seeds, small differences will not be significant. However if you see substantial delays or other differences in the tea-treated seeds then it indicates that the compost is not yet ready for using for planting. It may be that the compost has too high a level of natural salts and it simply needs to sit and cure for longer, with exposure to the weather. If you are testing in the Fall, you may wish to mix the compost into the garden bed and wait until Spring to plant. Many kinds of seeds will work, and testing the ones you will actually be planting would be a good strategy. Cress seeds should sprout very quickly, which makes them desirable for quick testing. The others listed above are also quick to germinate, and the plants are known to be relatively salt-sensitive, so they make good test candidates. Cucumber and radish seeds do not have a very heavy seed coat, so they are more likely to be sensitive to chemicals in the test. Tomato seeds are very resilient, so they are not particularly good as test seeds.
SYMPTOM POSSIBLE CAUSE POSSIBLE SOLUTION/ALTERNATIVE Compost pile is damp and warm in the middle, but nowhere else. Compost pile isn t heating up. Compost pile isn t heating up. If it seems damp and sweet smelling, it may be a lack of nitrogen. Not enough oxygen. Cool weather The pile may be too small. Pile was built over several months. Compost may be finished. Mix in fresh grass clippings, manure, blood meal or other material high in nitrogen. If it is difficult to turn the pile, create holes in the pile and add the nitrogen-rich material. Turn or fluff the pile. Increase pile size and/or insulate with straw or a plastic cover. Gather enough material to form a pile 3 by 3 by 3 and/or insulate the sides and cover the top. Don t worry about it. Let pile compost cold. Check for finished compost. If it looks dark and crumbly and smells earthy (not moldy or rotten), it may be done. Use it! (If unsure, call for more info.) The pile is dry throughout. Lack of water. Turn the compost and add water. Moisten new materials before adding to the pile. If the pile is out in the open, consider covering with a straw or plastic cover. The pile should be as damp as a wrung-out sponge throughout. Matted, undecomposed layers of leaves or grass clippings. Large, undecomposed items. Compost pile has a bad odor like a mixture of rancid butter, vinegar and rotten eggs. Compost pile has a bad odor like ammonia. Compost pile is attracting rats, raccoons, dogs, flies or other pests. Troubleshooting Compost Piles The pile may be too small. Compaction, poor aeration. Size and composition of materials. Not enough oxygen, too wet. Not enough oxygen, compacted. Pile may have too much nitrogen. Possibly inappropriate food scraps: meat, fat, bones, or byproducts Gather enough material to form a pile 3 by 3 by 3 and/or insulate the sides and cover the top. Break up layers with garden fork or shred them, then re-layer pile. Avoid adding heavy layers of leaves, grass clippings, hay or paper unless first shredded. Screen out undecomposed items, reduce size if necessary and use in a new pile. Turn the pile and add course dry materials such as leaves, straw, or corn stalks to soak up excess moisture. Protect the pile from rain using a plastic film or other cover. Turn the pile and shake materials apart to aerate. Add materials high in carbon such as shredded leaves, nontreated wood chips, sawdust or shredded newsprint and aerate. Avoid adding such material; use a rodent-resistant bin with a top, bottom and sides. Bury non-fatty kitchen by-products 8-12 deep in the pile. Compost pile contains earwigs, slugs and/or other insects. Pile is composting correctly Insects are a good sign of a productive compost pile. Note: slugs live happily in compost piles. If the pile is next to a garden, barriers can be placed between the pile and nearby garden with traps, metal flashing, etc. This fact sheet was adapted with permission from The Composting Council s National Backyard Composting Program Training Manual (1996).
STOPPING TROUBLE BEFORE IT STARTS Material OK? Comments Barbecue ashes/coal No Contains sulfur oxides; bad for garden Cardboard (CC) Yes Glue probably organic Coffee grounds (N, P) Yes, but Acidic Cooked food scraps Yes, but Low in nutrients and may attract animals if it contains oils or meat/dairy Cornstalks, cobs (C, K) Yes, but Must be mixed with nitrogen-rich material Dishwater No Most dishwashing soaps contain perfumes, greases, sodium Dryer lint Yes This is a good one! Eggshells Yes Crush; source of calcium Fish scraps No Can attract animals; bury scraps in a trench Grass clippings (N, P, K) Yes, but Not from lawns treated with pesticides; good nitrogen source when fresh, carbon source when dried Grease No Does not break down well in backyard system; attracts animals & slows composting process Kitty litter No Likely to contain disease organisms Manures - horse, cow, sheep, goat, Yes, but Horse manure more likely than others to contain weed chicken, pig seeds; compost thoroughly Dog, cat & bird manure No May contain disease organisms Mushroom compost Yes, but May contain fungicides; low in nutrients, but good soil builder Newspaper (CC) Yes Shred for compost, use shredded or flat for mulch; colored sheets now considered OK Oak leaves (C) Yes, but Acidic Pine cones (C) Yes, but Decompose slowly; acidic Sawdust, wood shavings (CC) Yes, but High in carbon and must be mixed with nitrogen-rich material Weeds Yes, but Only if weeds are green and seeds have not matured Wood ashes (P,K) Yes, but Use small amounts; highly alkaline N - Nitrogen, P - Phosphorus, K - Potassium, C - Carbon (All plant and animal materials contain carbon. A single C needs to be accompanied by nitrogen or it will rob nitrogen from the soil.) CC - Extra large amounts of carbon, so needs additional nitrogen. Compost Chart adapted from National Gardening Magazine, June 1986
Continue composting throughout the year, despite winter winds, dropping temperatures and snow. Although the decomposition process usually slows down in cooler weather, compost piles will keep working all year long. Residents of your pile, like bacteria, molds, mites and actinomycetes can survive the cold. However, to prolong their active life over the winter, they will need warmth, food, air, and moisture. Follow the tips in this fact sheet to optimize your composting in winter months and welcome spring with a productive, healthy compost pile. Late fall preparations Collect bags of dry leaves from your lawn and your neighbors. Stockpile excess dry leaves in large plastic garbage bags or covered garbage cans for use throughout the year. Harvest finished compost from your pile to make room for your winter additions. Since the decomposition process is slower in the winter, you may need the extra room. Use the finished compost in your garden or store it in a dry place for the spring. Over the course of the winter 1. Continue layering browns and greens Adding a lot of compostable material to your pile will shield the critters responsible for decomposition from the elements. Garden waste, spent perennials, sod, and - of course - the ubiquitous fall leaves are good, abundant choices in autumn. It is always best to layer greens (kitchen scraps, fresh garden waste) with browns (dead leaves, straw, newspaper). This ensures the right ratio of carbon to nitrogen, helps aerate and provides adequate drainage in the pile all of which contributes to next spring s harvest of "black gold." Turning the pile in the winter is not necessary, since it may result in a loss of heat from the middle of the pile. 2. Insulate your bin or build a wind break Insulating your bin will protect it form the harsh winter winds and cold. While the outside of you bin may freeze, the inside can still cook. If you find yourself with an overabundance of leaves, pile them on! As you produce greens (kitchen scraps) over the winter, tuck them in under the insulating layer. You can provide extra insulation by surrounding your bin with black bags of leaves or straw/hay bales. Or try creating a windbreak with a tarp. 3. Maintain a pre-compost bucket To reduce your cold winter trips to you bin, start a pre-compost bucket. You can use an empty bucket or trashcan in which you place your kitchen scraps. However, be sure to layer them with adequate browns to prevent smells. Add these materials to your outdoor bin whenever convenient or before your pre-compost bin gets too heavy. 4. Reduce particle size of browns and greens The cold weather slows down the compost process. Smaller particle sizes of greens and browns provide more surface area to speed decomposition. Set up a cutting board for compost and chop up your food scraps before putting them in the bin. Leaves can be shredded with a lawn mower or trimmer. Early spring maintenance Winter Composting If your pile should freeze over the winter, it will return to active duty once thawed. Once it does, you will be happy that you took the time to layer your greens with browns. One common mistake is to pile all the winter s kitchen scraps onto your pile without layering or mixing in browns. All-greens piles are almost always stinky! If your pile is excessively wet due to the spring thaw, turn it and add more browns to soak up this moisture.