Practice No. 13. Compost and Recycle Yard Waste
Adding compost to soil is one of the key practices in creating organic landscapes. Compost can be used to inoculate the soil with beneficial microbes and stimulate other life to the benefit of the soil food web and garden ecology. Compost should be used in re-mediating areas that have been treated with herbicides, pesticides, fungicides and chemical fertilizers.
Compost happens! We should be grateful indeed that it does. Organic substances will eventually decompose and become food for plants, part of our planet's great recycle. Of course, material decays faster if the pieces are small, like leaves, or longer as in the case of tree trunks. Decomposition is quicker in humid climates than in arid regions.
For the home gardener, compost typically consists of decomposed plant debris from our gardens: grass clippings, autumn's fallen leaves, pruned stems, limbs and branches, unwanted, spent or dead plants, and vegetables, fruits, and kitchen scraps. The simplest form of composting is laying plants directly on the soil, such as pulling a weed and leaving it to provide nutrients through its decay in place and mowing grass with a mulching mower. Or burying plants with a light covering of soil. Organic materials can be composted simply by layering in a heap, without the aid of a structure. If using a structure, the size should be no more than 3 feet tall, but can be any length and width -- whatever works well for you to turn the pile.
Benefits of Compost
Composting and adding composted organic matter to the soil provides many benefits:
- Compost aids in the formation of better soil structure by the action of microbial life exuding sticky gums and resins that form better soil aggregates.
- Compost promotes the growth of mychorrhizal fungi, the beneficial fungi that grow in decomposing organic matter.
- Decomposed organic matter increases growth promoting fungi that help control diseases, root rot and damping off fungi.
- Compost lessens soil erosion.
- Compost balances the pH of the soil over time. Balancing the pH allows for better mineral absorption.
- Earthworm populations increase in well composted soil.
- Compost helps to conserve water in the soil, storing it for later use.
- Compost provides nutrients for soil microbes and plants.
- Compost acts as a buffer to chemicals, reducing toxicities.
- Compost moderates soil temperature and promotes earlier soil warming.
- Composting recycles waste products, reducing landfill space.
Customized Bacterial or Fungal Dominated Compost
The biological side of the soil is the most promising segment of agricultural research today. Scientists are discovering not only the relationship between beneficial microbes and plants, but individual microbes to individual crops. For the home gardener, we may not be concerned with individual microbes for a particular grass variety or tree, but we can tailor our organics in a more general manner.
Trees, shrubs and most perennials prefer fungal dominated compost, while most annuals – flowers and vegetables-- and grasses – turf grasses included – prefer bacterial dominated compost. Fungal dominated compost contains a higher percentage of brown organic material, higher in carbon, C (higher C:N ratio). Brown material includes autumn leaves, twigs, straw, bark, wood chips, and branches. A simple recipe for making fungal compost would be:
- 5 – 10% alfalfa meal or other green material
- 45 – 50 % fresh grass clippings or other fresh plant material (includes fresh fruit)
- 40 – 50% brown leaves and small wood chips
Bacterial dominated compost contains a higher percentage of green organic matter, higher in nitrogen, N (a lower C:N ratio). Grass clippings, fresh picked leaves, kitchen scraps, fresh cut foliage, fruit, vegetables and manures. A simple recipe, out of many variations, for bacterial dominated compost would be:
- 25% alfalfa meal or other green material
- 50% grass clippings
- 25% brown leaves, wood or bark chips
Compost production is a time-honored tradition with a few modern day upgrades. Although compost will happen regardless, to facilitate the process, quicker composting requires heat, air, water, and organic materials with the right amounts of nitrogen and carbon.
- The compost pile can be in sun or shade.
- Carbon:Nitrogen ratio should be 25:1 to 30:1.
- It is not necessary to add nitrogen fertilizer or other commercial starters to the compost pile.
- Inoculation with soil or compost that contain microbes is helpful.
- The temperature must reach 150 degrees to kill weed seeds and most pathogens.
- If composting materials using the cooler, slower method, do not put weeds or manures containing weed seeds in the compost pile.
- Turning the pile aerates the pile, cools it and helps the pile to heat up. Turning the pile speeds up the process for a quicker end product.
- We don't have to worry about covering it in our climate. But if we ever experience an extended rainy period where the compost pile is in danger of becoming saturated, then cover before it reaches this point.
- During Panhandle summers, add water when turning the pile; compost piles in our climate dry out.
- Do not add human or pet feces because of the possibility of disease organisms that would survive the heat process. By the same token, be very careful of the types of other manures or materials added to the compost pile. Certain persistant herbicides, aminopyralid, clopyralid, fluroxypyr, picloram and triclopyr registered for use in pasture, grain crops, residential and commercial turf, roadsides, certain vegetables and fruits crops remain active in manures and plant matter even after decomposition, up to three years.
- Sawdust contains a high C:N ratio of 500:1, not ideal for making compost.
For a further discussion of compost, click on Composting under the Maintenance section or research the many other composting sites for exact, rapid procedures.
Other Plant Recycling
One more form of recycling with direct, immediate benefits is in using a mulching mower. Instead of going through the work of bagging the clippings and tending a compost pile, the use of a mulching mower returns the clippings to the soil surface where decomposition can begin immediately (with the presence of beneficial soil microbes). If you have a thatch buildup of more than half an inch, dethatch, aerate, and apply compost, granular humate and horticultural molasses to stimulate the decomposition process.
Recycle other plant debris in beds and borders in place after removal of any weed or other seed heads. Diseased plants should be discarded in the trash bin, not used on site. Fallen autumn leaves is like candy from the sky for plants. Landfills don't need them, our landscapes do. Mow to shred the larger leaves and mulch beds and borders, or mulch mow directly on the lawn. Shredded leaves can be bagged and saved for use in the spring if you have an abundance.
Larger stems and branches can be shredded for use as mulch or in the compost pile. Hugelkultur, the practice of mound gardening, buries branches, even tree trunks, in soil, layering green and brown materials with soil, moistening as it's layered, to create over time, fertile raised beds.
Composting is nature's way of restoring nutrients to the soil, perpetuating the cycle of life. Don't waste this precious natural resource.