Keeping Green Landscapers Guide

Composting

On Site
Off Site
Checklist

On Site

What Is Composting and Why Do It?  Composting, nature’s own way of recycling, is the controlled decomposition of organic material such as leaves, twigs, grass clippings, and vegetable food waste. Compost is the soil amendment product that results from proper composting. Whether it’s done on site, at the point of waste generation, or in a large scale, centralized facility, composting helps to keep the high volume of organic material out of landfills and turns it into a useful product. Onsite composting reduces the cost of hauling materials and is generally exempted from solid waste regulations. Large scale facilities can handle more material and potentially produce a more consistent product, but may be faced with regulatory issues. 

The following sections provide information to get you started composting at any scale. The principles of composting are the same if you have one cubic yard or many hundreds. Recent regulatory developments may allow landscapers to process materials they generate without excessive state-level, solid waste regulatory burden as discussed under the offsite section. However, since composting involves the decay of organic wastes, people who choose to compost need to be sensitive to the impacts their operations could have on others. Noise, dust, and odor are common complaints about poorly run operations. It’s best to be as good a neighbor as possible, to insure minimal impacts. 

However you go about doing it, composting can be very cost effective, and compost is great for your gardens and landscaping, saving money spent on purchasing soil conditioners, mulch, and fertilizer.

Composting—Small and Easy 
Composting can be done in most backyards in a homemade or manufactured composting bin or an open pile (some cities do require enclosed bins). Businesses, schools, and other facilities with adequate yard area can also easily compost. Professional landscapers should consider offering the service of maintaining a compost bin or pile for their clients. This could save trips to the dump, and produce compost for use at that account. 

Consider contacting your city or county government for information about free composting workshops and discounted composting bins. You can obtain many ready-to-use bins through retail or mail-order establishments. Even an old garbage can may be used for composting if you punch holes in the sides and bottom. For a description of how to build your own bin or a list of manufactured home composting bins, call the California Integrated Waste Management Board at (800) CA-WASTE or visit our online ompost bin shopping guide.

Recipe for Composting 
While a multitude of organisms, fungus, and bacteria are involved in the overall process, there are four basic ingredients for composting: nitrogen, carbon, water and air. Composting is a lot like cooking, and the easiest compost recipe calls for blending roughly equal parts of green or wet material (which is high in nitrogen) and brown or dry material (which is high in carbon). Simply layer or mix these materials in a pile or enclosure; chop or shred large pieces to 12" or shorter. Water and fluff to add air. Then leave it to the microorganisms which will break down the material over time.

Nitrogen. Grass clippings, landscape trimmings, and green garden waste are ideal sources of nitrogen for composting. Vegetable and fruit trimmings and peels can also provide nitrogen. To reduce the potential for pests or odors, it is best to avoid meat or dairy scraps and bury any food scraps deep within the compost pile.

Carbon. Dry yard and garden material such as dry leaves, twigs, or hay can provide the carbon balance for a compost pile. Untreated wood chips and sawdust are a powerful carbon source which may be useful if the pile contains excess nitrogen.

Water.  One of the most common mistakes in composting is letting the pile get too dry. Your compost pile should be moist as a wrung-out sponge. A moisture content of 40 to 60 percent is preferable. To test for adequate moisture, reach into your compost pile and grab a handful of material and squeeze it; if a few drops of water come out, it’s probably got enough moisture, if it doesn’t, add water. When you water, it is best to put a hose into the pile so that you aren’t just wetting the top. You can also water as you are turning the pile. During dry weather, you may have to add water regularly. A properly constructed compost pile will drain excess water and not become soggy.

Air. The bacteria and fungus that are in your compost pile need oxygen to live and work. If your pile is too dense or becomes too wet, the air supply to the inside is cut off and the beneficial organisms die. Decomposition will slow and an offensive odor may arise. To avoid this and speed the process, turn and fluff the pile with a pitchfork often, perhaps weekly. You can also turn the pile by just re-piling it into a new pile; many composting bins make this easy to do by coming apart so you can easily re-pile the old pile back into the bin. 

Time, Temperature, Style, and Size 
omposting can be done in a hot, fast, "gourmet" fashion by the active gardener or in a more casual manner. Both ways will have a positive effect on the environment and produce useable compost. It just depends on how much time you want to spend with your compost pile and how fast you want the compost.

"Gourmet" compost piles that have the right blend of nitrogen (greens) and carbon (browns) and are kept moist and fluffed regularly, will heat up to temperatures of 120 to 140 degrees Fahrenheit. These high temperatures will kill most weed seeds and speed up the process so that the "compost" could be ready in just a few months. 

"Casual" compost piles are also quite workable since compost will "happen" even if you just pile on yard and food waste, water sporadically, and wait. The pile won’t get as hot, so it won’t decompose as quickly and may not kill weed seeds. Casual composting can take more time.

Ideally, the compost pile should be at least three feet wide by three feet deep by three feet tall (one cubic yard). This size provides enough food and insulation to keep the organisms warm and happy and working hard. However, piles can be larger or smaller and work just fine if managed well.

How to tell when it’s done
Your compost is finished when the original material has been transformed into a uniform dark brown, crumbly product with a pleasant earthy aroma. There may be a few chunks of woody material left; these can be screened out and put back into a new pile.

You may want to stop adding to your compost pile after it gets to optimal size (see above) and start a new pile so that your first pile can finish decomposing (during which time the temperature will drop).

Composting is best learned while doing. Through practice and observation you will find what works best for your situation, and you can modify the process to suit your needs. There are also a number of books written on small scale composting; check your local library or bookstore. Also, remember to check with your local government for workshops, handouts, or guides on composting.

Off Site

Composting—Medium to Large
California law currently defines a composting facility as a solid waste facility. Until recently, that meant any composting activity of significance (i.e., larger than a backyard pile) required complicated permitting. New regulations have approached the issue of composting as an activity to encourage, and present a structure that allows medium-sized operations to site and operate with minimal solid waste permitting requirements. For more information, please refer to Composting Operations Regulatory Requirements.

Regulations
However, regardless of the recent reforms in compost regulations from a solid waste perspective, there are other environmental agencies that may also have requirements for composting operations, such as the Regional Water Quality Control Board, the Air Quality Management District, the local planning department, and even the local fire district. 

Information on how a composting activity of given size and feedstock fits into regulation, and what other licenses or permits are required, can be obtained by contacting your local enforcement agency (usually the county environmental health department) or the CIWMB’s Permitting and Enforcement division.

Equipment and Cost 
From a purely technical perspective, medium scale composting offers opportunities and efficiencies over smaller scale operations. However, while the fundamentals of composting remain the same whether it’s one cubic yard or 1000, certain management issues become more critical as volumes increase. Managing a small home compost pile requires little more than a pitchfork. However, managing many hundreds of cubic yards at a time may require some heavier equipment. Small motorized loaders with a front bucket or blade, sometimes called skip loaders, are useful tools for moving and lifting composting materials. Preprocessing larger trimmings will facilitate decomposition, so a chipper or grinder may be useful. In the end, screening the compost separates larger pieces from the finer compost and creates a higher quality product. The larger pieces can be returned to the composting process, or further refined and used as a mulch. 

Clearly, the larger the operation, the more expensive it becomes. However, larger piles will decompose more rapidly than small, and larger volumes produce a large quantity of consistent product. The marginal costs of production—the dollars spent per ton of material—generally decreases as an operation grows. Additionally, the avoided disposal costs and avoided soil amendment costs may justify the investment in equipment to manage large amounts of material.

Size and Temperature 
Caution, however, must be taken to avoid piling materials too high, or getting too hot. While a hot pile is desirable to kill weeds and pathogens, temperatures should be managed and kept below 150 degrees Fahrenheit to avoid destroying beneficial organisms and control fire danger. With the right combination of ingredients and weather conditions, the danger of spontaneous combustion is very real if compost piles are allowed to stack much over ten feet high. The heat from microbes consuming the composting material will build up through a "chimney" effect. Once temperatures reach approximately 170 degrees, the microbes are killed off, but a biochemical reaction takes over that can eventually result in flames. Nevertheless, the water vapor or steam released from an active, healthy compost pile should not be mistaken as fire. 

Perhaps your landscaping activities generate more trimmings than you are able to managed yourself or doing your own composting isn’t feasible. There are two good reasons to deliver materials to an organics recycler or composter instead of a landfill: (1) the "tipping fee" is usually less at a recycler’s operation than at disposal and (2) the recycler has a supply of soil amendments that your accounts can use. 

If your local government doesn’t know of one, the CIWMB can probably help you find an organics recycler who will process your trimmings, and also be a source of soil amendments for your landscaping projects (see reference section for contact number.)

Checklist 

Use this checklist to help you do your part by composting organic materials for yourself or your clients, or deliver your trimmings to a commercial organics recycler.

• Compost piles or bins are located in an area with easy access that is aesthetically acceptable.
• Compost "ingredients" are added and blended to balance the carbon and nitrogen ratios. The right mix is easy to do mixing equal parts "green" and "brown."
• The compost is kept sufficiently moist, like a wrung-out sponge, to keep the microbes happily decomposing.
• The compost pile is turned, fluffed, or otherwise "aerated" to provide oxygen to the microbe and prevent odor.
• The finished compost is used as a soil amendment or mulch to naturally return nutrients to the landscape and save money on amendment purchases.
• Diseased plant material and mature weeds with seeds should only be added to a "hot" pile to be sterilized.
• Larger-scale composting must be performed in a responsible, good-neighborly manner.
• State and local laws may require permitting or licensing of larger composting facilities.
• Take excess material to local, commercial-scale composters will likely accept clean landscape trimmings and sell quality organic soil amendment for landscaping uses.

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Last updated: April 22, 2008