Composting in an Arid Environment

Why should I compost?

Composting is a great way to reduce the waste created in the home and utilize it instead of sending it to a landfill.  The product of composting is an excellent nutrient-rich material that can be used to fertilize gardens and trees- improving productivity and quality in your garden while saving you money on fertilizer.

A garden that is fertilized with composted materials can better hold oxygen and water, drain more efficiently, and produce plants with fewer insect and disease problems.  Composted humus promotes the growth of beneficial microorganisms in soil, and discourages harmful ones.

Different composting methods have been developed to best meet environmental conditions (eg: humid/tropical, dry/arid). Special considerations, which are described below, need to be made to compost effectively in arid environments where a lack of ambient humidity may desiccate organic matter before it has time to decompose.

Can I compost?

An assessment should be made before settig up a compost pile, to determine if composting is even a possibility. Reducing waste is one reason why people compost, however, most people compost in order to create fertilizer that improves garden productivity. The main considerations for composting in an arid environment are 1) time, 2) effort, 3) sufficient water. As shown below, the no-tending method require very little time, but the composter may encounter difficulties if the pile is not given any attention (see Troubleshooting below). If that is the case, the composter must determine if the payoff is worth the time needed to tend the pile. If the pile is tended, some effort is required. It is understood that many people are busy with work and other household chores and mixing a composting pile may not be a priority. Thus, if the no-tending composting pile does not work, then, once again, the user must weigh effort versus payoff and decide if composting is appropriate. The third consideration, having sufficient water, is important in an arid environment. Obviously, it is not going to be appropriate to compost if water is needed, yet scarce. Keep in mind, however, that dirty water from the kitchen (dishwater, for example) and urea can be used.

 How does it work?

Composting is the process of breaking down and decomposing organic matter.  Microorganisms in the pile feed on the material that you put into the compost, and in return give off CO2, water, heat and humus.  Humus is the stable organic end product that holds the nutrients that can then be used in your garden.

The microorganisms that do the composting work are bacteria and fungi.  The fungi break down the tougher debris in the compost pile, allowing the bacteria to continue decomposing the broken down material. 

These microorganisms in your pile survive on the organic ingredients or your compost, but they need certain conditions to survive and work most efficiently.  Moisture is an important element; compostpiles should contain 40-55% moisture, like a wrung out wet sponge.  Too little moisture desiccates the microorganisms, and too much drowns them.  Temperature is anther important aspect too.  Though there is a range of temperatures that all the different organisms thrive at, the pile should not reach above 65°.  Temperatures below 55° don’t kill the pathogens that are unsanitary to humans, but lower temperature composting is effective also, it just takes longer. 

The bacteria live on the contents of the pile, but the actual active “feed” is the carbon and nitrogen that is contained in the organic matter, along with the oxygen necessary for aeration.  This is what the microorganisms use to decompose the compost.  The ideal mixture for your compost pile is to have a 30:1 ratio for C:N, but this does not need to be a precise measurement, and can be judged on the heat and smell of your compost- see below under How do I maintain it?

What can I compost?

Composting is a great way to deal with food scraps, yard waste, and animal manure.  These things are all great additions to a successful compost pile, and add different nutrients to the mix.  Most kitchen waste is great to throw in, including fruit and vegetable scraps, egg shells, coffee grounds and filters, graywater, corn cobs and more. Kitchen waste is usually high in moisture, which makes it and important component in aird-environment composting.  Dairy products can be composted, but should be buried in the pile to avoid the smell that they generate, which may attract animals.  Fatty foods like meat and oils should not go in your compost pile.

Not acceptable
Eggshells Bones
Coffee grounds
Fruit scraps
Vegetable scraps
Corncobs Dog and cat feces
Leaf litter/branches
Breads and grains
Graywater Dairy products
Fire ashes

Cattle manure

Where should I compost?

Your compost pile should be located in a level, well drained area with ample shade to protect it from the sun. This will help it retain moisture - a potential problem in arid environments. Put the pile close enough to the kitchen, so that it will be convenient and used regularly.

What do I need? 

The equipment for simple composting is minimal and based primarily on how you choose to compost. Throwing compost into an easily accessible pile is the lowest maintenance option. In that case, the only tools necessary are a shovel or stiff-tined fork for turning and removing compost. To ward off unwanted pests (animals, large birds) it is a good idea to protect it using some type of fence. Alternatively, you could build a wire-mesh box, which not only protects it from animals, but makes it easier to move around when full. The drawback to confining it is that then the compost does not have contact with the soil, which provides microbes, worms and bacteria to speed up the process.

How do I maintain it?

One method of composting entails throwing organic matter into a wire mesh box, and is classified as a “hot and fast” method that will produce compost from a cubic meter pile within a few months. It does require it turned several times a week, which is done by mixing it with a stick or shovel. As turning does lead to dehydration, and thus slowing of the decomposing process, in arid environments, monitor the effects of pile intervention. If the compost is drying up, a passive approach can be taken, though composting time is much longer (up to a year). The decision is based on 1) how much waste is produced and needs to be managed 2) environmental conditions (ie: humidity) 3) quantity of compost needed and 4) the eagerness of the composter.

Regardless of whether an active or passive approach is adopted, the compost should be checked for moisture periodically, important in arid regions. As mentioned, it should be as moist as a wrung-out sponge. If necessary, add water to maintain the appropriate moisture level. In particularly parched areas, using dirty dishwater or adding urea are effective water-saving options.

Compost with lots of kitchen scraps does have the potential to attract flies and animals. The box method, as mentioned, should discourage animals. To ward off flies and insects, be sure to cover new organic matter with about 8 inches of old compost. 

Troubleshooting - here's the shortlist of common problems. Click here for more in-depth information.

Symptom Cause
Fix it
Bad odor
Poorly aerated
Turn it
Not enough moisture
Add water
Nothing is happening
Not enough nitrogen
Not enough oxygen
Not enough water
Add manure
Turn it
Add water
Ammonia odor
Not enough carbon
Add leaves


Where can I apply compost and when?

The organic matter is thoroughly decomposed and ready for placement when the material is brown, crumbly, and earthy-smelling. If it is not fully broken down (material is still somewhat recognizable), then it should be allowed to further decompose, or be separated out.

The humus can be used on vegetable gardens and trees. If little organic matter is present in the native soils, a two to three inch layer of compost should be worked into the top six inches of soil. Following the first year, only ½ inch of compost is necessary to maintain soil quality.

For information on other methods (windrow, closed bin, artificial aeration, etc.) and more information, here are more resources:

On-farm composting methods   - Numerous alternate methods and specific case studies presented. Florida’s online composting center - Check out their 6 question quiz to help you decide what method is best for you.
Cornell University  - Easy-to-read brochure on composting, with specific information on mulching, soil incorporation and earthworm compost. Waste stoppers-  Quick look at composting from the Gould League of Victoria in Australia.
US Army Center for Health Promotion and Preventive Medicine (USACHPPM)  - A comprehensive overview of different methods (expensive and high tech). Some case studies. Nebguide (University of Nebraska) - Bin composting method described by the Institute of Agriculture and Natural Resources at U of N.
Ohio State University  - In-depth information, covers the use of additives (lime, ash, phosphate) to improve composting  and decomposition rates.
Compost Guide - Though this is a site set up to sell composting bins and supplies, the information that it offers it is a good resource for composters.
Natural gardening and composting - Brief composting overview.
Xavier University of Agriculture, Philippines - Comprehensive study, various  methods and advantages and disadvantages of each listed.
Compost web resources - An overview of resources available on-line.
Master Composter - In depth information, includes a message board.

        Composting Literature

Campbel, 1998, Let it Rot!: The Gardner's Guide to Composting (third edition), Storey Communications, Inc.
Dickson, Composting to Reduce the Waste Stream: A Guide to Small Scale Food and Yard Waste   Composting, NRAES-43, Natural, Resource, Agriculture, and Engineering Service (buy it at NRES ).
Gershuny and Martin (editors), 1992, The Rodale Book of Composting: Easy Methods for Every Gardener, Rodale Press, Inc.
Taylor, Taylor and McCosker, 1994, The Compost Book, Robert Hale Ltd
Vance, 2001, Backyard composting: Simple, small-scale methods, Cooperative Extension Service, University of Wyoming; [Rev. ed.] edition

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This webpage was compiled and designed by Ellen Engberg and Essa Gross for FW 5770,  March 16, 2005.
Updated April 13, 2005.
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