Tips for Using Composting Tumbler Bins in the Desert
Bernalillo County Extension Master Composters
Created: August 2016
Modified: July 2019
Tumbler bins are holding containers for compostable materials which help manage air, moisture and often prevent unwanted critters from disturbing what is inside. How any bin is managed will determine the outcome. Compostable materials in a bin require moisture, air, appropriate temperature, and time for decomposition to occur.
For about ninety years composters have been taught that turning a composting setup was useful for aeration and blending of ingredients to assure timely completion of the decomposition process. This concept was taught almost obsessively and continues today.
Close to fifty years ago someone took the turning concept and invented a revolving composting container. Easy turning provided easier blending of the bin organics. Advertising hyperbole followed the manufacture and sale of tumbler bins, giving them an almost magical effect on the decomposition process. Advertisements touted "Superior Compost in 14 Days!" This expectation persists, but without substantiation.
Research, composting practice, and observation have revealed that decomposition occurs without turning organic material as long as air and moisture are maintained throughout the decomposition process. Static, no turn decomposition mimics the natural decomposition process which occurs on a moist forest floor and anywhere where those moist conditions are duplicated and maintained. Properly practiced, static composting is a useful valid technique. For a useful resource about compost turning see Jenkins, Joseph, 2005, The Humanure Handbook, pages 48-52.
Obtaining a tumbler composting bin:
Both homemade and manufactured composting bins are available in many styles. You may view a variety of products on-line. Amazon.com has many bins with useful pictures and descriptions. A new, high-quality manufactured tumbler bin will cost $100.00 or more. Used bins might be found at yard sales, thrift stores, eBay.com, craigslist.org, and freecycle.org.
Some considerations before you obtain a tumbler bin:
- What style and color appeals to you?
- How much are you willing to pay for a bin?
- Do you have a convenient space in your yard with a nearby water source?
- Is there a shady location for the bin in the summer months?
- A bin with wheels, making it easy to move, is a very useful feature.
- A small bin is easier to turn than a large one. If you have physical limitations then start with a small tumbler bin, such as 15 to 50 gallons.
- As a rough guide, a 35 gallon bin suits an urban homestead of one to four persons.
- A tumbler bin elevated above the soil provides easy access without having to bend over to make an addition and minimizes access by insects and mice.
- Do you know someone who already has an operational tumbler bin? What is their experience with that style bin?
- A used bin would be an inexpensive way to start.
- You may make/customize your own tumbler bin from a trash can or barrel. Plans for such bins may be found on-line.
Suggestions for tumbler bin use in the desert:
- Bin placement: Place the bin in the shade for the summer months because high temperatures and high ultraviolet radiation will encourage evaporation of moisture from the contents. If no shade is available, then drape two layers of shade fabric over the entire bin. Hold the fabric in place with clamps or bricks.
- Drainage holes: Water drainage holes must remain open at all times. To determine where the drain holes are in any particular bin, add one gallon of water to the bin and notice from where the water drains out. Those are your drain holes. Avoid allowing liquid to stand in a bin as that will create an anaerobic (low oxygen) situation which may become odiferous.
Methods for adding materials to the bin:
How you add materials is the choice of the individual backyard composter. Both of these methods will produce a high-quality finished product:
- Dump and Run: Add organic materials whenever they become available. Adding materials occasionally and continuously is often a convenient choice for home composters. This method usually results in cold process composting, which works very well. See more details in next section.
- Batch Method: Fill the bin about 3/4 full with a blend of greens and browns all at one time. (Details below.) There should be space in the bin for movement when it is turned. Ideally the added blend should contain two parts browns mixed with one part greens. This method may be used for hot process composting in a large volume tumbler which holds 70 to 170 gallons.
- Cold Process, Active Management: This involves the occasional addition of whatever organics may be available: dump and tumble. This process is an easy choice for many backyard composters. Add whatever organics you have at any time. Mixing green with browns improves the process. Soak dry material before adding. Chop, shred, rip materials before adding, because smaller decomposes better. Sprinkle in a handful of coarse bulking material with each addition: finger size sticks, twigs, pine needles and cones. Bulking improves air flow and prevents compaction of wet ingredients which may cause odors. Maintain moisture at 50% at all times. This level may be compared to the residual moisture level in brewed coffee grounds or a wrung-out sponge. Then tumble gently a few times to mix in the new materials. This process will be impacted by seasonal temperature changes. Colder is slower, warmer is faster. Because of seasonal temperature impact one should expect anywhere from a six to twelve month decomposition cycle. For more information see Cold Process in our Composting in the Desert Brochure, page 5. Note that bins using the active cold process will present a confused picture inside the bin, as undecomposed material is continuously blended with already decomposed material. Harvesting and sifting small amounts from the bin regularly every three months will help clarify confusion: sift out the finished compost (it will looks like coffee grounds) and return the undecomposed material to the bin and continue the process. See 10 below.
- Cold Process, Static Management: Both research and practice have modified the thinking that a composting setup needs to be turned. Organic material in a tumbler bin will decompose without turning as long as coarse materials are added to keep the organics fluffy and moisture is maintained at 50% at all times. Static/no turn composting is reliable and quite easy to do. The choice to tumble or to use a bin statically is up to the individual. You could try both methods, individually, for a time, then see what suits you.
- Hot Process: Most often, sustained, appreciable heat will result when a batch method is used (see 5b above). The heat generated will be sustained as it is insulated by the total mass within the bin. Therefore, large volume tumblers are useful for this method: 70 to 170 gallons. With proper management, this is a three to six month process. For more information, see Hot Process in our Composting in the Desert Brochure, page 3.
Moisture in the bin:
- All organics in the bin should maintain saturation with 50% water. This moisture level may be compared to the residual moisture content of brewed coffee grounds or a squeezed-out sponge.
- Water may be sprinkled on the ingredients as necessary to maintain 50% moisture at all times.
- Dry materials may be soaked in water before being added to a bin.
- Chopping, shredding, cutting, or ripping material before adding increases the surface area, which then allows for better water penetration of the material.
- Ideally the bin should be in the shade in summer months to decrease evaporation of moisture.
Adding compostable organic material to the bin:
- See our Composting in the Desert Brochure, page 3, for a list of green and brown compostable materials and those which should be left out.
- Gather ten gallons of coarse bulking material and store it near the bin. For example, finger size sticks, twigs, pine cones, pine needles, and corn cobs. Bulking material will help decrease compaction of other moist organics in the bin, decrease clump formation, and improve convective air flow in the bin. Regular bulking allows for both static and active tumbling situations. Each time you add organic material also add some bulking material on top, then gently tumble to mix the ingredients. Rough guide: for every gallon of organics added, sprinkle in about 2 handfuls of coarse bulking material.
- Except for bulking material, chop, shred, cut, rip or grind all material before adding to the bin. Smaller organics absorb water better and decompose faster.
- Dry materials such as paper products and cardboard may be soaked in water before adding.
- Avoid compacting and over-stuffing a bin as the contents will then not mix well. 3/4 full is enough. As decomposition occurs the materials in the bin will sink down, making space for more material to be added. Simply distribute new materials on top of the existing content, then tumble gently.
- Check the moisture level when first opening the bin. If necessary sprinkle with water as needed. Excess water will escape by way of the drain holes. Maintain 50% moisture of the bin contents at all times.
- Over-exuberant tumbling is not required. Just tumble to blend in what you have just added. (As noted above, tumbling is optional.)
Tumbling the bin:
- Follow manufacturer's suggestions, if you have them. There are various opinions on tumbling frequency, no hard and fast rules. With practice you will develop your own expertise with your bin.
- If bin contents are dry, before adding new materials, sprinkle with water and tumble. Continue sprinkling and tumbling till all ingredients are moist.
- Add your organic material, sprinkle in coarse bulking, then tumble gently until blended.
- If bin contents are too moist, then add dry material such as shredded brown leaves or paper products, then tumble to blend in.
- Tumbler bins may be used statically (i.e., not tumbled) as long as you regularly add bulking material with each addition and maintain 50% moisture in the contents.
Harvesting finished compost from the bin:
- Spread a tarp under the bin opening, then tilt the opening over the tarp. Dump and scoop out some of the bin contents onto 1/4" to 1/2" hardware cloth placed over an empty wheel barrow. Sift out and remove any undecomposed material, e.g., bulking, which will go back into the bin for further decomposition. The finished compost may then be stored or added to garden soil.
- Dump and run tumbler contents present a confused picture to the novice because you are constantly adding undecomposed material to that which is already decomposed, so everything is mixed together. You may clarify the picture by harvesting regularly, e.g., every 3 months. Finished compost looks like coffee grounds or chocolate cake crumbs.
- In the summer season, batch method bins will have some finished compost within about 3 months. Timing varies. Harvesting the batch is the same method as described above.
- Small balls (clumps) of wet organic material are forming in my bin and they have an unpleasant odor. What to do? Break up any formed balls, then sprinkle in some coarse bulking material and blend. Avoid future over-exuberant tumbling. Continue to bulk as you add other organics.
- My bin is full. What to do now? Maintain moisture and allow decomposition to continue. Harvest from the bin to remove finished compost. Obtain an additional bin or set up another composting method. Extra browns may be stored for later use.
- My bin is too heavy to turn. Allow decomposition to happen statically; no turning is necessary. Maintain 50% moisture at all times.
- Nothing is happening in my bin. What should I do? If you are maintaining moisture, decomposition will proceed. Harvest from the bin to get a better idea of what is actually happening. See 10 above.
Where to learn more and get help:
- Attend one of our free Composting in Tumbler Bins classes. Visit Bernalillo County Master Composters: Classes/Activities for the Public to see when one will be offered.
- Email us your composting questions: firstname.lastname@example.org. Please include your residential zip code in your email.