Questions and Answers 2012

Bernalillo County Extension Master Composters

Here are some of the questions sent to the BCEMC email hotline in 2012. You can send your own questions to

Please keep in mind that composting is an art as well as a science. Different solutions work for different people and in different circumstances. Each composter must find his or her own way. Also, note that we are composting in the desert climate of Albuquerque, New Mexico, and nearby. If you are composting in a different climate, some answers might not apply to you.

Names and identifying information about questioners have been removed. Questions and answers have been edited to modify some formatting and correct typos in the original email. Apologies for awkward formatting and typos that remain.

Testing Compost for Pathogens

November 6, 2012


I am searching for someone who can test my compost for E. Coli and Salmonella before it goes into my vegetable garden. Is this something you can help me with?

Answer by JE:

I've been giving your email a lot of thought and I would refer you to environmental labs if your feel this is what you want to do compost testing. Just look under laboratories/environmental in the yellow pages or you can contact Universities that have an agricultural department such as NMSU. However, I feel an obligation to provide you with some further advice before you go through the expense of testing the soil. First you should ask yourself why you want to test for these organisms. Did you have some sort of contamination that you are worried about?

  • Testing soil is very tricky and can be expensive. First you need to consider how are you going to sample it to make sure you get a true sample and not just a pocket. A good lab will provide you will detailed instructions. When I worked as a microbiologist, we would always say the test in only as good as the sample. If you don't sample and transport it correctly the results are worthless.

  • E. Coli is a huge family of bacteria and not all E. Coli is pathogenic (disease causing). All mammals have E. Coli in our GI system as they provide us vitamins and have other essential roles. They are a part of the "natural flora" of our GI system. Also E. Coli can be found in almost all dirt samples. If I tested a 100 shoes for E. Coli I bet everyone will be positive but very few will be shiga-toxin producing (this one cause the most trouble in GI problems) As an aside, E. Coli is the number one organism in urinary tract infections but are usually from the person's own GI tract not from other sources.

  • Salmonella is a water loving organism so you can save yourself a lot of money from testing by just letting your compost dry out completely for several months.

  • Also if you are doing hot composting, any pathogens present will be destroyed by the heat. Pathogens do best at body temperature and will die above 120 degrees F. In addition, most pathogens can't stand UV light so if you are in a place with lot of sun light it will also destroy pathogens.

If you have further questions, please feel free to email me back.

Can Worms Decontaminate the Soil?

October 15, 2012


I'm a 12 year old girl in the 7th grade. for my Science Fair I am going to conduct a science experiment on composting with red wiggler worms. I am going to see if they will decontaminate soil that has been soaked with a contaminant. Please tell me if the following would harm the worms; used motor oil, used canola oil.

Answer by JZ:

You have selected an interesting project! I'll suggest that it might be OK to use used canola oil, but not motor oil with worms. That said, in the interest of science you might try the motor oil with a very small batch of worms and see if they survive the environment, then proceed from that result. For motor oil you might consider using fungal and/or bacterial cultures for decontamination.

Answer by PB:

You might want to rethink your idea of using worms. Worms have no lungs and breathe through their skin. Oil clogs their pores and they will suffocate. We never advise putting oil cooked foods in a worm compost bin for this reason - even potato chips can be deadly to them. Therefore, trying to use them to decontaminate oil would not give her the result she is looking for as they would not survive long enough to prove or disprove her hypothesis.

Where to Place a Composter

October 9, 2012


I'm a new county resident and I'm looking for the best location in my Sandia Park (Sandia Knolls) yard to place my composter. Are there any rules out here that dictate distance between a composter and lot lines or standing structures (or any other rules)? I'm planning to use a wood box rather than a plastic thing or an uncovered pile.

Answer by PB:

Not familiar with Bernalillo County/ABQ. Just know that there are easements that need to be respected as far as the construction of permanent structures - in Rio Rancho it is 5 feet. Some HOA's also have regulations for permanent structures. I would just caution you to be respectful of your neighbors as far as smells and the potential for pests. Also it should be near a water source and kept covered.

Roaches in the Compost

August 17, 2012


I live in Albuquerque. I got your email from the City of Albuquerque's link on "Ask a Master" in their composting section. I'm sure you've had people asking you about this problem, but I just need to know what would be the best steps. We have a composting pile that is well established in our backyard into its third year (using the soil once it's become rich, of course). It's in the back corner of our back yard but not far from our house maybe 50-60ft. I will admit the compost has been neglected recently as far as watering and turning it. So when I was watering all the gardens today I decided I needed to tend to the compost. I watered it down to give it some moisture and then started to turn it. Just under our recent fruit/veg scraps looked to be hundreds of small roaches about 1 in long reddish orange looking and almost still translucent looking. I suspect they are roaches because they look like roaches and move fast like roaches. I hate roaches, and my main concern is if I deter them from their current habitat, I don't want them coming into our house. They can't really get any further from the house, but maybe ten feet back. I've read on some websites to first get them the furthest from you house as you can, but in this case I wouldn't want to just move them 10-15 feet back would I? Or I could move it more lateral across the yard, it would be further from the doors/windows, but not really any further from the house. I have read some info online, but what would you recommend being my best option at this time?

Answer by WR:

Yep, sounds like roaches. They give me the creeps, too. I've been told (and have observed) that roaches don't like to be disturbed so if you turn the compost fairly often, they'll stay away from it to some extent. I'll still see them occasionally but not in huge numbers, unless, as you experienced, I haven't turned it in a while.

As far as them coming into your house, it's good that you are maximizing distance from the house as much as practical. However, there are so many roaches in ABQ just on the streets, in our yards, in the water mains, etc. I'm not sure that the ones in the compost have a huge impact on what goes in your home. Last year I bought a little mini-greenhouse (about 2 x 4 feet) from someone on Craig's List. It had rocks in the bottom for drainage. I decided to clean it out and started dumping out the rocks, and, to my horror, they were teaming with literally hundreds (thousands?) of cockroaches. This was on my patio right next to my house. I, of course, thought, oh no, my house is going to be filled with these roaches. But, the amazing thing was, I didn't end up seeing any roaches in my house from that. Since you disturbed all those roaches in your compost, have you noticed more roaches in your house? For some reason that I don't understand, I've seen fewer roaches in my house the past couple of years. I'm wondering if the city is doing something?? If I start seeing more than one or two in my house, I put out borax in shallow plastic lids (like cottage cheese lids) and tuck them out of the way such as under the refrigerator, stove, washing machine, bathroom shelf. This does seem to help.

I'm going to copy this response to the folks who answer and see if they have more to add. It's great that you haven't let the roaches deter you from composting! Thanks for writing and please write back or call if you'd like to discuss this further.

Answer by WR, Addendum:

PS. From what you read on-line, you probably read that if you can stand the creep factor, roaches are beneficial in the compost, helping break down the materials in the compost. But, then if you turn it frequently you won't have as many hanging around. But, it is better to turn at least occasionally. That's even more beneficial to the compost. I know your big concern is turning it and driving the roaches into your house. I'd be interested to know if you have noticed more roaches coming into your house since you turned it. If you are, let's talk about other approaches!

Stinky Compost Pile

August 14, 2012


Recently, a woman called me at the Valencia County Environmental Health Department to complain that her neighbor's compost pile stinks. I'm a NM Compost Facility Operator, so naturally I want to head to her neighbor's house and go play in the pile to make it work! Of course, I'm with the government (and not in Code Enforcement), so I can't do that. Are you guys in any position to help out in this situation? In what ways could we collaborate for future compost promotion and improvement?

Answer by JZ:

Thanks for your inquiry. I'm copying to one of our masters who lives in Bosque Farms and may be able to consult with you on the situation.

Some people smell with their eyes! Some composting is unpleasantly fragrant when an operation goes anaerobic and produces methane and hydrogen sulfide gases. This may be related to inadequate aeration due to compaction and/or increased amounts of nitrogenous material which is moist and easily compacts. The question is is the "offending" home owner open to advice on the situation? One would have to contact that person to find out, then go from there.

The Bernco Master Composter group is always available to you for consultation and teaching:

  • We could present a basic home composting class (s) in your community in the future- free/open to the public.

  • We could encourage Kyle Tater, the Valencia Co. horticultural agent to identify/encourage some from the community to take our master composter training in the future, so that you would have help locally.

I will follow up our Valencia Master Composter then get back to you. Let me know if this is helpful to you so far.

Composting Fruit Pits

July 5, 2012


Can apricot and cherry pits be composted? I bought a compost bin and have been saving vegetable and fruit scraps along with coffee and tea grinds, but wasn't sure whether to throw in the pits of fruit. I'll hold off on throwing the pits into my pile until I hear from you.

Answer by WR:

I throw my apricot and cherry pits into my compost. They do take quite a while to decompose, but they will eventually break down, especially in compost that doesn't get hot (like mine). What I do is, after the compost is finished, I put it through a screen (with about 1/4 inch mesh). This will take out the pits, twigs, avocado peels, etc. that haven't broken down completely. Just throw those back in to the next batch of working compost. If you don't want to bother to screen your compost, you might want to avoid putting the pits into the compost or hand-pick-out the worst offenders. They won't really hurt anything but will end up in your garden or wherever you use the compost. Or, I guess you can soak/boil your pits and grind them. I've never tried this but, hmm, might be interesting: You might want to do a Google search for "screening compost" (without the quotes) to see some pictures, etc. about that. I liked this page:

Your compost is "finished" when it smells good, the original stuff is unrecognizable (except the big woody things you'll be removing), is completely cool, and looks like rich crumbly earth. If it still has any sliminess, smells, etc. it should work a little longer.

It sounds like your compost is rich in nitrogen-rich things: food scraps, coffee, tea. If it starts smelling bad or is slimy you might want to balance it with carbon-rich things such as dry leaves. I think the seed pits are carbon rich, but they might not be enough to balance it, especially since they take so long. I'll attach a flyer that lists nitrogen vs. carbon things to compost.

Maggots in the Compost

June 24, 2012


We just discovered maggots or black fly larvae in our compost pile and initial research says that's a good thing. We only use kitchen veg and fruit scraps, no meat, dairy or oily foods. My question is, can we use this compost on our veg garden? Do we want to be distributing BFL into veg that we will be eating?

Answer by WR:

If you have a good hot compost and stir it up good, the maggots, or their "remains" should just compost along with everything else. Just more good organic material. Same is true for cold compost, but will be a little slower and they'll probably turn into flies or something at some point, just as they would if they laid their eggs elsewhere. You could try scooping them out, but they are not hurting anything. I wouldn't worry about the finished compost in your vegetable garden. Just, as always, be sure that you use compost that is "done" and and smells good like finished compost should. I remember the first time I saw maggots in my pile I was quite concerned and creeped out, too. That was quite a few years ago and I've since come to learn that, while I don't particularly welcome them, they aren't a problem. Good luck and be sure to write back if you have any other questions.

Answer by GM:

Fly larvae are definitely ok in your compost pile. Sounds like it is healthy. You may also find some other "disturbing" insects, just be assured that your friendly bugs are doing the business of decomposition. If you feel very uncomfortable with the larvae, your option might be to purchase a bin type of composter which would eliminate the pesky problem. However, you needn't worry about the fly larvae contaminating anything and they won't bother your veggies. The flies that are produced are usually very slow and if you want, some yellow sticky fly paper seems to work for me. I get it at the feed store or at a hardware store. By the time you start to use the compost, the larvae should be gone. Your compost is going through a process and the fly larvae are pretty much normal. I know, ick. And I don't use meat/dairy or oil either. If you would like to learn more about the decomp process, please go to to see the current class schedule. You are welcome at any of these events and there is no fee. If you have any other questions, please feel free to write us back.

C:N Ratio and Keeping Compost Moist in Our Climate

June 16, 2012


We are just starting to compost and I was wondering if in the southwest do we still use a 20/1 ratio of brown to green? And should we have an enclosed composter or will a fenced area work? My concern is the pile drying out.

Answer by WR:

I think most recommend 25:1 or 30:1. But 20:1 or 40:1 also work. It's hard to be exact anyway. I'm not an expert on the C:N ratio but checked the numbers with slides on this page on our website: I'm not sure, but I don't think the C:N numbers in the southwest are particularly different than other parts of the country. Of course, keeping compost moist is a big issue here in the southwest and an enclosed composter helps with that. But most of the composters I know here in Albuquerque use fence-type bins and often keep them covered with a lid or blanket or tarp. Check out some of the pictures on this page: If you can put your bin in the shade that really helps. I compost without a bin. I'm lucky to have a shady spot in the corner of my big back yard, away from the house. During the summer, I do water it a bit nearly every day with the garden hose. It's part of my morning routine in the garden. That seems sufficient to keep it moist. Of course, it would be better if I covered it, but since the pile is visible from my house, I wouldn't want to look at an old rug or some such. I do enjoy seeing the pile. This is a recent picture of it: I had lots of red worms appear in my pile many years ago and at some point I added a few more. So, I'm doing a combination vermicompost and regular cold compost, I guess. It seems to work well. The worms seem happy and I get great compost. It's great to hear you are starting to compost. I hope you enjoy it as much as I have. Please don't hesitate to send more questions.

Answer by WR, Addendum:

I just reread your question and see you asked about ratio of browns to greens (vs carbon to nitrogen). The ratio of browns to greens would depend on how much carbon or nitrogen are in the actual material you are using. Be sure to check out Omar's slides. The 9th slide talks about mixing greens and browns. But please don't worry too much about these ratios. If it starts smelling bad, you probably have too many greens (or need to turn the pile). If it's just sitting there not changing into compost, you probably have too many browns (or are not watering and turning often enough). I find that if I just throw in what I have available it works well nearly all the time.

Answer by JZ:

I think that WR has answered your questions. You are very welcome to attend one of our classes which are open/free to the public. See this link:

Nitrogen in City Compost

April 8, 2012


Does anyone know about the nitrogen content of the free compost at the city recycling center? I would like to use it in my tomato garden, but I am afraid it could inhibit fruit production. Any ideas?

Answer by JZ:

Best to contact the person who oversees the composting operation for the city. Most finished compost has an NPK of about 1:1:1.

Putting Moldy Food into Compost

March 13, 2012

Question from a Master Composter:

I have a friend who recently bought a compost bin, the kind that rotates. She said the people who sold it to her said not to put moldy food into it because it would introduce bad bacteria. I've certainly never heard of such a thing. (For one thing, isn't mold a fungus, not a bacteria?) It seems like moldy food in your frig just has a head start in the composting process, and I wouldn't hesitate to compost my own moldy food. Any thoughts about this? Was she given bad advice or am I wrong about this?

Answer by JE:

Mold is a fungus and not bacteria. However, if something smells bad, then it is probably from anaerobic bacteria. The bacteria that spoil food don't make us sick as much as they gross us out. Most of the bacterial food pathogens don't smell at all! The deceptive little buggers. I agree that putting spoiled food into any compost pile means the microbes are already getting started at the process.

Answer by PB:

I agree with this too. Just spoke to a group this morning and the subject of mold came up. I have them basically the information WR and JE have stated below.

Response from Original Questioner:

Yes, thanks a lot JE and PB for your thoughts. I did a google search for "don't put moldy food in compost" (without the quotes) and most that came say it's fine to compost moldy food. The one person I found who said not to compost moldy bread also said to not compost bread at all as it "adds nothing to the compost heap". Of course, I don't agree with that at all, so don't consider that person to be a credible source. A major reason to compost is to keep organic waste out of the landfill. Also, bread contributes plenty of organic matter to the pile, per volume. The only reason I wouldn't compost bread would be if I were concerned about dogs or other large animals eating it. Which wouldn't be a problem in a tumbler bin.

Also See Questions from Other Years