Why Doesn't Super Hot Compost Starter Help Raise the Temperature in my Pile?

by Betty
(Birdsboro, Pa,)

My husband and I are new to the gardening and composting world. I'd saying we're doing fairly well with the gardening part, if you don't count the green bean episode where we couldn't tell the weeds from the beans so we had to start over and mark where the seeds were planted.

Now the compost is another story. I've read that most pathogens die at 131 degrees and a few at 140 degrees. Our problem is that the temperature has not risen above 110 degrees . We started the pile (about 1 month ago) with shredded newspaper, straw, about 9 lb. of coffee, lots of kitchen scraps, no meat,dairy, or oils and Super Hot Compost Starter. My husband stirs the pile once a day and started taking the temp about 2 weeks ago and it was 110 degrees and that's where it remains. We have added to the pile but we always add 3 parts brown to 1 part green. He added This Super Hot Compost Starter once more, it shot up to 120 degrees for less than a day. Help! what are we doing wrong?

Hot Composting and the Super Hot Compost Starter

Hi Betty and thanks for your question, it's one many beginning composters have in one form or another. There are four possible problems here…
• too frequent compost turning or stirring
• the mix of compost ingredients
• your expectations about temperature
• moisture level

Compost Turning

You say your husband is stirring the compost everyday. Much of the stuff you read about composting tells you to turn the compost pile to get it to heat up. And at times turning the compost will do just that… if the problem is that the oxygen in the pile has been used up. But turning the compost also cools things down.

The heat in the compost comes from the respiration and other metabolic processes the bacteria in your heap are going through. Leave your compost to sit longer between turnings. This may be all you need to do… give it time to get up to the hotter temperature range. By the way, if it climbs up to 155˚F you need to turn it pronto in order to cool things down.

The Mix

You are doing a three to one ratio, three parts browns to one part green. The mix you are using is going to give you a cooler heap. Generally speaking you will get a hotter compost when you have lots of compost greens. It will run a lot cooler with high levels of browns.

Use a one to one ratio for a hot compost. Your compost starter is likely a high nitrogen green but with the amount of paper in the pile it's just not enough.

You are trying to do a hot composting process but you are continuing to add and mix in new material. Hot composting is a batch process. You start with everything you're going to compost, preferably a cubic yard (roughly a cubic meter) of material. If you add in new material you have to more or less start over and I suspect this is part of why you are having difficulty.

Temperature and Pathogens

We all seem to think we have to get things super hot to deal with pathogens. While it is true that those pathogens are quickly rendered harmless at the magic 131˚F or 55˚C, they can also be dealt a death blow at lower temperatures. Pathogens are rendered harmless by a combination of competition with other microbes, temperature and time.

The good news is the competition is fierce at lower temperatures because more of the microbe enemies of the pathogens will be active in the mix. This means you don't absolutely have to get your compost up to the 131˚C temperature.

I like to use Joseph Jenkins' information on temperature and pathogens. He is the author of Humanure, a book loaded with information about composting human poop. Why I like it is that it deals with the scariest of the pathogens, and it was first written as a master's thesis so is very well referenced. According to Jenkins human pathogens are destroyed at:
62˚C or 144˚F in one hour
50˚C or 122˚F in one day
46˚C or 115˚F in one week
43˚C or 110˚F in one month

You can see that at high temperatures pathogens die fast. Bear in mind that they aren't the only deaths. Your beneficial bacteria are also keeling over. The true magic of compost is the biology. If things get too hot you lose the biodiversity and that is a bad thing.

Water

The final reason you might be having issues with your compost is moisture. Here is Southern Alberta we have dry conditions and about 90% of the problems people have with compost is because the compost has dried out too much.

You are the best moisture meter available. Just reach in and take a handful of compost from the heap. Squeeze it.
• If just a drop or two of water comes out all is well water wise.
• If no water comes out you need to turn the compost while adding water.
• If a steady stream of water comes out it is too wet and you need turn the compost while adding something dry like paper.

Good Luck People
Leslie