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Successful Manure & Waste Management
Cold Weather Adaptation
January 10th, 2008 by peter
Brent Danielson of Story City, Iowa, has altered the construction of our Micro-Bin system to accommodate an extreme cold climate. Here are his comments:
I built three insulated bins that have an R factor of about 20 or so. This has been allowing us to keep our manure composting when the temperature hits single digits and we had heavy winds for a couple of weeks. Because our bins are heavy and permanent, I set them up a bit differently. You can see how I plumbed them in the attached pictures.
The bin on the left is full and running over 100 degrees (it is on the downside of the composting temperature curve). I have loose hay on top for some insulation and then some wire screening and boards to hold a tar paper cover off the manure and allow it to vent air when the fan is on. The right bin is full of hard frozen manure waiting to melt. And the middle bin is about 1/3 full of frozen manure.
We do have a few problems. One of the biggest is that we have been collecting manure that is frozen very hard. Getting this to start composting may not be possible until spring, but it sure would be nice to get it started earlier. So we have had an unusual warm spell for the last 2 days and I have been blasting warm, wet air into the frozen bins. I think this is working as it is beginning to settle. In a couple more days, I may have it running. But I need a better insulating blanket on top. I have used hay and leaves for top insulation and both get wet from condensation and compact – which seals off the air flow. I think something like a quilt made from loose weave plastic burlap or even some sort of netting and filled with crushed Styrofoam packing peanuts might keep in the heat fairly well while allowing air and moisture out. What ever it is, it has to breathe, be impervious to water, and not freeze stiff when wet and cold. I haven’t found the ideal material yet, but I will eventually. If I was really smart, I would also figure out how to run the excess heat from one bin into a frozen bin to get it started. I can imagine how to do this, although it would be a bit of a plumbing nightmare. In any event, this is our operation, and it works quite well. Thanks for getting us started on this.
Comment from Peter: Last winter I had a similar problem in NH with frozen manure being delivered to the compost system and then not thawing out during periods of extreme cold weather (logically). We recommended that our client use heat cables from the greenhouse industry to get the core temperature up to ~70 degrees F to kick start the biology. These are much like block heaters for your car. They are inexpensive and I think will work quite well in your application. As for a cover, I suggest using 2-3 foam board cut to fit with small gaps between individual panels. You can lay on top of these and then bungee cord them into place. These would be inexpensive, easy to handle, and quite effective – at least in concept.
5 Responses to “Cold Weather Adaptation”
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Email received from Brent Danielson on 2/29/08:
Peter, I have been meaning to email you for a week or two about the results of adding the soil-heating wires. Our weather has been very cold with overnight temps falling to single digits almost every night and often much further than that. Yet, after a lengthy time to thaw the manure, I saw one of the more beautiful sights one could ask for – heavy steam billowing from the manure bins in the moonlight. Temperatures of -15F and yet we have a bin temperature of 150F.
So all is well and perking away, even though spring remains unsprung and there is no sign that it might ever arrive.
Brent
150 Degrees is actually quite high (From what I experience). Is your compost Fungal Based or Bacterial based (I find that that alters temperatures, what do you think?)
Also, how is your bin insulated? If your temperatures are remaining above 111 degrees I don’t think it is worth heating the pile.
Although I don’t like advertising products on a blog, I find that insulating bins with a product called Tiger-Foam (www.tigerfoam.com) works quite well.
The heat in a composting system is the result of bacterial activity in the first 30 to 45 days of composting (referred to as “Active Composting”). The maximum heat and duration of heat production is a function of the feedstocks being composted. Horse manure has moderate “heat potential” and more nitrogenous materials (e.g. lawn clippings, chicken manure, etc.) have high heat potential.
In a high energy pile, it is not unusual to see pile temperatures as high as 160 degrees F. This is a good thing for destroying parasites, pathogens and weed seeds in the mix but, in fact, lower temperatures in the range of 110 to 120 degrees F is a desired range for efficient composting.
To cool the pile down, we increase the airflow into the pile to drive off excess heat. The challenge is that we also drive off moisture, which can compromise the process if the moisture content drops much below 50%.
The secondary stage of composting (referred to as “Curing” or “Maturation”) is predominantly a cooler fungal driven process. During curing, the fungi are working on the more resilient forms of carbon – typically cellulose (hay) and lignin (wood).
For cold climates, we recommend constructing bin walls with insulation in the core. This can be done in several ways but a simple technique is to sandwich a layer of foam board between two sheets of 1/2 inch plywood.
The idea to add a 4′ electric heater cable prior to filling the bin in late Fall/Winter is just BRILLIANT!! I lost almost six months of composting time here in New Hampshire last winter because my bin froze solid in November. It wasn’t until this March that my “Jello Pudding Pop” finally thawed out. The heater cable will be added next Fall.
It is amazing how much heat is given off! I just started a new batch yesterday and in less than 24 hrs it’s 116F in there. Typically, it climbs about 12-15 degrees/day until 160F is reached.
I don’t have a front-end loader and fill my bins with the wheel-barrow and ramp method. After some trial and error testing, I found that adding a few gallons of water with the garden hose after each bin deposit is critical to starting the process.