O2Compost Hot Topics

Severe Winter Questions/Concerns

April 3rd, 2008 by peter

Questions posed by Jolene Fenwick of Wisconsin on April 2 - and Peter’s responses:

Hi Peter… I’ve been doing some more reading on your system because I think it is a great concept for our stables. I have questions/concerns about our severe winters. Specifically, I’m wondering about: 77″ of snow thsi year and -40 degrees a couple days. It is very typical to have -0 nights and highs in the single digits for 2 months of winter. The ground is frozen fro 6 months out of the year.

Does frozen manure work in the system? Even our stall manure is frozen in the middle of winter. How do bays get “cleaned” in between batches? How long is the complete process from fresh to cured in 10 degree weather? Does the finished product freeze solid in the bay?

Peter’s Response to Jolene’s Email:

Jolene… This is an excellent set of questions. Up until a year ago, I wouldn’t be sure how to answer them however we’ve been working with a client in Morrisville Vermont who experienced these same conditions and we “redesigned” her system for extreme cold and this year all went quite well.

First, our systems use post and beam construction. For each bay, we place boards (e.g. tongue and groove 2 x 6’s) on each side of the posts to create double wall configuration. We then fill the hollow space with insulation. This can consist of foam board; spray-in, expandable foam; vermiculite pellets, etc. Finally, we place a 2 x 10 cap on top of the wall to seal in the material.

Second, we construct light weight, removable, insulated panels for the front to prevent excessive heat loss through the slide boards. These panels may be constructed using 2 x 2’s and thin plywood on each side (much like a hollow core door), again with insulation on the inside. We would use these panels only during the extreme cold periods.

Third, we place an insulated cover over the top of the bay when it is full. We have played with a vareity of designs, but a simple one consists of two layers of poly-tarp with flexible insulation sandwiched in between. We use grommets to create a single unit. This is light weight and easy to handle.

Finally, prior to filling the bay, we coil a 48-foot length of heat cable on the slatted floor (these are inexpensive and available on the internet through a variety of greenhouse suppliers). This acts just like a block heater for your car.

Operationally, you do your daily chores removing the manure and bedding from the barn and fililng the bay. Everything can be frozen solid - not a problem. When the bay is full, we plug in the heat cable and allow it to thaw out the core of the pile over a few days and once the core of the pile is up to 60 or 70 degrees (max for the heat cable), the biology will take over and bring the pile temperature up to the desired levels.

One key is to minimize aeration so that we don’t cool the pile excessively and, more importantly, so that we don’t dry out the material to the point where the biologic process crashes.

The second key is to not let the compost stay in the bay too long. Generally, the process is roughly 30 days long, but it is okay to cut it short so that we can remove the mostly-composted material from the bay before it returns to a frozen condition.

In designing the system, you may also consider over-sizing it somewhat so that you can receive the raw manure, compost it, and then allow it to cure / store in the same bay until the spring time. This obviously results in a larger system and will cost more, but it may also be worth the convenience of not having to move material when it is well below zero.

PM

Posted in Cold Weather Composting   

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