Cold Composting Setup
April 28, 2020
Hi there! I am wondering what kind of structure I should build to protect my compost pile. I don't have plans to buy a plastic bin at the moment. Just was planning to throw cut up scraps on a pile that will be safe from my dogs. I could build some sort of barrier frame with wood, but does it need a top to keep the moisture in? Also, do I need to turn the pile periodically? Thanks!
Answer by RR: Other Master Composters may also reply, but here is my response. First of all, thanks for composting instead of just throwing away your scraps. You may have already our desert composting handout on our website (see Desert Composting under Composting Info in our website menu) but on the last page, the diagram shows why we should cover our compost piles with an impermeable cover (tarp, trash bags, or whatever). First, it will prevent the nutrients from leaching into the ground when it rains. But more importantly, since it doesn’t rain much here, there is still a significant amount of condensation generated from inside the pile itself. Without a cover, this will just evaporate; with a cover, you can hold that moisture in your pile and reduce the frequency of adding water to maintain a 50% moisture level. In addition, if you are going to build a structure, don’t build one like you see in most places that tell you how to compost. Our website is the only one I’ve ever seen that talks about composting in the desert. All others show you how to make a composting structure with a lot of air infiltration all around. This will just require you to regularly moisten your pile even if you do cover it. We recommend eliminating these air holes and using course bulking materials to hasten air flow in your pile.
Turning your pile is optional. Just realize it will take longer to decompose if you don’t turn it. The end result will be just as good; it’ll just require more time. One time you definitely want to turn it, however, is if it starts to smell. That likely means it has gotten too moist and has started to go anaerobic. So then add some carbonaceous material (browns) and turn it.
I recommend reading the handout material on our website about hot and cold composting in the desert. Hope this helps. Happy composting.
From original questioner: That’s great, thank you! So it sounds like I don’t really need a structure of any sort, rather just a pile covered with a tarp is optimal. I’ll read the handout after work today!
Answer by JH: Correct, tossing feedstock on the ground in a pile with the cover RR describes is perfectly suitable. And if you don't intend to harvest the finished product for use elsewhere in the yard, you could just bury the scraps which would prevent the need to ever turn, water or cover other than soil on top to keep your dogs and other critters away.
Have fun and after you get started, if you are interested in taking a class we'll have the schedule posted when it is possible to again hold classes.
Answer by RR: A structure just helps to keep the contents consolidated, add some aesthetics, and maybe discourage some critters. Also, if you are building a hot pile, it needs to be at least a cubic yard, and that is much easier to contain with a structure. But it sounds like you just want to be able to, as we call it, “dump and run,” which is a cold composting process, and there are no size requirements for that method. Good luck.