There are several possible causes for a compost pile being too dry. Choose the most likely cause and address that.
If the pile remains dry or quickly becomes dry again, choose the next most likely cause and follow instructions for addressing that. Keep trying the solution for the next most likely cause until you solve the problem.
Not Enough Water Added When Building the Pile
Solution: Res-tack pile, adding water every 4-6” until materials are about as wet as a wrung-out sponge.
This is a common problem with new composters, or those who are new to building hot batch piles. A lot of water should be added after every 4 – 6” of materials are added to the pile. Less water can be added if you are using fresh manure, water-logged coffee grounds or other moisture-rich material. But for yard waste, you definitely have to add water.
You have to add water after every 4 – 6” layer when you build a pile. It is not enough to build the pile and add water later. The reason for this is that leaves and other yard wastes were meant to shed water. When you water the top of your pile, it does not “soak in,” it runs off. Therefore it doesn’t make it very far into the pile.
Not Enough Nitrogen Added When Building the Pile
Solution: Re-stack pile, adding more nitrogen materials as you go, water every 4-6” until materials are about as wet as a wrung-out sponge.
Nitrogen materials in general release moisture as they decompose. They also enable the pile to decompose faster so that it doesn’t have as much time to dry out.
Solution: If you can, move the bin to a less windy location. Re-stack pile, adding water every 4-6” until materials are about as wet as a wrung-out sponge. If you have more nitrogen materials, you can add them too. If you were not able to relocate the bin, put up a wind block.
An excessive amount of air moving through a pile will dry the materials. The pile must be rebuilt to return it to the appropriate moisture level, then some method must be employed to block the wind. If you can move the pile behind a bush or fence, for example, that is a good idea.(Make sure the pile is located at least 2 feet from the fence if the fence is wooden.) If it is not convenient to relocate the pile, you can make a wind block. A good wind block can be made by stacking bales of hay or bags of leaves on the side(s) from which the strongest wind blows.
Hot, Dry Conditions
Solution: Re-stack pile, adding water every 4-6” until materials are about as wet as a wrung-out sponge. If you have more nitrogen materials, you can add them too. Then cover the pile.
If conditions are not particularly windy but just very dry, moisture may be evaporating out of your pile. The best way to maintain the moisture level is to cover the pile. Some bins come with covers. Covers can be purchased separately.
I usually throw an old shower curtain or other sheet of plastic over the top of the bin and weigh it down with bricks or stones. There has been some concern over the disintegration of plastic products, though, so it would be more organically-correct to use a sheet of aluminum instead.
As moisture from the pile evaporates, it condenses on the cover and falls back into the pile. One thing to be aware of when using a cover is that the “sweet spot” center of the pile may extend all the way to the top of the pile since the cover is retaining heat and moisture. This is great for your compost, but it means that when you take the cover off, there will be lots of decomposers right there on the top of the pile. Remove the cover with care.
This warning is especially included for people who are squeamish about bugs or in areas where some species of decomposers can be dangerous (fire ants for instance).
Mary Tynes, Master Composter, www.mastercomposter.com
Image credit (top left): http://www.flickr.com/photos/jessicamullen/4343691847/
Image (bottom right): Compost Converter (GREEN)