What's That Smell?

It's been 17 days since I've been working on my compost. I add kitchen waste daily (in the very least, the previous days coffee filter with coffee grounds), and turn and water about every other day. After 17 days I can now turn the pile less often as it is starting to turn into a real, active compost heap. How can I tell? It is radiating a small amount of heat from the middle of the pile and is starting to get a smell.

What does the smell mean?

While it is normal for a compost heap to have some smell, it should not be a terribly awful smell. It should be a somewhat earthy smell, not a rotten one. One of the things many people warned me of when I first started up my compost bin was "it's going to smell". In actuality, a healthy compost should not have an awful odor!

If your compost smells rotten it means it is not getting enough air. Giving the pile a good turn will help circulate the air into the pile, and you should find that funky smell dissipate.

If your compost is too dry, it will often have very little to no odor, and may just smell like old grass. Moisten it while turning the pile to ensure it is being wet evenly throughout.

If your compost is too wet you will find it going moldy instead of decomposing like it should. Too much moisture is bad for your compost! Remember; it should have the consistency of a rung out sponge, not a sopping wet one! Turning the pile WITHOUT wetting will help dry it out. Having a lid on the bin can help keep extra moisture out, if you find you are getting more rain than your compost needs. The lid on my bin has plenty of slats with openings to let air in but keep some unwanted moisture out.

If your compost is damp, warm in the middle, but not warm anywhere else, the pile is too small. Try adding more browns to the mix to bulk it up. Mix the old ingredients with the new ingredients well so that the pile is evenly composting.

If the heap is sweet-smelling and damp but will not heat up, it means it is lacking nitrogen. Some nitrogen rich ingredients are fresh manure, bloodmeal or ammonium sulfate.