QUESTION: Can you put baking soda in compost? I have a big box of it that is expired and I’m also wondering if it might help with any smells like when you use it in the refrigerator. – Frances N
ANSWER: Especially if your compost heap has developed an unsavory aroma, you may be tempted to add baking soda to bring the smell back into the neutral zone, but don’t give in to that temptation. (By the way, any stench coming from your compost indicates a problem with moisture level or the balance of brown and green materials—unless you’ve been adding the forbidden materials of meat, fish, grease, or dairy products).
The reason baking soda works to neutralize odors is that it kills the microbes and fungi responsible for producing it. In composting, killing off microbes equates to certain death for your compost pile. After all, it’s those microbes that do all the work of breaking your ingredients down into nutrient-rich compost for your garden. So just ignore the tips you may have run across online that tout baking soda as an odor reducer for the compost bin.
If you were considering composting with baking soda due to odors, you should instead address the problem by correcting whatever is producing the stench. If your compost bin is putting off a smell similar to ammonia, the culprit is an overabundance of wet “green” materials heavy in nitrogen.
To address this problem, start by propping the lid of your compost container open on a sunny days so the sun can help you dry things out. If that doesn’t do the trick and things are still too moist, you can take the compost out of the bin and spread it out in a single layer to dry. You should also add in some drier “brown” ingredients that are rich in carbon, such as dried leaves, shredded newspaper, or cardboard.
If the smell you’re dealing with is a putrid one, like the smell of sulfur or rotten eggs, there could be a few possible explanations. If you’ve been including meat, fish, grease, or dairy products in the compost, there’s your culprit. You should not compost these materials because in addition to being stinky, they can bring in hungry wildlife.
If you haven’t been using these off-limits ingredients, then the smell is due to a shortage of oxygen in the compost, which causes a growth surge of anaerobic bacteria. First, turn the compost thoroughly with a shovel, pitchfork, or compost turner tool to aerate the pile and allow oxygen to circulate. You’ll also need to mix in some more “brown” ingredients full of carbon, such as leaves or shredded newspaper and cardboard.