Has it actually ever occurred to you that worm compost could even have salt issues? It came as a surprise to me! Somehow I didn’t equate my food scraps with toxic salt levels.
But that’s me. I’m not much of a worrier. I sometimes kinda jump in and figure things out as I go along.
Luckily, worm composting is a perfect platform for just that kind of free-spirited recklessness! But could that be dangerous? Might a happy worm farmer like me (or you?) be caught unaware… of too much salt in their worm bin?
Not today, cowboy.
How does salt in worm compost affect worms?
First of all, let’s learn about salt.
According to Dictionary.com, “Salt is a crystalline compound, sodium chloride, NaCl, occurring as a mineral, a constituent of seawater, etc.” Sure, that’s interesting, but there is one very important thing that it doesn’t mention.
Salt is hygroscopic, which means it absorbs or attracts moisture from the air… or anything else it touches.
Salt in the worm bin draws moisture out the air, bedding, and skin the worms live within. At nearly 90% water themselves, a worm requires very humid living quarters to stay well-hydrated.
And what’s so important about being well-hydrated?
It’s a matter of life and death. A red wiggler breathes through a slippery mucous membrane instead of the lungs. Drying out means they suffocate and you lose your worm work-force.
Does salt affect the quality of my worm compost?
Worm compost is a highly valued resource in the gardening world. It’s shown to heal soils, bring about lush verdant growth, and restore balance to barren areas. It bumps up the productivity of fruiting and flowering plants and is even called Black Gold!
However, when salinity offsets the critical balance- worm compost is no longer as effective or valuable. University of California Agricultural and Natural Resources poses that high salinity both prevents plants from getting the water and nutrients they need, while also toxifying them.
Effect of Salt Toxicity in Plants
Over time, the soil of many potted, garden, and landscape plants can become over-salinated. Interestingly, the addition of BALANCED worm compost and worms to salty soils has been shown to help reduce and reverse salinity in some areas.
Are your plants telling you their soil is too salty? This is how you might know:
- Wilting during hot, dry conditions
- Reduced plant vigor
- Flower and fruit development delayed and/or smaller than normal
- Fewer and/or smaller leaves than normal
- Discolored foliage
- Nutrient deficiencies
Despite the potential effects, the University of Massachusetts Amherst Center for Agriculture, Food, and the Environment shares some hope, “The extent of damage can vary with plant type, type of salt, freshwater availability and volume, movement of runoff, and when salts are applied.” Which leads us right into our next point.
How does salt in worm compost rise to dangerous levels?
Believe it or not, this could happen to anyone. It’s happening in all of our bins, all the time. Really. The buildup of salt is unavoidable- to an extent.
Salt shows up in the sneakiest places. No wonder it so easily ends up in the worm bin. Here are the most common sources to be aware of:
Coconut coir is one of the most common bedding starter materials. It’s great because it has super absorption, and allows for drainage as well as superior airflow. Unfortunately, coconut coir also retains a great deal of salt absorbed from the air and seawater where it is grown.
Most natural food has at least a trace amount of sodium. Additions like those hardly make a difference. But just as often it’s our leftovers, our prepared foods, that end up in the worm bin. Were those foods cooked with seasonings? Add to that anything processed and already, the salt levels are soaring.
According to the Soil Guy, “Actively growing vegetable crops requires a continuous supply of balanced nutrients in the soil. Unfortunately, these are usually provided by the application of synthetic fertilizers which include soluble salts .”
As these accumulate, roots are damaged and eventually the tops as well. These commercial crops are the same ones that become our food scraps and thus, worm food in the worm bin.
Plentiful, effective, and relatively cheap, de-icing salt is a winter lifesaver. But 22 million tons a year make their way into our soils and waterways.
Many of us use grass clippings, yard waste, and soil to feed our worm bins. How much of that comes from along walkways or roads that were covered in salt just months ago? Where is that salt now?
Another significant source of salts is in our irrigation water. Yes, the same water we drink from the tap and use to irrigate our plants has measurable amounts of salt in it.
As the water in the worm bin evaporates, it leaves behind the heavier elements that make up salt, sodium (Na), and chlorine (Cl). Over time, these accumulate, raising the overall salt content of your worm bin.
Is it too late?
How to Prevent or Reverse Toxic Levels of Salt in Worm Compost
It’s never too late. To find some solutions we need only look at the sources of all that salt.
If opting for coconut coir, just rinse and repeat! That’s not so hard. But other bedding choices work just as well without the need to rinse and repeat. Dry leaves, shredded cardboard, partially complete compost; a combination of things is best.
Only add what red wigglers can eat to the bin. Be sure to rinse all food cooked with salt before feeding it to your worms. Avoid adding foods that are processed or packaged as they are likely to be higher in sodium.
Avoid commercially produced foods as much as possible. Avoid using fertilizer on gardens and lawns that will be used as worm food.
Be aware of what has been used on your property. Try to steer clear of using materials off the edges of sidewalks, driveways, and roads.
This one is key but in a different way. Proper drainage out of your worm bin is the best way to desalinate your worm compost.
A nice worm compost pour-over will rinse away much of the salt that has gathered over time. This can be tricky if you’re using a storage tote.
If that is what you have, drilled holes along the bottom and sides will provide a way out for that excess water. Lift your bin onto bricks to let the water flow freely from the bottom.
If however, you are composting with a Worm Factory 360 or other tray-style composters, a clean water flush will be much easier. Simply lift the top lid and use a watering can or pitcher to direct the flow of clean water over every bit of the top level.
How much you use depends on how full of worm compost your tower is. You want to use enough so that what goes in will be able to filter all the way down and out. Be prepared; the catch basin at the bottom will fill up with leachate!
Here’s an opportunity you don’t want to miss.
Collect that leachate to make a fresh batch of worm compost tea.
Now this one is my favorite because it’s a sure way to actually rid the bin of any material that may harm the worms. Every few months you should be able to harvest a load of finished compost. Whatever you remove can go right out into the garden or grass, along with the salts that will soon be washed away by the rain.
Worms who rely on a moist environment have a low tolerance for super-salty conditions. Keep your workforce happy with a low-sodium diet and proper worm bin maintenance. A regular schedule of harvesting will ensure the buildup stays to a minimum.
If any of this sounds like a lot, don’t worry, The Squirm Firm is here to help. Let’s worm together! Sign up here and once a month we’ll send you a free newsletter filled with tips, tricks, and expert advice to keep your worm composting fresh!
Thanks for doing your part to reduce waste and heal our soil! We appreciate you.
Happy worm composting,