What happens when you pour water on to a solid surface like a stone countertop? What happens when you pour water over a sponge?
These two scenarios are very analogous to something that you see every day but may not notice: soil compaction.
The simplest definition of soil compaction is the reduction of pore space in your soil. Soil that has been heavily compacted will not be able to:
- absorb or hold water,
- cycle nutrients,
- have good seed germination rates,
- provide sufficient oxygen to grow plants or allow plant roots to penetrate,
- have a flourishing soil food web or high microbiological activity necessary to feed and protect plants from pathogens.
Compacted soil is dead soil (or at least soil that’s on life support) that will not grow healthy plants. The good news is that you can take steps to both prevent soil compaction as well as steps to regenerate heavily compacted soil.
5 Ways to Prevent Soil Compaction From Happening In Your Garden
1. Don’t stand or walk in your garden beds.
We see many new gardeners and garden visitors breaking this rule, so it bears repeating: do NOT stand or walk in your garden beds where you intend to grow plants. If you do this on a regular basis, you’ll compact the soil.
2. Install garden paths and/or stepping stones.
What do you do if you need to walk around in your garden or step into certain spots to harvest? Install walking paths or stepping stones. Stepping stones do mildly compact the soil, but they work like snowshoes, distributing your weight over a broader surface area. If you’ve ever turned over a large stone in your garden, you’ll also notice that they provide great habitat for worms, beetles, and other critters that serve to aerate your soil for you. They also provide a visual reminder to you and others that “this is where you should step.”
3. Make the width of your garden beds no wider than twice your arm length.
As a general rule, don’t make your beds wider than 4 feet if you have a walking path on either side of the bed (this allows you to easily reach the middle of the bed from either side). If there’s only a walking path on one side of the bed, only make it as long as your arm.
4. Use raised beds or fencing if/when necessary.
If you have children, large pets, or a high-trafficked yard where you also want to garden, it probably makes sense to install either fencing or raised beds or both. Here are our top recommendations for raised beds if you’re in need.
5. Feed your soil, don’t till it.
We haven’t tilled our soil in the eight years since we made our garden beds, and we started with heavily compacted red clay. Despite conventional wisdom, tilling your soil is unnecessary and it’s actually quite harmful to the trillions of living organisms that make soil healthy. Instead of tilling your soil, top-dress it with mulch (shredded leaves, wood chips, cover crops) and let nature/biology do all the work for you. Click here if you want to read more about the how’s and why’s of no-till organic gardening.
How to Fix Compacted Soil
Are you trying to figure out what to do with soil that’s heavily compacted? The good news is you can regenerate healthy soil very quickly and with surprisingly little work. We’ve read piles of research on this topic and put that knowledge to work on heavily compacted red clay soil in our own yard.
- Medium Way (1 month) – Macro and microorganisms in soil are what naturally build and maintain healthy, living soil. When soil is compacted, those organisms can’t penetrate, move around, or find plant roots to symbiotically interact with. How can you quickly regenerate the health of previously compacted soil in your garden? First, till the surface or break it up with a shovel. Next, spread 2-6″ of high quality worm castings or compost on the surface. Finally, cover the castings/compost with 3-6″ of mulch. Make sure the area gets 1″ or more of water per week. Your beds will be ready to plant within a month. Just pull back the mulch by hand wherever you intend to sow seeds or put in transplants. Of course, continuing to add worm castings, compost, and mulch 1-2 times per year will continue to improve the health and depth of your living garden soil, so don’t stop going!
- Fast Way (1 day) – Have highly compacted soil but want to be able to “fix it” and put in seedlings or sow seeds the same day? If you’re more of a hare than a tortoise, no worries. You’re going to do pretty much the same thing as in #2, but with a few modifications. First, till or break up the top of the compacted soil with a shovel. Add worm castings or compost, but apply them more deeply: 6″ thick or more. Put in your seeds or seedlings, and instead of top-dressing the beds with 3-6″ of mulch, put down a thinner mulch layer about 1-2″ thick. Straw or pine straw works great here since a light layer won’t block out germinating seeds. If you want to use a heavier mulch like wood chips, taper them off wherever you’ve planted seeds so you don’t block the germinating seeds from reaching the surface. The compost/worm castings will provide your new seedlings with the bio-available nutrition they need while the microbes and plant roots start to bring life back into the previously compacted soil.
Again, regardless of which approach you take, the aim is to let biology do the bulk of the work for you.
If you want to really geek out on understanding how soil works and how farmers are using similar methods to regenerate healthy soil on large acreage, we strongly encourage you to watch this presentation by one of our heroes, soil microbiologist Dr. Elaine Ingham.