Soil Health Secrets: How to Build Resilient Garden Soil

Episode Description

Healthy soil is the foundation of every thriving garden. In this episode of The Evergreen Thumb, Erin explores the key principles of soil health and how gardeners can apply them to create resilient, productive soil at home.

Learn how to protect and feed the life beneath your feet, improve soil structure, and build a healthy, thriving garden using practical, research-based strategies. These principles make it easy to take small steps that have a big impact.

What you’ll discover in this episode:

The core principles of soil health and why they matter for your garden
How to keep soil covered, reduce disturbance, and maintain living roots
Ways to encourage diverse soil life for stronger, healthier soil
Simple actions to build resilient soil in your backyard, vegetable beds, or flower gardens

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Resources

Transcript

[00:00:00] To The Evergreen Thumb, episode 57.

I’m your host, Erin Hoover, and today I thought I would take a deeper dive into the principles of soil health. In our last episode with Tessa Halloran, we kind of briefly touched on some of those concepts, but I wanted to take it from the perspective of a fantastic book I read several years ago, called Dirt to Soil by Gabe Brown.

About Dirt to Soil

Uh, the first half of the book is his journey from a traditional farmer-rancher in North Dakota to adopting a more regenerative agriculture philosophy on his ranch and what that did for the health of his ranch, the health of his animals, and the profitability of his farm as well.

Now, I know most of you are not ranchers or large-scale farmers, but in the second half of the book, he focuses very heavily on the principles of soil health and how to make changes to our own farming and gardening practices to maximize our soil health in our gardens and farms.

This book was released in 2018, so it’s not new, but a lot of the things that he talks about in this book are still very relevant, if not more so, and the regenerative agriculture movement is actually continuing to gain traction because we have a better and better understanding of soil health and the effect that how we interact with our soils has on their health.

So the USDA has a lot of information on their website about soil health, and even in the time that I’ve been gardening, I have seen a lot of the information that they provide become progressively better and better, as we have a better understanding of the science behind soil.

The difference between the USDA’s principles of soil health and Gabe Brown’s is that he has five principles, whereas the USDA has four.

What Differs between Gabe Brown and the USDA’s Principles of Soil Health

[00:02:00] He still uses those same four, but he adds a fifth one that the USDA kind of incorporates into the other four as part of them as opposed to calling it out as a fifth one. The general principles are the same, whether you’re looking at this particular book that I’m talking about.

First Principle: Limiting Soil Disturbance

So, the first principle that I’m going to talk about is limiting or minimizing disturbance — and we’ve talked about this before — is no-till gardening, limiting or minimizing disturbance that goes beyond just not tilling.

And really for in some cases, never tilling is not practical. Personally, when we were establishing our garden space, it was a very compacted soil, and there was a lot of grasses. So, we made the decision to till that up one time to break it up, pull off the worst of the grass, and continue to build soil from there.

Physical Disturbance

[00:03:00] Other ways the soil can be disturbed include livestock, it can be chickens, goats, or even your pets running around can have an impact on the soil. Some disturbance is just unavoidable, but minimizing it as much as possible, it helps to build healthier soils. That’s just the mechanical disturbance.

There is also chemical disturbance and physical disturbance, and again, that’s where the livestock comes in would, be the physical disturbance. Chemical disturbance, if you are routinely adding fertilizers or pesticides, herbicides, um, things like that to your soil, um, that is a form of disturbance. And when you’re amending the soil, even with natural things like, uh, compost or manure or even if you’re amending with things like sand or uh, lime or whatever that is that your soil needs, you have to be careful when you’re disturbing that.

[00:04:00] When we put compost in our garden bins, I leave it as a top layer. I don’t turn it in. Um, I let nature do that work for me. The microbes, the worms in the soil, the watering. Watering is gonna wash those nutrients down. The microbes on the soil are gonna consume that compost, and it’s gonna work its way down that way as it goes through the food chain.

So there are a lot of ways to get those inputs into the soil without turning them in or tilling them in. I know Tessa talked about soil aggregates and how tilling breaks those down, which decreases water infiltration, accelerates the breakdown of organic matter and infuses oxygen into the soil, which can also feed opportunistic bacteria so that the soil bacteria can become out of balance.

[00:05:00] Bacteria in the right balance create those, the natural glues that hold those aggregates together. Basically, what all of that boils down to is that repeated tilling leads to anaerobic conditions in the soil.
Another aspect of tilling that I don’t think we’ve talked about in depth is that tilling breaks up the mycorrhizae, which are those the fungal networks that you see, you know, if you’re digging in, in your soil and you see these like white strands, um, that’s the, the hyphae. And by tilling, you’re actually breaking those up. All those strands altogether is one organism, and they actually create a network that the plants can actually use to communicate between the plants.

[00:06:00] And I know that sounds a little out there, but there have actually been studies that suggest that these fungal networks will actually, if say a tree is being attacked by a pest on one side of a forest and there’s a strong network, they can actually send a chemical signal to all the other trees in that forest that says, “Hey, I’m being attacked, do what you gotta do to make yourself more resilient.” And so then the trees can. On a limited level, depending on what the, the pest is, they can chemically respond to make themselves less vulnerable to those pests.

Chemical Disturbance

So a little more about chemical disturbance. So the application of fertilizers and herbicides can destroy soil structure and ecosystem function.

[00:07:00] Herbicides and, and pesticides are not very discriminatory. And so when you are using a pesticide in your garden, more often than not, you are also killing the, the soil bacteria, the microbes, and the, the smaller insects that are in the soil. Glyphosate is a registered biocide, which means it does actually kill the biology.

So, from knowing that we can deduce that it is harming the soil food web, and applying any herbicide, fungicide, or pesticide will have an impact on some aspect of the environment.

Second Principle: Cover Soil Whenever Possible

The second principle is what Gabe Brown calls armor or the USDA calls soil cover. As a general rule, your soil should be covered whenever possible, and there are a lot of ways to do that.

There’s a, uh, a homesteader that I follow online and he likes to say, “Mother Nature is modest, she wants to be covered”, and that image kind of helps to make you think about how you can keep your soil covered, whether that’s using cover crops, using mulches, using a chop and drop method. Uh, in the fall when the plants are starting to die back, you chop ‘em off at ground level and leave the plant residue.

[00:08:00] We’ve done that with our corn the last two years. In the fall, we chop our corn off at the ground level and just lay it on the bed and it acts as a mulch and it breaks down and it provides habitat for, uh, insects. That’s worked really well for us. And then, depending on what’s left in the spring, we will take those corn stalks if there’s much left of it, and we will actually run ‘em through our little electric chipper just to kind of turn it into more of a mulch that’s gonna break down easier.

Think of in nature, whether it’s a forest or a prairie or whatever, bare soil is an anomaly. Our modern landscape aesthetic for a lot of people is this separated plants that are highly manicured, and there’s lots of bare soil in between them. That is a lot of work to maintain. Bare soil is very labor-intensive to try to manage and think of it as a, like I said, Gabe Brown calls it armor. Think of it like a natural coat of armor.

[00:09:00] That soil cover, whether it’s cover crops or mulch or plant residue, adds organic matter to the soil. Uh, it acts as a weed suppressant. Like I said, with our corn, we have little to no weeds all winter long, and so when I pull those off in the spring, I only have one or two little weeds in each bed that need to be pulled up.

And then planting cover crops when you terminate those and you don’t have to till them to terminate cover crops, that’s adding even more nutrients into the soil because of all that organic matter is being taken into the soil.

Something to keep in mind when a raindrop hits plant cover like a cover crop or plant residuals, instead of the bare soil, much of that energy is dissipated.

[00:10:00] So say it hits a leaf and so that water spreads across the leaf before it drops down, maybe to the next row, leaves or down, uh, into an understory plant, and then it hits the soil. When a raindrop hits the soil directly, it splashes up and it, or you can start to see erosion if it’s, you know, a large water event, you’ll see the water will just wash that away.

Wind erosion is almost as prevalent today as it was during the Dust Bowl, and you hear stories in the news lately about these giant dust storms there was in Arizona and Oklahoma, and that dust is now dirt instead of soil. So as soil health improves, especially through armor, earthworms and other cell biology will cycle through those surface residues more rapidly.

Again, that’s the plant residues I talked about. The healthier the soil, the more the soil biology is going to be able to work through those plant residues and break them down on their own without needing any help. It’s all about creating this cycle. Everything seems to come back to just improving that cycle.

Cover Crops

[00:11:00] So a little bit more about cover crops. When you grow a high-carbon cover crop, that means something that’s gonna have like a lot of green matter above the surface. You allow it to mature to the point where the flowers are just starting to be pollinated, and then if you have livestock, you can allow them to graze it if you don’t, or if it’s in like smaller patches in a vegetable garden where you wouldn’t necessarily want grazing animals in there anyway. You can terminate the cover crop with a wheat eater or a roller.

They have rollers that you can like rent or buy that lay the crop down. I see this more in commercial agriculture, but they’ll go through and they’ll roll down the crop so that it lays flat and then you plant your spring plants in between it.

[00:12:00] And that kind of mimics like livestock coming through. ‘cause they’re gonna walk on it and smash it down, but they’re also gonna eat some of it. Um, if you terminate by cutting it off by weed eating or a weed whacker or whatever. Everybody calls it a little bit something different. But if you do that, uh, you need to do that about six weeks before you’re going to plant into that garden bed.

That gives the, the green material time to kind of start to dry up and break down, and you can leave that on the surface as a mulch. Soil test will help guide what types of cover crops you may choose to, to grow, but also you can talk to your conservation district about what maybe your goals are, what you want cover crops to do for you, and they might be able to help with some guidance on mixtures or specific elements to add to your cover crops to help you reach your goals.

[00:13:00] And here’s a, an example that Gabe Brown used in his book. It says that in 2006, Burleigh County North Dakota Soil Conservation District did a demonstration on cover crops. And in that trial, a six-species blend of cover crop yielded two to three times as much biomass as a single-species cover crop.

So the diversity in that cover crop is also adding to the health and the biomass of each, the plants, they’re living kind of symbiotically so that they’re benefiting from each other to create more aerial plant parts, uh, which in turn gives you material to have on your soil. But the idea is that you want to return that biomass back to the soil, without tilling it in.

Cover Crops and Soil Hydration

[00:14:00] Some of the other benefits of that armor that the mulch, like we’ve talked about before, it helps suppress weeds. It helps prevent evaporation of water. But one thing I don’t think we’ve really mentioned is that those mulches and soil covers can actually impact the soil temperature, which in turn impacts plant health.

As our summers seem to be getting increasingly hotter. That’s really something to keep in mind. So when soil temperature is 70 degrees, 100% of the soil moisture is available for plant growth. At 100 degrees, only 15% is available for growth, and the remaining 85% is lost to evaporation and transpiration. At 130 degrees Fahrenheit, 100% of the moisture is lost to evaporation and transpiration, and at 140 degrees, the soil bacteria die.

[00:15:00] So I have a hard time imagining where our soils would get to 130 out to 140 degrees, but we had several. Days in a row over 100 degrees this summer. So based on that idea, the surface soil could easily be a hundred degrees. If it’s not covered, the plants are affected by those temperatures, and at 90 to 100 degrees, they just kind of shut down because they can’t take up the water, and if you’re watering when it’s that hot, you’re going to lose most of it to evaporation.

Third Principle: Diversity

[00:16:00] The third principle of soil health deals with diversity, and when we’re talking of diversity, we’re talking plants, animals, insects, and pollinators.

Increasing the diversity across your garden can help stimulate plant growth. It can break disease cycles. It can provide habitat for pollinators and other living organisms in your soil.

And one of the questions that Gabe Brown asks is, where in nature does one find a monoculture? You see acres and acres of wheat or corn or potatoes or even fruit trees, apples, cherries. Nature doesn’t operate in a vacuum, and having that diversity can make all the difference in your soil health.

You know, when you’re planting cover crops, plant a mix of crops, so maybe you have a vetch and a rye. You know, you can mix different cover crops together based on what your goals are, rotating your crops when you’re putting in crops like vegetable crops, think about what type of crop it is and what primary nutrients it uses.

[00:17:00] A vegetable that we consume the root of is going to use more of certain nutrients than say, something like a brassica, where we’re actually eating the leaves and the flowers.

Corn is a grass. It’s a very heavy nitrogen feeder. It is going to use a lot of the nitrogen in the soil. So by rotating the crop and putting a nitrogen-fixing crop in behind it, like beans, will help balance that.

Another option too is to integrate livestock. And when I’m saying livestock, I’m not talking necessarily cattle. Even in a small garden, you can integrate a couple of chickens or if you’re on in a city, maybe you can’t have livestock.

[00:18:00] Find other ways to mimic the actions of livestock. So chickens, they scratch and they naturally turn some of that soil without compacting it. They manure the soil and so they’re adding nitrogen and adding, uh, minerals. So if you can mimic that, then that can be highly beneficial as well.

Native Prairies as an Example of Plant Diversity

And one of the examples that Gabe Brown uses is, um, a native prairie. So when you think of a prairie or really get a good look at a prairie, you have different types of grasses, legumes, shrubs that all live and thrive together.

Some have shallow roots, some have deep roots, some have tap roots. Some are high in carbon, some are low in carbon, some are legumes. Uh, like I said. So they actually fix nitrogen. Um, and each of them play a role in maintaining soil health, and so that diversity enhances and maintains that ecosystem.

[00:19:00] So increasing biodiversity, we’ve talked about that a lot as it relates to plants planting a variety of types and shapes and sizes and plants and flower shapes and things like that.

But also think of natural spaces. Forests, you’re going to see a natural diversity. You see two or three tree species that tend to grow together, and they tend to have the same groups of understory plants that grow underneath them.

Fourth Principle: Maximizing the Presence of Living Root

So, the fourth principle is maximizing the presence of living roots, maintaining roots in the soil as long as possible throughout the year.

Which is another reason why I chop ‘em off at the bottom to use as a, a soil cover. But some of the other ones, I just leave them in place and then let them live as long as they can, um, until they’re winter killed.

[00:20:00] Living roots feed soil biology by providing carbon, which is the basic food source and then the biology in turn fuels the nutrient cycle that feeds the plants.

So it’s, it’s a constant cycle. Some other ways to maximize the presence of living roots, again, cover crops. That’s a big one. You can use overwintering cover crops to keep living roots in the soil over the winter. Those plants will slow down their growth in the winter. A lot of ‘em won’t die off, especially things like vetch.

And again, use the diverse crop rotations so that way you’re getting a variety of different kinds of roots in that soil. So you can do like Daikon radish is a really long, deep tap root that helps break up compacted soils and then leaving those roots in the soil when you cut the plant residue at the top, those roots will provide channels for water to permeate the soil and then for nutrients to percolate down into the soil.

[00:21:00] So those, those channels also have a benefit. So, maintaining living roots in the soil as long as possible throughout the year is going to give you the best result. As Gabe Brown says, “never ever pass up the opportunity to convert solar energy into biological energy”. As soon as you’re done harvesting one crop seed, another crop, whether it’s a cover crop or a succession, or you know, a new season.

And that’s where also again, the crop rotation. You don’t just have to rotate your crops by year. You can grow crops year-round if you’re rotating ‘em right.

Sometimes you’ll do cover crops in the spring, sometimes you do cover crops in the fall to overwinter, and that again goes back also to the armor.

[00:22:00] So by keeping a crop in the ground all the time and rotating through, you’re providing, you’re feeding your soil year-round and it keeps this, this nutrient cycle working. Having living roots in the soil also helps to enhance and proliferate the mycorrhizal fungi because they feed on the exudates of those roots and it allows them to proliferate and expand, which just keeps that cycle going.

Fifth Principle: Integrating Animals

The fifth one that Gabe Brown uses is integrated animals, and we talked a little bit about finding ways to use small livestock, if that’s possible for you.

Integrating livestock has a number of benefits, and this applies more to grazers and browsers, but actually browsing on those plants stimulates the plants to pump more, more carbon into the soil, which drives the nutrient cycle by feeding the biology.

[00:23:00] So even if you don’t have animals that you can put, say in your vegetable garden, go in and try to mimic that process. Take just take a little bit here and there. It’s kind of like the cut-and-come-again lettuce, so that you can, you can cut some of that lettuce off and the plant will continue to thrive, but you’re also, at the same time, you’re helping the soil.

Think beyond livestock when it comes to integrating animals. Provide habitat for small animals, birds and lizards and salamanders. Pollinators, create pollinator habitat in your gardens, predatory insects, earthworms. These are all animals too. When they say integrate animals, these animals apply. We’ve talked a lot in the past about creating pollinator habitat, and those things are also a function of healthy soil.

When you think about it, hundreds of years ago, before European settlement, there were tens of millions of bison, elk, deer, and other ruminants that roamed all over North America. They took a bite out of a plant here and a bite there, and so then those plants released root exudates to attract a biology that supplied the nutrients they needed for regrowth.

[00:24:00] And predators kept the herds of ruminants on the move so they didn’t return to that same spot for long periods of time. So the plants had ample time to recover, all while putting huge amounts of carbon into the soil. Once you add insects, birds, and all the other wildlife that live in these environments, it was an optimally functioning ecosystem.

So, so try to keep that in mind and say, okay, how does this work in nature, and how can I mimic nature, or how can I let nature do the work for me? You may not be able to put livestock of on your gardens, but you can find ways to mimic the actions that livestock take.

Final Thoughts

Well, that wraps up another episode of The Evergreen Thumb.

[00:25:00] I hope you found that useful and that maybe you take a deeper look at what soil health can do. Please feel free to email me your questions about soil health or anything else we’ve covered in the podcast for that matter. And if I don’t have the answers, I can probably find a WSU scientist who does.

Thanks for joining me today, and we’ll be back in two weeks.

Thank you for joining us on this episode of The Evergreen Thumb, brought to you by the WSU Extension Master Gardener Program volunteers and sponsored by the Master Gardener Foundation of Washington State.

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