The Soil Habitat

Jul 29

How we create the ideal conditions for beneficial soil microbes

We like quick fixes. During my time as an upland bird biologist, I remember countless times a landowner wanted to release quail to increase numbers. There was just one problem—they didn’t have the habitat to support those birds. It’s not all that different from our soil. We can add all the microbes and compost we want, but if we’re not providing and managing the habitat for those microbes to thrive, it won’t matter. We won’t have healthier soil; we’ll just have another input.

So how do we create the ideal habitat for our beneficial microbes to thrive? First off, I think it’s important to remember that nothing happens in isolation. The soil is an ecosystem. If we want to create microbial habitat, we must recognize that microbes interact with each other and with plants. If you recall from the previous post, plants feed the soil microbes. If we want healthy microbes, then we need healthy plants. And what those microbes and plants need in their habitat isn’t all that different from what we need.

There’s 4 things you or a soil microbe need for survival:

1. Air

2. Water

3. Food

4. Shelter

Well, that’s straight forward. So what do those look like for our soil ecosystem?

1. Air—our soil needs to breathe!

Why? If our soil is suffocating (anerobic) we:

· Select for disease-causing microbes. Yikes! Yes, beneficial microbes require oxygen to function! If oxygen gets too low in our soil (anerobic), then the not-so-beneficial microbes outcompete the beneficial ones.

· Decrease plant growth. Plants require a proper balance of air space and water for root growth. Remember the plant and microbial interactions that we discussed last time? The plant feeds the microbes. If we want healthy microbes, we need healthy plants too.

· Lose nutrient cycling. Our beneficial microbes require adequate oxygen to cycle nutrients. Anerobic soil = low nutrient cycling

· Lose nutrients from our soil. Ouch--that’s a double whammy! We not only lose the ability to cycle nutrients, but we also lose the nutrients we have. Nutrients such as nitrogen, sulfur, phosphate, etc. are released from the soil as gases when we have anerobic soil.

· Don’t have pore spaces to hold water. We don’t capture as much rainfall, making us more vulnerable during drought. We increase run-off and erosion making us more vulnerable during floods.

How do we ensure we have air in our soil? Soil structure! We want our soil to be like a sponge, lots of pore space to hold air and water. Guess who builds soil structure? Our soil microbes! But to do so, they must be fed!

3. Food

I’ll beat this like a dead horse. Who feeds the soil microbes? Plants! To produce these exudates (sugars and other compounds), we want to maximize photosynthesis—that’s how the sugar is made. To do so, we need adequate water, and air space for the plant, but we also need to manage the solar panel—the leaf—that is capturing the sunlight. We do that through our grazing management (more on that later).

The food sources our soil microbes utilize include:

· Root exudates – sugars released into the soil by the plant.

· Organic Matter (OM) – we want our soil to be at least 3% OM. OM plays an important role not only as food, but it allows our soil to hold more water and it keeps our minerals from leaching out of the soil.

4. Shelter

Ever stepped into a corn field on a July day? There’s generally a lot of bare soil in a crop field, it can get pretty darn hot for our underground livestock too. We need to protect our microbes by keeping the soil covered.

A covered soil can:

· Shelter microbes from extreme temperatures

· Cycle nutrients. If our soil gets too hot, our microbes don’t function and nutrient cycling stops.

· Protect the soil from water loss due to evaporation.

· Protect soil from heavy rainfall which can cause compaction. A compacted soil is a suffocating soil because we don’t have the pore space to hold air and water.

With all that in mind, how do we create this ideal habitat? By mimicking nature. That’s what the Principles of Soil Health are all about:

1. Armor on the Soil

2. Living root in the soil for as long as possible

3. Minimize disturbance (tillage, overgrazing, & chemical)

4. Integrate livestock

5. Maximize diversity

6. Recognize the principles, but realize the practices need to fit your specific context

I want to emphasize that last one, because I think it’s probably the most important. And one I wish I had understood sooner during my time as a biologist. I think back to some of the success stories from my time as a biologist. Several of those didn’t involve the stocking of birds. They simply created and managed for the habitat they wanted, and the birds showed up on their own. I believe stocking birds or microbes has its place, but sometimes if we just manage the habitat, they’ll come. It starts with the habitat and sometimes it doesn’t hurt to speed up the process. When you’re ready to “stock” your soil with microbes, it’s important to make sure you’re stocking it with what you need—always test your compost! Drop us a line if you would like to know what you are feeding your soil or if you’d like to learn more about managing your soil habitat.