Editor’s Note: Scott Haase is a member of the SFA Board of Directors. He wrote this article for the Lake Pepin Legacy Alliance. Contact Scott at firstname.lastname@example.org.
For years, I’ve been watching the Blue Earth River wildly fluctuating in terms of its flow. It can be nearly dried up and then a week or two later it’s rushing and flooding over its banks. Too often, the river becomes a torrent of muddy brown water, forcefully making its way from Northern Iowa all the way to Mankato where it joins with the Minnesota River. That water passing by my backyard carries soil, fertilizer, and other more nefarious manmade chemicals as it moves toward St. Paul before turning south and making its long journey to the Gulf of Mexico.
Along the way, especially in the deeply carved valleys where the Blue Earth approaches the Minnesota, there’s relentless scouring of the river banks when levels are high, picking up even more sediment. In other places, like Lake Pepin, some of these materials settle and are left behind.
The unpredictable, muddy, sediment-laden flow is a result of the way the land is being managed throughout its watershed – soil health is now so impaired that the situation is getting worse. Natural processes will always be working to move material down a watershed, driven by gravity, the sun, and life itself. But not like this.
So what’s going on? Should we blame increased rainfall and more frequent intense storms? Are farmers to blame? They’re mostly good people just trying to earn a living doing the best they can. Is it a food system that values cheap commodities without examining how they impact the rest of the system upstream and downstream, figuratively and literally? Don’t get me started on that one! Maybe it’s the drainage tile.
What I think, as a sixth generation, getting-to-be-experienced farmer and a lifelong student of the school of nature is this: start with the soil. From the perspective of the soil, we’ve been going about things all wrong. Only a couple crops dominate and they only actively grow for a short portion of the year. Most corn in Minnesota matures about 100 days after germination and roots don’t even actively grow towards the end of this period. Soil is left bare and exposed. The microbial life in the soil is fed a steady diet of strange, often harmful, chemical compounds and synthetically produced fertilizer and not much else other than the leftover materials of the crops themselves. Imagine what it would be like feeding your children nothing but sugar and pharmaceuticals, along with maybe an occasional multi-vitamin, and expecting everything to be fine.
To begin to solve our problems, the soil, and more importantly the microbes that make it alive and functional, need to be the foundation. Here’s why:
Water and its interactions with healthy soil
Healthy soil holds more water than degraded soil. For every one percent increase in the organic matter content of the top six inches of soil, there is an increase in water-holding capacity of around 20,000 gallons per acre. Organic matter is the portion of the soil that’s a mix of carbon-containing compounds, some being very complex, derived from living material. It’s also the material, or organisms rather, that are alive and too small to be easily separated out: bacteria, fungi, protozoa, nematodes, and others.
But there’s way more that’s happening here; not only does the soil hold more, it infiltrates more. In other words, when rain falls more of it goes into the soil and slowly percolates through its layers. Contrast this with running off, gathering velocity and picking up things that should best stay put. I’ve personally seen soil’s ability to infiltrate water increase in a dramatic and measurable way after just a couple seasons of making some relatively minor changes in management. It seemed quite magical.
The way water interacts with soil is a complex subject. But what seems to be a key function is that microbes make a gooey substance called glomalin, a sort of biological glue that surrounds tiny chunks of soil called aggregates. In this aggregate form, the soil is protected from disintegrating and washing away when impacted by wind or rain. The spaces between the aggregates hold air, water, and provide critical habitat for even greater levels and diversity of soil life. A principle of biology is that life creates the conditions necessary for more life to happen.
By infiltrating and holding more water, more of that water, potentially a lot more, stays put. The landscape as a whole becomes better at buffering between droughts and floods, more like the prairie and savanna ecosystems once did, thereby helping our sediment problems.
Healthy soil provides plants what they need
Over millennia, soil life has arisen for the mutual benefit of both plants and the soil microbes themselves.
Plants are amazing. Go to your favorite wild area and you’ll notice the diversity and abundance of plant life, especially here in the Midwest where water is relatively abundant. Plants in these wild areas are doing all right with what nature provides. Now, we could argue that some of the “fertility” that accumulates in almost every nook and cranny of the landscape as a result of current land use has an impact, but no one fertilized the prairies and we still ended up with thick, black topsoil. Previously mentioned was the lack of diversity that comes with planting mainly two warm-season crops on the vast majority of the landscape. Contrast this with a natural system where dozens if not hundreds of species grow in relative harmony from early spring to late fall.
Even when no one’s weeding or applying fertilizer, nature protects plants through compounds that repel pests and environmental stressors, promote growth, and eventually create seed. Soil microbes play a critical role here. Descriptions of the complex relationships between the fungi and bacteria that associate with plant roots can fill books, and soil scientists only understand a small portion of what’s going on. Soil scientist Dr. Kris Nichols remarked that when she started grad school, scientists thought they had identified 10 percent of soil microbe species and by the time she finished this number had been revised to 0.1 percent.
The biological system around plant roots is complex. Mycorrhizal fungi feed on root exudates, sugary substances that the fungi like to eat, from these roots. In turn, through their tube-like structures called hyphae, the fungi deliver whatever nutrients the plant lacks. These fungi are incredibly adaptive and masters at producing the right chemistry to extract and transform an array of materials. Entire books have been written about this fascinating subject and what it means for everything from cleaning up chemical spills to producing new medicines. And one important detail: different plants produce different exudates, feeding different fungi, which is an important reason why plant diversity is essential.
We know that plants and microbes all work together to get what they need. The plant eats, the fungi eats, and bacteria often play a role. When there’s enough diversity in the soil and plant life, this arrangement works very well and the fertilizer and pesticides normally used in agriculture can be significantly reduced (mycorrhizal networks in soil also act like an “internet” for plants to communicate with each other, even across species, but we’ll let that be a subject for another time).
Building healthy soil requires a systems approach
What happens if we put the first two concepts together? First, we have less water leaving an area where soil health has been prioritized. Here, the water that does flow out tends to be slow and steady, its kinetic energy absorbed through the soil profiles. There’s little, if any, runoff. Now, add the second concept: the quantities of fertilizers and pesticides can, and should, be reduced once soil microbes perform their designed functions. Farm inputs that kill life or are used as an attempt to directly supply plants with nutrients usually aren’t good for soil life. Consider this example: if the mycorrhizal fungi described above aren’t providing a needed function for the plant, the plant won’t feed and support them and the web of life begins to collapse and degrade.
By putting these concepts to use we have less water leaving with less “stuff” in it that’s detrimental downstream. Win-win! But wait, there’s one more thing: Healthy communities of soil microorganisms can actually break down toxic pesticides more effectively. Less used, more is rendered harmless, and less runs off. Win-win-win! Once we start to understand and put together the principles farmers and anyone working on the land can employ to build healthy soil it becomes apparent just how impactful it can be.
I am hopeful that, someday soon, the river that runs through my backyard will flow a little clearer, carrying less of Minnesota’s valuable topsoil to the Gulf.