By: Scott Haase, Blue Dirt Farm
I've been seeing it most of my life. The river, which I've made my home along, 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 it's 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 to Lake Pepin 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 River, 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. The health of the soil 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. Potential factors are numerous and this is not an exhaustive list!
What I think, as a sixth generation farmer, now beginning my 14th season, and a lifelong student of nature is this: while there's plenty of blame to go around, we really need to 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. For perspective 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.
Healthy soil holds more water.
Healthy soil holds more water than degraded soil. A statistic so commonly used in the soil health community that I've committed it to memory is that for
every 1% increase in the organic matter content of the top six inches of soil, there is an increase in water-holding capacity of 20,000 gallons per acre! The number actually varies but the 20k figure is a good low-end average.
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. The bacteria, fungi, protozoa, nematodes, and others. They're probably no longer alive once a testing process to measure their levels in the lab is complete. Sorry little fellas!
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 with fascinating things happening. But what seems to be a key function is that microbes make a gooey substance called glomalin. The glomalin (think of it as a biological glue) 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, less of that water, potentially a lot less, leaves rapidly and all at once.
The landscape as a whole becomes better at buffering between droughts and floods, more like the prairie and savanna ecosystems once did. Does that seem like it could help our sediment problems?
Healthy soil provides plant nutrients.
Soil life has been forming complex interconnections for millions of years in a system that 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, how much plant life there is, especially here in the midwest where water's relatively abundant. I think we can say that plants in these wild areas are doing all right with what nature provides them. Now we could make an argument 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. Remember how I commented above about the lack of diversity, mainly two warm-season crops, using the majority of the landscape (over 80% in my neighborhood!) Contrast this with a natural system where dozens if not hundreds of species grow in relative harmony from early spring to late fall.
But how exactly does nature provide plants with what they need when no one's weeding or applying fertilizer? The compounds plants use to protect themselves from pests and environmental stressors, grow, and eventually make copies of themselves somehow get into those plants!
While it's tempting to think of roots like little straws sipping up whatever they need from the soil, this isn't entirely accurate. Much of what's needed isn't in the right form, or it's mixed in with that dry clump of soil that's just out of the plant's reach! Keep growing little root!
Again, 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 had identified 10% of soil microbe species and by the time she finished this number had been revised to 0.1%!
Here's a simplified description of plant roots and a dominant biological mechanism that works with these roots. It basically works like this: Plants in need of nutrients that they can't easily obtain feed mycorrhizal fungi with root exudates, sugary substances that the fungi like to eat! The fungi in turn, through their tube-like structures called hyphae, deliver whatever the plant “asks” for. 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 diversity is essential!
The point of all this is that plants and microbes all work together to get what they need. The plant eats, the fungi eats, and often, bacteria play a role in this dance and they eat too! When there's enough diversity in the soil and plant life, this arrangement works very well and the kinds of fertilizer and pesticides normally used in agriculture become less important and 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!
Putting it together: Healthy soil reduces runoff and fertilizer needs.
What happens if we put the first two concepts together? Where soil health has been prioritized, we have less water leaving an area. The water that does flow out does so in a way that tends to be slow and steady, its kinetic energy absorbed through the soil profiles. There's little, if any, run-off. Second, the quantities of fertilizers and pesticides can, and should, be reduced once soil microbes perform the functions nature's designed them for.
Farm inputs that kill life or are used as an attempt to directly supply plants with nutrients usually aren't good for soil life, neutral at best. 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 whole living support system the web of life begins to collapse and degrade.
By putting these concepts together we have less water leaving with less “stuff” in it that's detrimental to the places 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 of it rendered harmless, and less leaving. 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.
Maybe someday soon the river that runs through my backyard will flow a litter clearer, carrying bit less of Minnesota's valuable topsoil down to Lake Pepin.
To learn more about soil health and the power of working with nature reach out to Scott by emailing firstname.lastname@example.org. And you can follow his two farm pages on Facebook; Haase Family Farms and Blue Dirt.