The Importance of Soil Health

When we discuss water quality in the Eau Claire River watershed, we often talk about “soil health” which, according to the US Department of Agriculture (USDA), can be defined as “the continued capacity of a soil to function as a vital, living ecosystem that sustains plants, animals and humans.”  The term “soil health” is also sometimes interchangeable with the term “regenerative agriculture” when looking at the whole farm and the business of farming. Generally, both these terms focus on trying to make the farm and its fields function more closely to how a natural prairie ecosystem functions.

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If you think about a prairie, it’s never tilled, it never needs weeding or watering, it provides habitat for diverse plants and animals, it functions year after year with no help from humans, etc.  We can’t really make a farm into a perfect mimic of nature, but there are many things we can do to bring it closer to that goal. Again from the USDA, four major management principles can be stated when moving toward a regenerative agriculture system:

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1. Minimize disturbance

2. Maximize soil cover

3. Maximize biodiversity

4. Maximize the presence of roots

 

Minimizing disturbance has several components. A regenerative agriculture system reduces tillage in fields, eventually getting some fields to the point where it is no longer necessary to till them at all.  Tilling tends to kill/destroy the natural community of organisms that live in the soil and destroys the natural structure of the soil, which makes it less capable of holding water.  Less water infiltrates tilled soil and therefore produces more runoff, which carries soil, chemicals and “algae food” like phosphorus and nitrogen into our water bodies.  So, the less runoff coming from a field, the better for our rivers and lakes.

 

Minimizing disturbance also means to reduce the compaction of soil from heavy machinery, and reducing chemical disturbances with pesticides and herbicides. Healthy soil with good structure can hold more water and acts more like a sponge when heavy machinery drives over it, bouncing back rather than leaving huge ruts that cause more problems of their own.  Healthy soil also has a more balanced flora and fauna, which can help protect the soil from the infestation of unwanted organisms such as insects and fungi. Chemical additives to a field tend to kill or greatly disturb these natural communities by killing all organisms, not just the unwanted ones.

 

Maximizing soil cover includes keeping the soil of a field covered as many days of the year as possible with living roots or plant residue. In what could be termed as traditional agricultural methods, a field is often tilled in the spring, planted with a single crop, the crop is harvested in the fall, and the field lays bare and fallow the rest of the year, making the soil susceptible to runoff from heavy rain events or snowmelt and erosion from the blowing wind. Having plants or plant residue on that field more days of the year helps minimize runoff by soaking up more rainfall and having a cover of living (or recently living) material over the top of the soil.  This can be done by planting cover crops such as rye grass or clover in the later part of the growing season (either after harvest or when the cash crop is still growing in the field). This cover crop can stay in the field through fall until snow comes in the winter, and still be covering the soil after melt in the spring, up until the time a new summer crop is planted.

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Another way of maximizing soil cover is to find those parts of a farm field that perhaps are unprofitable to farm; for instance, low-lying areas that are prone to flooding, or areas that have soils that simply do not produce a good yield year after year. Planting such areas to permanent natural plant cover may be an option.

 

Maximizing biodiversity comes as a result of some of the things already mentioned, such as not tilling the soil, and planting cover crops. These practices promote the presence and growth of soil organisms that help balance pH, help store moisture, and help minimize the need for chemicals.  You can also maximize biodiversity by rotating crops in a field and not always planting the same one or two kinds of crops year after year.  Adding grazing crops and livestock to fields also increases biodiversity. Plus, cows grazing in a field add fertilizer (manure) in a natural way, versus gathering manure in a confined animal operation and spreading it on a field all at once.

 

Maximizing the presence of roots helps the soil absorb moisture and provides food for the microbes and diverse organisms that are needed in the soil year-round.  For instance, earthworms, which are valuable for adding organic matter and nutrients to the soil, can use root channels for movement in the soil.  The presence of roots also helps stabilize the soil in times of large rain or runoff events by infiltrating more rain and producing less runoff.

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Establishing these soil health management principles contributes greatly to keeping water where it falls, and allowing it to infiltrate into the ground (replenishing groundwater) rather than running off a field, carrying the farmer’s valuable soil into rivers and lakes, and carrying with it those nutrients that feed algae and bacteria in the water.  Additionally, having soil that is healthier and more resilient to changes and extremes in weather is more profitable and sustainable for the farmer.