Soil health 101
“The principles of soil health are simple,” says Frank Gibbs, a soil scientist from Ohio who spent decades with the USDA. “You’ve got to limit soil disturbance, increase soil microbiological diversity, grow living roots year-round, keep the soil covered, and reduce compaction. It is all about management.”
Easy to say, but improving management can take a lot of time, and investment in new equipment as well.
This rainfall simulator captures the water that runs both off the surface and through the sample to show the difference that soil management makes when it comes to soil erosion and water quality.
There are many factors to consider when it comes to soil health. Micro and macro-nutrients need to be balanced and the pH at a good level. It needs good structure and aggregate stability to hold up against wind and water erosion. It needs proper drainage and, at the same time, moisture holding capacity. And the list continues.
Most farmers grew up plowing. Tillage terminates weeds and creates a ‘pulverized’ seed bed and good seed to soil contact for germination. Yet, research is showing us that tillage is the primary cause of soil erosion. With new technology, especially herbicides and no-till planting equipment, farmers are able to get creative in order to minimize tillage.
Principles to build soil health
Farmers build soil in the same way that nature does:
- Limit soil disturbance
- Keep the soil covered
- Grow a diversity of crops
- Apply manure
Methods will vary depending on each farmer’s equipment and opportunities but could include:
- Using cover crops to increase diversity in the crop rotation and keep the soil covered.
- Using strip-tillage to limit soil disturbance and keep the soil covered with residue from the previous years’ crop. (When crop residue is left on the surface, it is the best food for earthworms and microbes. So using cover crops and minimum-tillage in conjunction can get soil humming with life.)
- Using controlled traffic to limit soil disturbance and minimize the areas of the field that are compacted with heavy machinery.
- Growing hay or rotating a field to pasture to keep living perennial roots in the soil.
- Applying manure to add important micro-nutrients (also found in other organic amendments like compost) that will feed microbes that both build soil and hold it together.
How do you know if your soil is on the right track?
- Increasing organic matter: Take soil samples every few years to track your progress.
- Biological activity: When people talk about ‘bringing soils to life,’ they literally mean increasing the amount of living creatures in the soil. You can measure this by counting earthworm holes in a square foot. Another way is to bury a piece of 100% cotton in the top layer of the soil to measure levels of decomposition after a few weeks/months.
- Improved infiltration: You can visually see the improvement of the soil’s ability to let water in and through. Better infiltration rates mean there is less opportunity for rainwater to run along the field surface and pick up soil and nutrients.
- Slake test: This tests the soil’s aggregate stability, basically its ability to hold together. Place a clump of dried soil in water and see if it disintegrates and muddies the water or not.