There is a growing movement and awareness around the need to use regenerative soil practices as a way to mitigate climate change impacts and to conserve water. A recent forum at the Altona Grange hosted by MAD agriculture brought together scientists and farmers to discuss regenerative soil practices.
Two of those in attendance were soil scientist Clark Harshbarger and Longmont farmer Rod Brueske. Brueske has been using regenerative practices to improve soil health on his farm.
The soil on the left is healthy and fertile after a regenerative process
l-r Rod Brueske, Clark Harshbarger
Clark Harshbarger, a soil scientist with the USDA Natural Resources Conservation Service in Greeley, says there are 4 principles to healthy soil:
Keep the Soil Covered
Exposure to direct sunlight, especially in our warm summer months will increase temperatures in the top soil and on the soil surface that are not optimal for most soil life. Just like humans, soil life flourishes at around 60-80° F. Starting at around 100°F, soil food web species will begin to function less optimally and at temperatures of 140° F, most bacteria, fungi, protozoa, and insects will not be able to live in the soils. You can use compost, straw, and last year’s dead plant material to armor the soil. Residues also feed earthworms, as seen in figure 2. The worms then deposit the plant material in their castings, back into the soil which makes the nutrients available for other soil food web organisms and plants.
Disturb the Soil as Little as Possible
We cannot engineer or create a habitat for the soil food web as well as Mother Nature. So it is imperative we leave her to do her work. When we till our soils these habitats get disturbed and the soils are exposed to excess oxygen which over stimulates the soil bacteria putting the soil food web out of balance. When exposed to excess oxygen, bacteria digest available forms of carbon at higher rates depleting the soil of its food source all at once, leaving it less fertile for the remainder of the growing season.
Diversify What is Grown
Just like us, the soil food web needs a diverse diet to stay healthy. Plants have unique enzymes that work with different organisms in the food web. Some species form symbiotic relationships with fungi, called mycorrhiza that can even help feed the plant directly into the roots by mining nutrients from minerals and transporting soil water directly into the root. Also, different plants have different ratios of carbon such as cellulose, hemicellulose, and lignin, each providing a source of food that is digestible by different portions of the soil food web. Companion planting, and using grasses, forbs and legumes along with cool and warm season plants will ensure diversity in your garden, landscape or cropping system.
Keeping a Living Root
By keeping the plants alive in our soils throughout the growing season, we continue to nurture the soil food web with a food source. Most soil organisms are like humans, in that they need food, water and oxygen to survive. Plants help provide essential food for the soil food web in the form of exudates, such as carbohydrates, water soluble vitamins, organic, nucleic, and amino acids. Excretions from fungal hyphae called glomalin and the other soil exudates help aggregate soil particles together to provide both habitat and a food source for the life in soil. Additionally increase water storage which benefits both the plants and soil life. Using cover crops or biological primers during all times of the growing season is one practice that can be used to keep a living root to feed the soil all year long. To learn more about the soil food web please visit the International Years of Soils website. https://www.soils.org/iys/12-month-resources/july