The Change Exchange discussion group the last couple of months have focused on the life under our feet. This month we bring it all together and explore how soil can improve our lives. The documentary “The Symphony of the Soil” starts by describing the geological processes that form the sand, silt, and clay that make up the parent material of our soil. From these materials all life begins.
One of the simplest soil tests you can do is the jar soil texture test. To do this test, simply gather several representative soil samples from a field, mixing it up and then put a cup or two in a jar. Add water and shake. As the soil settles, the heavier material, gravel and sand, will fall out first, followed by the lighter silt, then after a day or two the clay will settle. This gives your soil texture.
Images: USDA
Soil texture is one of the most common challenges in agriculture. Often soil is too heavy, causing poor aeration and water infiltration. Or, it is sandy, and susceptible to drought. The good news is that an active vital living ecosystem mitigates the issues related to all soil textures. If your soil is heavy, soil organisms will improve soil structure and improve aeration and water infiltration. If your soil is sandy, soil life increases soil organic matter, increasing water holding capacity and nutrient availability to plants.
But sand, silt, and clay alone don't support plant growth. Without biology nutrients stay tied up in the soil parent material. A complex soil food web is required to provide the biological, chemical and physical characteristics that break down soil parent material; the sand, silt, and clay, and convert it to a form plants can use.
This soil food web can also extract nutrients from air, such as nitrogen, and fix it in the soil profile for future plant growth. Nitrogen is one of the most important nutrients plants need, and it is incredibly abundant, making up some 78 percent of our atmosphere. There is estimated to be 34,000 tons of atmospheric nitrogen above every acre of planet earth. Our challenge in agriculture is how to make 200 pounds of that available to our crops annually.
The soil health principles protect and restore the vital living ecosystem that cycles nutrients and make them available to plants. Farmers implementing these on row crop acres are maintaining yields and increasing economic return. But what about marginal lands not well suited to row crop agriculture?
Forests are places of wonder and inspiration and often seen as the solution to environmental issues. They are complex, starting from early successional stage after some type of disturbance, such as fire, wind, or human action, and progressing to a climax “old growth” forest, often revered for the special places they are. But for most of our landscapes, old growth forests are not consistent with historic patterns. While late successional stages like old growth forests tend to decline in diversity and productivity, disturbance brings plant communities back to an earlier successional stage increasing growth and diversity.
Where logging is now the primary method of disturbance in our forests, once fire and grazing ruminants were the primary disturbances for much of the Midwestern landscape, particularly the prairies and the savannas which fluctuated between the prairie and forest ecosystems. Native Americans used fire to shape the landscape. They used fire as a tool for hunting big game, and used fire to set back forest succession and encourage the growth of fruit and nut producing brambles, shrubs and trees.
Fauna thrived on this disturbance; from countless soil organisms like dung beetles and other insects, to billions of passenger pigeons and waterfowl, and millions of large grazing herbivores, all flourished on this landscape kept in an early successional state through fire and animal impact.
It was these systems that built our most abundant and fertile ecosystems. How can we mimic these complex ecological systems in a landscape now crossed with roads, agricultural fields, and urban development? While we can’t realistically replicate them, there are some broad concepts that can help.
Agroforestry is defined as the intentional integration of trees and shrubs into crop and animal farming systems to create environmental, economic, and social benefits. These systems mimic early successional plant communities promoted by indigenous people.
Reincorporating fire into fire dependent plant communities makes ecological sense. This practice can be challenging due to threats to human built infrastructure, but when properly implemented fuels growth and diversity. Burn Patch Graze is a system where planned burns and grazing are implemented in a rotation to encourage new plant growth favorable to ruminants. It is being used successfully in large scale restoration efforts, primarily on public lands, and has been proven to have broad ecological benefits including increased plant diversity, habitat restoration, carbon sequestration, and improved soil health.
By matching farm production and farming systems to the ecological context of the landscape we can provide the food we need as a society and restore the ecological balance which has been lost by forcing inappropriate practices onto the land. As farmers we need to embrace this concept. As consumers we need to understand the challenges the farmers face in adopting these practices, support them through our purchasing priorities, and encourage policymakers to support these efforts.
Would you like to learn more about the ideas in this blog post? Whether you are an experienced grower, a newbie gardener and/or someone who cares a lot about the food you eat, come share your ideas and questions at Change Exchange, the monthly discussion group that tackles complex issues around sustainability. Currently meeting on Zoom, the goal of the group is to share concerns and solutions. Additional resources are available to watch, read or listen to before the meeting, but “homework” is optional. Learn more here.