Healthy soils: Importance of soil organic matter for improving soil health explained

The Oct. 29 edition of the Healthy Soils Webinar hosted by the Powder River Basin Resource Council featured University of Wyoming Northwest Area Agricultural Extension Educator Dr. Caitlyn Youngquist. The presentation explained the composition of healthy soils and explored how they can lead to more productive fields, rangelands and gardens. 

Soil health

                  Youngquist explains the dictionary definition of health includes the capacity to function, which she relates to soil health. 

                  “In terms of soil health, a healthy soil is a highly functioning soil,” she says. “In terms of plant, animal and human health, the definition also includes biological productivity and environmental quality.” 

                  Resiliency, the ability to withstand or recover from difficult situations such as drought, compaction, erosion and disease, is an important part of building soil health, she adds. Another important consideration she explains is soil health as a spectrum. 

                  “The idea is to continually move along the spectrum, from less healthy to more healthy,” Youngquist shares. “Healthier plants, more water holding capacity, lower input costs and erosion resistance can be attained through management and monitoring.” 

Soil systems

                  Youngquist explains soil is a thin crust of old rock and organic matter on the earth’s surface, as well as a living system of plants, insects and microorganisms. 

                  “The first part of the definition is inherent, while the second part, the living part, is dynamic and where soil managers can have an impact,” she explains.

                  “Five different factors go into forming soil,” she continues. “The factors deal with where on the landscape the soil is, how old it is, the climate and the parent material. Understanding how the soil is formed is important to understanding why the soil behaves the way it does.” 

                  Another way Youngquist notes producers can think about the soil system is to consider soil as a system of chemistry, biology and physics. Chemical components of soil include pH and salts, nitrogen, phosphorus and potassium, carbon and micronutrients, while the biological component consists of crop condition, disease pressure, earthworms and carbon, Youngquist says. The physical component is erosion, compaction, infiltration and tilth. 

                  “Modern agriculture is very good at the physics and chemistry parts of soil, but we are learning more about the biological system,” she says. 

Biological activity

                  The whole system is driven by photosynthesis, Youngquist shares. 

                  “Starting with the plant roots, plants take carbon out of the air and put it into the soil as organic matter which feeds the biological system of the soil,” she notes. “There is a tremendous amount of activity in the soil.” 

                  Youngquist explains soil contains bacteria, fungi and nematodes, as well as larger organisms. 

                  “A lot of the nutrients in soil are not available to plants until the soil is digested by the small organisms in the soil,” she says. 

                  Increasing the amount of photosynthetic activity, or the amount of healthy plants living in the soil, feeds more microorganisms in the soil and therefore, increases the pool of soil organic matter, Youngquist explains. Decreasing the amount of disturbance also helps to increase the organic matter pool. 

Organic matter

                  In Wyoming, soil organic carbon or organic matter levels range from less than one percent to around two to three percent in the eastern part of the state, says Youngquist. 

                  “The most important thing to do for soil management is increase the quantity, diversity and duration of living roots to add to soil health, as well as reduce disturbance,” she says. 

                  “In the Big Horn Basin, producers grow a lot of sugarbeets,” she continues. “Inherently, it is hard to have an undisturbed system while growing sugarbeets. We have a highly disturbed system in the basin, but there are a few producers working on a couple different methods to decrease soil disturbance.” 

                  She notes field observations, as well as laboratory tests, either at the garden scale or on a larger scale like pastures or crop fields, are very important. However, Youngquist says, the most important thing a producer can do is to look at the texture, rooting depth and be observant of things like erosion. 

                  “The take home message is to get the carbon in the soil and keep it there,” she says. “Plant roots, compost, manure and mulch all add carbon and increase soil organic matter. Things like tillage, bare soil and erosion deplete soil organic matter levels.” 

                  Averi Hales is the editor of the Wyoming Livestock Roundup. Send comments on this article to roundup@wylr.net.