NRCS agronomist encourages practices to promote healthy soils in agricultureWritten by Natasha Wheeler
Worland – “Since 1982, we’ve lost about 14 million acres of prime farmland in the U.S.,” remarked Marlon Winger, Idaho state agronomist at USDA National Resources Conservation Service (NRCS), during a presentation on Feb. 19.
Winger used soil aggregate demonstrations to illustrate water infiltration and soil health principles to an audience at WESTI Ag Days, hosted by University of Wyoming Extension in Worland.
“We need to treat the problems of poor soil health instead of treating the symptoms,” he explained.
Soil health is defined by NRCS as the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals and humans.
“We want the soil to cycle nutrients – not to just absorb them, but to cycle them. We want our soil to have good infiltration and availability. We want a good, physically strong, stable and supportive soil,” he remarked.
Winger also emphasized the living ecosystem found within soils, describing microorganisms that need food, water, shelter and habitat to survive.
“We know that management practices can improve or degrade soil health,” he said.
He further described that livestock have a relationship with the belowground ecosystem, and people, animals, plants and the environment are all connected.
“How did our ecosystems flourish without human input?” he asked. “Characteristics of a healthy soil ecosystem are low disturbance, low human inputs, high functionality and fungal-driven systems.”
Soil food web
Winger described how plants, microorganisms and larger organisms such as insects help contribute to the soil food web, which cycles nutrients, creates soil aggregates, infiltrates water and provides habitat.
To illustrate an unhealthy system, he shared a photo of an empty field, void of vegetation or animal life.
“Ray Archuleta says this soil is naked, hungry, thirsty and running a fever,” he noted of the picture.
Without vegetation, the soil is left open to the elements without a form of armor such as plant roots to keep dirt from eroding, and therefore, the soil is naked, Winger said.
“Why does Ray say the soil is hungry? Because there is no photosynthesis currently taking place in this field,” he continued.
Bare ground is also more susceptible to high rates of evaporation, runoff and erosion, meaning that water is limited on the landscape, which could then be described as thirsty.
“In the summertime, the soil runs a fever because it’s hot. There is no armor on the surface. Imagine a knight of the round table going to battle in shorts.” he remarked.
Disturbance of the soil translates to a disturbance of the ecosystem contained within it, which depletes soil health, Winger continued.
“Tillage is the manipulation of the soil for the purposes of managing the previous crop residue or weeds, maybe to incorporate amendments or prepare for planting,” he cited as an example.
But, tillage often destroys soil aggregates, which serve as important habitat for microorganisms while also providing pore spaces for plant roots and water infiltration.
“We thought we had to make this nice seed bed, but by the time we get done, we’ve pulverized that soil. Tillage exposes organic matter to rapid decomposition, it compacts the soil and it damages soil fungus,” he described.
Important mycorrhizal fungi can be damaged, soil pore continuity can be disrupted, surface salinity can increase and weed seeds can be brought up to the surface when tillage is used in a field.
“Growing a single species or few crops in rotation is a form of biological disturbance. A lack of diversity limits diversity of plant root exudates,” Winger continued, describing the exudates as a part of the important “biological glue” that holds soil aggregates together.
Overgrazing is another disturbance that can cause poor soil health if areas are grazed extensively and not provided any periods of rest.
“Plants don’t store energy in their roots. They store it in the bottom three inches of the stem. If we grub it all the way to the ground, we’re taking all the money out of the savings account,” he described.
To create healthy soils, Winger explained that producers should understand how soils work and which elements contribute to a healthy soil ecosystem.
“There are five items we believe can fix poor soils,” he said.
Minimizing soil disturbance, maximizing the diversity of plants in rotation, keeping living roots in the soil as often as possible, keeping the soil covered with vegetative armor and incorporating healthy grazing into farmlands are all methods that producers can use to encourage healthy soils.
“These principles create the best habitat possible for the soil food web,” he said. “Let’s stop treating the symptoms of dysfunctional soil and look to solve the problem of that dysfunctional soil.”