The Highlights: Kris Nichols at the South Dakota 2023 Soil Health Conference
The South Dakota Soil Health Coalition, a nonprofit organization led by farmers and producers, held their annual Soil Health Conference last January. The conference invites students, business professionals, producers, and community members to learn about soil science and the importance of healthy soils. As a keynote speaker, Dr. Kris Nichols gave a presentation about decision making tools for soil health.
At the beginning of her talk, Kris alluded to the audience experience at conferences such as this one. When you come home from a conference, she explained, you might have some ideas you want to implement or several plans that keep changing. But this isn’t a bad thing: plans should be flexible and iterative, changing in response to the situation.
Regenerative agriculture can be like this too. The weather and environment doesn’t stick to rules or a firm schedule. Neither does the science: it changes, it reevaluates, it discovers new ideas. Likewise, there are no rules in regenerative agriculture that a producer must follow to be certified or international standards that miss out on local nuance.
“You have options and opportunities that are almost limitless,” she said, which can be both welcome and scary at the same time. So where do you start?
Here are the highlights from her presentation and practical tools for making decisions.
Nothing is free
Soil is an economy of carbon: for a healthy ecosystem, carbon needs to flow through different elements and be transformed by organisms and natural processes. The core of regenerative agriculture is to regenerate soil through recarbonization. That is, restarting a stalled economy by adding carbon back into the system.
However, as Kris said, nothing is free. Within the concept of “carbonomics,” producers are essentially paying microorganisms with carbon (through the root exudates from the plant) for the nutrients that they supply.
Carbon isn’t infinite – if you want to allocate more carbon belowground, that’s less carbon that can be used aboveground. Many producers are concerned that allocating carbon belowground means they have to sacrifice yield, Kris explained.
But if the soil is managed right, it doesn’t have to be a sacrifice. We need to maximize the photosynthetic capacity of plants in order to balance the underground and aboveground allocation of carbon, maintaining yield and revenue.
“We focus a lot on short-term gains but that gives us long-term losses,” she said, referring to the practice of prioritizing yield without considering soil health.
Her recommendation? To focus on short-term balances and long-term gains.
Except for sunlight, that is
Photosynthesis is the most efficient form of solar to chemical energy conversion, Kris explained. And if our goal of recarbonizing the soil is only possible through photosynthesis, then we want to maximize the amount of time that plants are green and growing.
Because, as Kris said, sunlight is free. Unlike carbon, nutrients, seeds, fuel, or our time.
She recommends a minimum of 280 days a year of growing green, photosynthesizing plants. Even in South Dakota, not so far away from Alberta, this is possible. Producers need to choose frost-tolerant plants as cover crops to ensure that the plants remain productive when the cold winter months arrive; making use of warm chinooks can help keep plants such as turnips, radishes, rye, and canola alive. Some studies have even shown, said Kris, that some plants are able to photosynthesize beneath a cover of snow.
Stretching out the growing season is critical for the survival of soil microorganisms. “In a heaping teaspoon of healthy soil, you can have more microorganisms than the number of people on planet earth,” Kris said. “And they are all hungry.”
Microorganisms aren’t suited to feast and famine periods; they require a consistent supply of soil carbon throughout the year. And the best way to keep them fed is to have living roots depositing carbon into the soil for as many days as possible.
Birds, bats and insects
How do you optimize the capacity of your farm ecosystem?
Producers might choose to plant flowers that attract pollinators or set up bat and bird houses. These animals are underrated pollinators on a farm; Kris explains that more pollen from grass species is found in the digestive systems of pollinators than that of flowers. Farmers can also set up insectaries to attract beneficial insects.
Kris explained a study that involved growing plants around the perimeter of a crop field to attract plant pest insects, drawing them away from the crops. The researchers added a strip of plants within that perimeter to attract insect predators; these insects helped to reduce the pest population. This study demonstrated a unique way to use valuable space and manage pests without pesticides.
This is what Kris means by “eco-function intensification” – considering every square foot of the farmscape and ensuring that it is managed as a healthy, thriving ecosystem.
A moderate amount of stress to plants can make the soil healthier. Referring to the sixth soil health principle of integrating livestock, Kris explained how the unique grazing of cattle enhances ecosystem health.
When an animal grazes, they are injuring the plant’s tissues. To protect the wound, the plant produces biomolecules like antioxidants and polyphenolics, chemicals that are already created normally to guard against damage from solar radiation. The plant requires extra nutrients (she lists the elements of nitrogen, phosphorus, potassium, copper, zinc, and molybdenum as examples) to create these chemicals, so it sends down carbon in the form of root exudates. The soil microorganisms supply the plant with the nutrients it needs.
Unlike sheep and horses, who cut and tear leaves while grazing, cattle graze by wrapping their tongue around the forage and tugging on the plants. This motion applies stress to the roots and causes some root hairs to break off, leaking carbon into the soil.
These two processes – injured plant tissues and pulled roots – lead to more carbon being stored underground, improving soil health and providing food for microorganisms.
Let’s get the audience involved
Halfway through the talk, Kris invited four audience members up to the stage. She gave them two shallow plastic containers with a sponge, representing porous and compacted soil, and filled them with water. The volunteers were invited to hold each wet sponge over a cup and let the water drip out without squeezing it. This is gravitational water, Kris explained: soil moisture that drains downwards, away from the reach of plant roots. Soil with larger pore spaces is prone to this gravitational flow.
She invited the volunteers to squeeze the sponges into a different cup. What comes out is the water holding capacity, or the maximum amount of water that is available to plants. “What we have here is illustrating the power of porosity,” Kris said.
The results: the highly porous sponge produced a fair amount of gravitational water and filled the water holding capacity cup by about a third to a half. The low porosity sponge produced a small amount of gravitational water and, with a nearly empty cup, showed almost no water holding capacity at all. In porous soil, she explained, some water will inevitably drain out. But with minimal infiltration in compacted soil, there won’t be any water available to the plants. You need porosity in your soils to ensure that plants have an adequate and consistent supply of water.
Choosing your tools
The question, said Kris, isn’t whether you should use a certain tool or practice, but why – taking into account the positive and negative consequences and how to use the practice most effectively.
Sometimes that means you’ll have to till or disturb the soil to control weeds, even if you’d prefer not to. But what you can do is reduce the damage as much as possible and think about ways to help the soil recover. You might alternatively choose to use animals as a form of soil disturbance: their hooves gently break up the soil and control weeds without causing excess damage. And anyways, she explained, the soil can tolerate some disturbance; soils in natural ecosystems deal with animals, flooding and wind and remain functional and resilient.
Kris uses the FIST acronym to explain the nuance of tool use: frequency, intensity, scale, and timing. If you use a split application of fertilizer, you will need to apply it more frequently. But that isn’t necessarily a bad thing, she adds. You might choose to apply it as the plants are going into their reproductive phase, which is when they need the most amount of nutrients.
The intensity of a tool can make a difference. Applying a large amount of readily available nutrients might be appropriate in one context, but other times you might want to apply nutrients in an organic form so that they are released gradually. As for scale, producers might consider the volume of soil that is disturbed by a certain tool, like a plow, or the quantity of nutrients to apply.
Considering the timing of seeding, producers may choose to plant seeds before a soybean cover crop senesces and drops their leaves (senescence occurs when a plant’s cells stop growing and dividing due to aging). The leaves will protect the seeds and allow them to germinate without experiencing damage from solar radiation.
And above all, “it’s not about bad or good, it’s about looking at the consequences of the tools that you’re using.”
See the full recording here: 2023 Soil Health Conference: Kris Nichols - Soil Context as a Decision Tool - YouTube
Article by Food Water Wellness, http://www.foodwaterwellness.org/