After a year without in-person events, Green Cover Seed held their first Southeast Kansas Soil Health Conference at their new Iola location on March 5 and 6. Soil health specialist Doug Peterson provided attendees with information on how to improve their fields through his presentation on on soil health priciples and creating better soil function.
Water absorption is key
Water absorption is the most important factor to consider when it comes to soil health, Peterson said.
“Water can't flow through a solid, right?” Peterson said. “Water flows through the pore spaces and voids in the soil - in the open spaces.”
These open spaces are formed when soil has high aggregate stability, meaning it is able to withstand the pressure of water.
“We’re taught that compaction comes from equipment,” Peterson said. “But when it rains, we can get compaction, not from equipment or hoof traffic, but from a lack of aggregate stability. The soil isn’t able to hold it’s shape.”
Once compaction occurs, a field is no longer able to retain water from rain, while a field with strong aggregates will have “tremendous water holding capacity,” Peterson said. For some, tilling may be the first line of defense against issues in the soil, but Peterson would disagree.
“I would submit to you that the reason we believe that tillage can fix everything is because for generations we’ve been tilling soil that had high organic matter, high biological activity and high aggregate stability,” Peterson said. “Tilling the soil for a couple years in a long term rotation and letting it regenerate is much different than tilling soil for decades.”
Instead of tilling, Peterson suggests producers focus on two ways to build aggregates in their soil: biotic glues and exudates from plant roots.
“A really simple biotic glue to understand is the earthworm,” Peterson said. “The earthworm has secretions on his body, so when he makes a burrow it glues that soil in place, so that he doesn't have to expend energy to go up or down that burrow in the future.”
Fungi in the soil also produce a biotic glue in order to withstand the forces of rain water, creating more stability within the soil. Plant root exudates, which plants will create when in need of nutrients, also help create soil structure.
“Plants will give that energy up to attract biology because they know the biology will bring them more nutrients,” Peterson said. “It’s a very beneficial relationship for those organisms. But the secondary benefit of that exudate process is it begins to stick those soil particles together.”
Peterson said when determining a field’s soil health, his first test is collecting some soil in a test tube and seeing how well it can hold up to water.
“That's going to tell me more than all the soil tests combined,” Peterson said. “If it's got good aggregate stability, I know it can hold water. If it can hold water, I know it can probably hold nutrients. If I know it can do that, then I know it can do all the other things that we want.”
Peterson outlined six principles that are vital to improving soil health: context, minimizing disturbance, maximizing armor, plant diversity, continuous living roots and integrating livestock.
Context summarizes where soil is located and how it’s taken care of. It can include ecological factors, such as the environmental constraints, community factors, such as family or landowner involvement, and financial factors, such as assets and budgets.
“The goal is to start improving soil and not go broke right off the bat,” Peterson said. “Sustainability for our land also means financial stability. We have to stay in business to keep improving the land.
Physical disturbances to soil can be a main cause of compaction, as it compresses the aggregates within the soil.
“Any tillage we do crushes those aggregates physically and simplifies soil fauna over time, especially the fungi,” Peterson said. “If fungi are one of the primary sources of biotic glue, when we have less fungi we have less glue. And when we have less glue we have soil that collapses more. That collapse directly impacts water infiltration.”
Peterson said a no till system is the beginning of soil health.
“The future is going to be biofuels, without a doubt,” Peterson said. “Planting a cash crop into a green, living cover crop is the system that mimics our natural systems."
Chemical disturbances can also negatively affect soil health.
“Plants are in control. Plants leak out exudates to attract organisms when they need nutrients.” Peterson said. “When we go into a system like that and add fertilizer, plants will give off less exudates. So with added fertilizer we get a reduction in mycorrhizal fungi.”
Understanding the secondary consequences of adding chemicals is key to understanding how producers are impacting their soil health.
Ground cover is key to helping regulate soil temperatures which in turn can improve soil’s water absorption.
“As soil temperature goes up, the ability of soil to hold water goes down. The water starts evaporating,” Peterson said.
Cover crops can also act as weed control by stopping weed seeds from germinating by blocking sunlight available to them.
“Controlling weeds isn't about knowing what chemical to spray on them after they come up.” Peterson said. “Controlling weeds is about understanding how to keep them from germinating through understanding plant succession.”
Peterson said producers can provide their soil with a balanced diet of sorts by having a year round rotation of plants.
“This is the future,” Peterson said. “A balanced diet year round. Having cash crops in with a diverse cover crop underneath it all the time.”
This is true for grasslands as well, Peterson said.
“High intensity, short duration, very diverse communities have way better water infiltration,” Peterson said. “Diverse communities in our grasslands is the answer to infiltration.”
Having diverse management practices, such as diversifying short and long grazing periods, is also important. Peterson suggests avoiding the habit of managing a field the same every year.
Continuous Living Roots
Living roots are vital to soil health because the exudates from these roots are the number one source of nutrients for organisms living in the soil.
“Roots fix soil,” Peterson said. “You want to build organic matter? Put a root in it. You want to break up compaction? Put a root in it. You want to hold on to nutrients? Put a root in it. Any improvements to the soil can be made by introducing a root.”
Peterson said with traditional practices, a living root is only present in the soil for a set amount of time. With rotational cover crops, nutrients for the soil can be stored and soil health improved.
Across the globe, the best soil comes from where livestock has been grazed, Peterson said.
“That’s what we should be trying to mimic on our grazeland and our crop land,” Peterson said. “We know those livestock add biology to the soil.”
Livestock can also increase carbon in the soil, something that has steadily been removed over years of traditional practice.
“We started out with some pretty incredible land when this country was settled.” Peterson said. “We harvested that equity. Agriculture has been a mining operation. It removed carbon and diversity in the form of profit.”
Traditional farming practices have led to land degradation and environmental issues, leaving many producers struggling to make profits, Peterson said.
“The cool thing is we can change that,” Peterson said. “But it’s going to take some energy to get that equity back. It’s going to take some human energy and it’s going to take some thinking to do that.”