The Agronomy of Improving Soil Health with OSU’s Dr. Brian Arnall

At the Women in Agriculture Conference, Farm Director KC Sheperd spoke with OSU Professor Plant & Soil Science and Extension Specialist Dr. Brian Arnall about soil health and crop resiliency.

Arnall said that his definition of soil health begins with where the soil is at in terms of structure, its ability to resist weather extremes including both drought and flooding, and its ability to grow a crop, both economically and environmentally within a sustainable realm. Steps to soil health include increasing organic matter, and in effect, carbon in the soil, thus changing the structure of the soil which will allow for better water retention and more microbial and fungal activity to increase soil diversity.

Dr, Arnall said the soil in Oklahoma is nearly as varied as it gets and what works in one part of Oklahoma may not work in another. “We go from ‘gators to antelope all in one state, and there’s not many states that can say that,” he said. “Every soil is different – we have rainfall, we have how the soil was formed – but even within a farm, you have different soils. You have the side slopes, the bottoms, the good ground, the poor ground, and the eroded ground. We have the clay soils in Ottawa County, we have the red soils in the middle and in the high plains. Maybe we need more cover crop for carbon and soil stability on a slide slope, but our bottom ground needs something that increases water infiltration depth, so maybe a deep -rooted tap crop or a rotation that helps our roots go deeper.”

Dr. Arnall said that farmers looking to improve their own farm’s soil health need to ask themselves some questions: What is your end goal? What is your capability? Are you willing to stop and plan out chemical rotation, crop rotation, and implement rotation, because building soil health takes time?

“The starting point is the soil test. Know where you are at. Is your pH okay? Is your phosphorus and potassium at good levels, because if not, those things need to be fixed before we go into any major implementation,” he said.

While no-till is a common practice for people focused on soil conservation, Dr. Arnall says that it does have a place. “We have areas in Eastern Oklahoma. If they want to plant corn, they are no-till up until their corn crop. It’s cool. It’s wet. It’s heavy clay. They need to get a little bit of ground to open up for it to dry and to warm. So they do tillage in front of corn – looking at strip till, there.

“Also, we are looking at other properties that have been no till for 20- to 30-years, and we are having to evaluate do we get in there and do a tillage event because we have so many seeds and so much nutrient stratification. We may do an inversion tillage and come it with a cover crop immediately, which buries that wees see that’s got all of the chemical resistance. It puts a nutrient rich layer that is six or eight inches down, and then stabilizes the top of the soil. We kind of have a fresh start going in there.”

Depth of soil is the most difficult thing to improve, and nearly impossible. He said, “When you have a shallow soil, a lot of the soil health and regenerative ag is intensifying how many plants we have growing. but if we have shallow soil, we can’t hold moisture to support that many plants when we go hot and dry. The challenge is knowing what you land capability is. That deep bottom where you can send a root eight feet deep, we’ve got a lot of capability, but that eroded red hill over in Kingfisher County is a whole other ballgame. It’s a lot more challenging to establish and maintain.”

Dr. Arnall said that producers need to have a five year plan for soil health, but be ready to change it tomorrow. In a perfect world that gets the correct amounts of rainfall and temperature, you have one plan; however, you should have an alternate plan for drought and for flooding which can happen in the same year. He advised to be adaptive and realize that the road to improved soil health isn’t easy.

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