Dakota Farmer

Building organic matter has multiple benefits for growers.

Kevin Schulz, Editor

August 29, 2022

5 Min Read
Hand holding soil
LOOK DEEP: To get a true picture of healthy soil, farmers need to look deeper than what the naked eye reveals. Soil tests give producers a better understanding of just what exactly the soil has, or maybe more importantly, what the soil is lacking. Kevin Schulz

Soil tests provide farmers a lot of information, but what does that information mean?

Brian Hefty, CEO of Hefty Seed Co., said at a recent Ag Ph.D. Field Day that the first number producers should look at on a soil analysis is pH, with a number between 6.3 and 6.8.

And more often than not, soil pH does not fall in that range, according to senior agronomist Rob Fritz at Hefty Seed.

“You find out that pH is just a symptom of whatever else is happening in your soil, but it’s still important, and it’s No. 1 on our list for a reason,” Fritz said. “Because if you notice it, it’s going to tell you if you’re too low, you have a lime problem. And if you’re too high, something else is out of balance.”

Producers with high soil pH levels often look for a quick fix, but Hefty said it’s not that easy. “It’s probably not going to be an immediate change if your pH is high, but are there things we can do? Absolutely. We just have to figure out what’s wrong; what’s caused our pH to go high,” he said. “It could be excess magnesium, could be excess sodium. It’s probably excess of something. And it could also in some cases be that you’re short on something.”

Hefty related a situation in one of their operation’s fields where pH was in the 8s. “We put drain tile in, and we put a whole bunch of potash on to take the base saturation K from really low to up around 4%,” he said. “And you know what happened magically? pH came down. A big cause of the pH being high [was] we had things out of balance, out of ratio in that soil.”

Hefty and Fritz gave field day attendees a quick overview of what they see as the important nutrients and numbers from soil tests, and here are a couple highlights.

Cation exchange capacity

Fritz talked about the importance of cation exchange capacity in determining soil type, as in sandy soil or  heavy clay soil. He explained that CEC shows the type of clay and the amount of clay in the soil’s organic matter. “It’s an indication of the holding capacity that your soil can have to hold nutrients and hold water,” he said.

The higher the number, the higher the holding capacity. The soils at the Hefty operation near Baltic, S.D., have a CEC value of 20, which Hefty said is considered a “heavy” soil.

Hefty stressed the importance of finding a soil’s CEC value; otherwise, farmers can speak of heavy soil or light soil, which can be subjective and relative.

Hefty recalled a conversation he had with a Canadian farmer. The farmer asked Hefty to assess his “light, sandy ground.” However, that “light” soil had a 33 CEC, which caused Hefty to respond, “This isn’t light, sandy soil.” The farmer replied, “No, that’s my light sandy soil. Here’s my heavy soil,” which had a CEC of 41.

Hefty described these soils and their CEC values:

  • light-colored sands, 3 to 5 CEC

  • dark-colored loams and silt loams, 15 to 25 CEC

  • dark-colored silty clay loams and silty clays, 30 to 40 CEC

That’s the reason Hefty said a CEC value is needed to remove subjectivity, as well as giving producers an idea of how much nitrogen their soil can hold. Multiplying a soil’s CEC by 10 equals about the maximum nitrogen a soil can hold.

Organic matter matters

Fritz said organic matter levels on soil tests in recent years have been trending higher, “because of the way we’re tilling. Organic matter has an effect on the CEC, but it also has a really high effect on how much water your soil can hold.”

Hefty said every 1% increase in a soil’s organic matter allows it to hold 4% more water.

Fritz says that while organic matter is an important component of healthy soil, it is also the “smallest piece of the soil that you can actually have. It’s not the residue you’re seeing in the field. It’s not the residue that’s laying on the surface. It’s not even from the stalks. Most of it actually is from the root material as it breaks down.”

Building organic matter is beneficial in more than simply improving soil health. “The fact of the matter is a lot of people want to pay us as farmers to sequester carbon, and how we do that is by building soil organic matter,” Hefty said.

He suggested the steps to building organic matter is to first reduce tillage. No. 2 is to plant crops with lots of roots. “Corn, for example, has five times the root mass of soybeans. You can build soil organic matter much faster with corn than beans, he said.

Applying manure or compost will help build a soil’s organic matter, as will cover crops and some biological products, Hefty said.

While organic matter is good, Hefty reminded farmers that soil organic matter is constantly mineralized. “So we run into people saying, ‘Well, we’ve got all this nitrate that’s ending up in the water. It’s got to be from farmers.’ No, it does not,” he said. “A lot of it is just because the soil is constantly releasing nitrogen year-round. As that soil organic matter breaks down, nitrogen gets released.”

He estimated that for every 1% of organic matter in the soils on the Hefty operation, 20 to 30 pounds of nitrogen get released per year. “We have some soils here that are 5% organic matter, so that’s 100 to 150 pounds of nitrogen that are released every single year.”

About the Author(s)

Kevin Schulz

Editor, The Farmer

Kevin Schulz joined The Farmer as editor in January of 2023, after spending two years as senior staff writer for Dakota Farmer and Nebraska Farmer magazines. Prior to joining these two magazines, he spent six years in a similar capacity with National Hog Farmer. Prior to joining National Hog Farmer, Schulz spent a long career as the editor of The Land magazine, an agricultural-rural life publication based in Mankato, Minn.

During his tenure at The Land, the publication grew from covering 55 Minnesota counties to encompassing the entire state, as well as 30 counties in northern Iowa. Covering all facets of Minnesota and Iowa agriculture, Schulz was able to stay close to his roots as a southern Minnesota farm boy raised on a corn, soybean and hog finishing farm.

One particular area where he stayed close to his roots is working with the FFA organization.

Covering the FFA programs stayed near and dear to his heart, and he has been recognized for such coverage over the years. He has received the Minnesota FFA Communicator of the Year award, was honored with the Minnesota Honorary FFA Degree in 2014 and inducted into the Minnesota FFA Hall of Fame in 2018.

Schulz attended South Dakota State University, majoring in agricultural journalism. He was also a member of Alpha Gamma Rho fraternity and now belongs to its alumni organization.

His family continues to live on a southern Minnesota farm near where he grew up. He and his wife, Carol, have raised two daughters: Kristi, a 2014 University of Minnesota graduate who is married to Eric Van Otterloo and teaches at Mankato (Minn.) East High School, and Haley, a 2018 graduate of University of Wisconsin-River Falls. She is married to John Peake and teaches in Hayward, Wis. 

When not covering the agriculture industry on behalf of The Farmer's readers, Schulz enjoys spending time traveling with family, making it a quest to reach all 50 states — 47 so far — and three countries. He also enjoys reading, music, photography, playing basketball, and enjoying nature and campfires with friends and family.

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