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How to Build Organic Matter

Proper field management can boost crop yields.

Management steps like tiling and using cover crops that boost soil health can either help or ding crop yields. Dave Legvold, Northfield, Minnesota, found this delicate balance when he took over the management of a farm near his operation 13 years ago.

The land he rented was heavily tilled and poorly drained. Legvold, a strip-till advocate, wanted to improve the field’s overall health. He implemented steps that increased the field’s organic matter from 1.7% up to 5.5% and even 6.5% in parts of it.

“The more organic matter we can have, the better off we are,” says Chad Watts, executive director of the Conservation Technology Information Center.

“All soil is different,” says Watts. “We have to treat it differently in a case-by-case situation.” As a general rule, Watts suggests less physical disturbance and more plant diversity.

The soil receives a lot of benefits from organic matter, says Watts. Tile and healthy soil enhance one another’s properties.

“You can make the tile more efficient with a healthy soil because you’re able to move that air and water a little more effectively,” he says.

Improved field drainage

Legvold’s first step was to improve field drainage.  

“It was horrible,” says Legvold. “The previous operator was able to deal with the strange hydrology by moldboard plowing and then making a couple cultivator passes in the fall.”

Moisture can limit soils, says Watts. “There’s really productive land that needs to be tiled,” he says. “It allows us to make soils more productive.”
By adding field drainage, Legvold can enter the field sooner. “I’m not waiting for soaked puddles to dry out,” he says.

Drainage, if used properly, is part of the farming system, says Watts. Reduced tillage is the next step in Legvold’s equation. Tillage incorporates the organic matter and causes volatilization. This causes organic matter to burn up and convert into atmospheric carbon, says Legvold.

Breaking down tillage

Tillage injects air into the soil, says Watts. In the fall, when air leaves the soil, tillage is again needed. It’s not a healthy cycle. The more tillage you do, the more tillage is needed, he says.

“Fifty percent of the soil should consist of air and water, while the other 50% should consist of soil material,” says Watts.

“If it’s 75% soil material, you don’t have enough pore space to move the air and water. As you create the pore spaces, you get more ability to move it,” he says.

“I know water is going to soak into the soil instead of running off the top,” says Legvold. He also doesn’t need to roll his land, because he doesn’t worry about soil-to-seed contact.

Although Watts wants to see less soil disturbance, he doesn’t say every acre should be no-till. “There are management techniques that have to happen on different soils, but there are a lot of places we could use no-till,”he says.

Immediately after transitioning, soils may not be efficient at moving air and water. With fewer disturbances, you will improve the drainage of the soil, as well, says Legvold.

“If you’re patient and allow your soil to develop, you’ll form good aggregate stability,” he says. “I’ve been able to go out in the field with the planter because the soil is solid at times when other people aren’t able to.”

Increasing Yields

“The yields have been increasing as the soil gets better,” says Legvold. It’s also helped Legvold’s nutrient plan. Besides placing the nutrients by the roots, he also sees benefits from the soil.

“In the past, I had to pour a lot of fertilizer on it to get it to produce,” he says.  

Now that he’s improved the overall field health, he’s able to rely on the soil-cycling nutrients and use up to 30% less fertilizer. Cover crops are another practice that can help the process of building organic matter, improving soil health, and improving fertility, says Watts.

Improved soil health

“With the addition of cover crops, over time it might change the way we think about our nutrient strategy,” says Watts.

There’s the potential to cut back on nutrient inputs, but it’s not going to be immediate, he adds.

Legvold has been able to save fuel. With reduced tillage and less nutrient needs, he’s able to make fewer passes across the field throughout the season.

“There is a phenomenon of masking productivity loss due to declining soil quality with improved genetics, better fertilizer management, better pest control, and better technology,” says Legvold. “If soil quality continues to decline due to tillage we will soon reach a point where we cannot overcome productivity loss no matter the strategy.”

“Nothing we do on the farm happens inside its own box,” says Watts.

Every management practice has implications associated with it. “It’s a domino effect,” says Watts. “That’s why we have to make changes incrementally using a systems approach that encourages all of the parts of the farm to adapt and work together.”

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