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Archuleta's mission is to generate understanding about soil health

By Jean Caspers-Simmet
simmet@agrinews.com

Date Modified: 11/21/2012 1:13 PM

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WAVERLY, Iowa —Ray Archuleta is pumped about soil.

The conservation agronomist with the Natural Resources Conservation Service in Greensboro, N.C., Archuleta spoke about soil health last month at the Waverly Civic Center.

He changed thinking about soils when his Idaho neighbor couldn't afford to bring his son into the operation. The neighbor had good land and access to water, but his labor and input costs were $300,000.

"He had to sell part of the farm, and I could not help him," Archuleta said. "After eight years of college, I did not have an understanding of how soils function. I've learned more in the last five years from talking to farmers, reading the right books and having proper context."

He uses a slake test and a mini-rain simulator to show how healthy soil functions. He took soils from various farming systems in Iowa and North Carolina and had audience members drop them into columns of water. Soil from a conventionally tilled field quickly slaked apart. Soil recently converted to no-till held together better. Soil from an organic farm that used tillage also fell apart.

Soil from a field that hadn't been tilled in 40 years and received its fertility from manure and a diverse mix of cover crops held firm.

"The bacteria, fungus and earthworms in the soil, all these organisms create the biotic glues that hold soil together and help complete the water cycle," Archuleta said. "This soil has millions of tiny pores. It has porosity which allows infiltration. Our country does not have a runoff problem, it has an infiltration problem."

He demonstrated the infiltration capacity of healthy soil with a mini-rain simulator. With the no-till soil, water infiltrated. In the conventionally tilled soil, water stood on top of the soil. On the land, the water and costly inputs would run off.

"When you till soil, you open the aggregates and expose it to copiotrophic bacteria that eat the biotic glues, and the particles no longer hold up," Archuleta said. "They collapse and seal the soil surface."

In nature the soil is never bare, Archuleta said. Too many of the nation's soils are "naked, hungry, thirsty and running a fever."

"We need to mimic nature and nature does not till," Archuleta said.

The soil is a series of spheres functioning together — the earthworms, the pores, the residue, the aggregates and the roots.

Living roots release many types of organic materials. Earthworms are the soil engineers redistributing plant littler throughout the soil profile and increasing water infiltration. Residue provides food for all the "critters" in the soil. The soil pores are the lungs and circulatory system of the soil.

Healthy soil has high organic matter, high infiltration and porosity, high soil organism diversity and biomass, Archuleta said. It requires low inputs, has higher drought tolerance and low weed and pest problems.

Archuleta said he has learned from farmers like Ray Styer from North Carolina, Dave Brandt from Ohio and Paul and Gabe Brown from North Dakota. They have no-till systems and make use of a diverse mix cover crops. Some also use manure and mob grazing.