Soil that acts like a sponge provides erosion control

ROSEVILLE, Ill. — Farming organically is a pro-active systems approach that involves more than a set of prohibitive rules.

“This farm has been certified organic since 2009,” said Joel Gruver, associate professor of soil science and sustainable ag at the Allison Farm at Western Illinois University. “The first fields were certified organic in 1997 and that creates the context for everything we do here.”

“Western has managed this farm since 1989,” said Andy Baker, director of the Department of Agriculture at WIU.

“There is no university support for this farm,” said Baker during the Soy Around the State media tour, organized by the Illinois Soybean Association. “This is a self-sustaining farm that has to be able to produce enough revenue to get to the next year.”

An organic systems approach, Gruver said, includes practices that promote good resource management.

“Crop rotations are required, soil prevention practices and you have to look at water quality issues,” he said.

Gruver thinks of soil like a sponge.

“The best approach to erosion control is to have more infiltration so the soil is a better sponge,” he said. “If soil soaks up water so you don’t have runoff, then you have much less erosion.”

If soils are better sponges, then they won’t just prevent erosion, but will also resupply water, Gruver said.

“We have soils that can supply more than a foot of water, which is about two-thirds of what the crop needs,” he said.

Most people think of erosion as a horizontal process as runoff flows over the land.

“Erosion is also a vertical process when particles get detached and fill up the big pores,” Gruver said. “Then you end up with poor infiltration and the sponge effect is lost.”

Soil contains different types of carbon.

“What we want in our soil is a mix — some carbon that’s really stable and sticks around for a long time and also carbon that is the energy for microbial activity,” Gruver said. “The carbon can’t all be old, stable stuff because the microbes won’t get their energy.”

Organic no-till soybeans have been grown on the Allison farm since 2009.

“Almost half of our soybeans are now planted no-till,” Gruver said.

In one field, soybeans were planted into rye.

“The rye was about six feet tall and it had finished blooming and stopped shedding pollen,” Gruver said. “We planted soybeans and rolled the rye down eight days later and now we have a nice, thick mulch and good weed control.”

Other soybean fields are managed with conventional tillage.

“The art of cultivation is not controlling the weeds between the rows — it’s controlling the weeds in the row and that requires more attention to detail,” Gruver said. “Weed control in the row is where you protect your yield.”

This requires more than just cutting off the weeds.

“If you don’t control the in-row weeds with the first cultivation, they will be very resistant to burying,” Gruver said. “The opportunity for controlling in-row weeds with mechanical cultivation is when the weeds are small, flexible and they haven’t been propped up by soil.”

An Accura Flow cultivator is used at the farm.

“Many farmers prefer a tool that that you can set and go, but that is not this tool,” Gruver said. “For example to get good in-row weed control, you have to have the soil flowing differently behind the wheel than other parts of the cultivator.”

The cultivator, which is built by an organic farmer in Iowa, features many parts that are adjustable.

For each field, Gruver makes adjustments to the gauge wheels, stabilizer disks, the height and pitch of the shank and the shields that protect the crop.

“I want to get the shields dialed in just right so the soil is blasting off them, but not overtopping the crop,” he said. “I want the soil to come into the row and make a perfect peak on every row.”

The soybeans are typically cultivated twice.

“We’re growing 70-bushel beans and last year we sold our beans for mid-$30s per bushel,” Gruver said.

Accura Flow cultivators are available in six, eight and 12 rows.

“The tool costs about $4,000 per row,” Gruver said. “Now organic beans are around $40 per bushel, so it doesn’t take many bushels to pay for this tool.”

Farmers may combine cultivation with other technologies such as flaming.

“This cultivator is the foundation of innovative organic farming,” Gruver said.