Whole Farm Conservation

September 1, 2015
By LARRY KERSHNER – Farm News news editor ([email protected]) , Farm News

[email protected]

MINBURN – If farmers are going to meet the requirements of the Iowa Nutrient Reduction Strategy, it’s going to take more than one type of conservation farming method.

That’s the message that Liz Juchens, of Iowa Learning Farms, hoped that a dozen farmers took home with them Aug. 5 from the Craig Fleishman Century Farm in Minburn.

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Fleishman hosted a whole-farm conservation field day sponsored by Iowa Learning Farms.

Fleishman called himself Mr. Stacking Guy, because he stacks his field management practices.

Juchens said Fleishman employs a suite of conservation practices – ridge till, extended crop rotations, corn and soybeans planted side-by-side in 12-row strips, and cover crops.

Fleishman said 2015 has been a tough growing season with Story County measuring 21 inches of rain so far this season, about 7 inches in July alone.

Oats, which are his third rotation crop, are more of a challenge than he expected.

“It’s been so long since oats have been grown on this farm,” he said, “we’re learning to do it all over again.”

The small grain did not want to ripen evenly this year, he said, plus with repeated rain storms up until Aug. 5 he finally cut and swathed his oats the previous day, about three weeks behind the rest of Iowa.

He said he’ll sell the oats to a neighbor as cover crop seed and he’s considering selling some of the straw to another neighbor, “although taking the straw off is kind of defeating the purpose,” he said.

Having oats as a third rotation, Fleishman said, is to get a diverse mix of root masses in the soil and for erosion control during fall and spring rains, when there is no commodity crop standing out there.

Fleishman said he’s been ridge-tilling since 1981.

“It’s the forerunner of strip-till,” he said, “only it’s cheaper and I like the raised seed bed.”

He said he’d ideally like to work with a six-row planter, but it’s time-consuming when one has many acres to plant.

He plants his corn, soybean and oat fields in alternating 12-row strips.

“Primarily,” Fleishman said, “the strips are for conservation, slowing water moving across the top and slowing the cutting of ephemeral gullies.

“But the strips also provide a yield bump for the corn, because there are more outside rows.”

In fact, walking in the field, Rick Cruse, an Iowa State University field agronomist, said that the plants in many of the outside rows were producing two ears.

Fleishman usually drills 2 pounds of cover crop seeds per acre a few weeks before harvesting corn and soybean fields.

Due to the uncertainty of the weather patterns this season, he said he’ll try seeding from the air for the first time.

“I think it’ll turn out that drilling is better,” he said, “but sometimes nature just won’t allow it.”

Erosion notes

Cruse bluntly told farmers that if they follow acceptable erosion levels allowed by federal Natural Resources and Conservation Service guidelines, they will lose more soil than can be regenerated.

He said NRCS finds less than 5 tons of erosion per year is acceptable, however, a field can only regenerate about a half-ton of soil each year.

“And NRCS only measures sheet and rill erosion,” Cruse said. “But 35 to 40 percent of all erosion goes out by ephemeral gullies..”

Sheet erosion is the movement of soil across the surface plane of the field, mostly caused by raindrop splash and shallow flows of water across the surface. Wind can also cause sheet erosion.

Rill erosion occurs when runoff water forms small channels as it concentrates down a slope. They can be any size, but usually about 4 inches deep.

Ephemeral gullies are larger than a rill and usually results from the junction of rills. They appear on a cultivated field during planting and the growing season and erased by cultivation. After an ephemeral gully has been in existence for a few years, the area from which soil has been moved can be 100 feet wide or more.

Tillage moves soil into the ephemeral gully. This loose material is readily available for transport by runoff from the next rain, Cruse said.

He added that NRCS standards measure sheet and rill erosion, but have no calculation for ephemeral gullies.

So a grower can be in federal compliance as for sheet and rill erosion, but still lose additional soil through gullies, for which NRCS has no formula for determining the amount f soil loss.

According to NRCS estimates, as a state Iowa loses an average of 5.4 tons of soil per acre annually.

Cruse said ISU research has determined that cover crops can reduce erosion by 20 to 22 percent, but the best method is to take those areas of ephemeral gullies out of production and into grassed waterways.

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