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Farming trifecta: No-till, cover crops, and a diverse rotation

Brian Johnson eyes wheat stubble dotted by a bountiful cover crop of tillage radishes on his family’s north-eastern South Dakota farm. 

“This is the new tillage,” says the Frankfort, South Dakota, farmer, who farms with his wife, Jamie, and his father, Alan. Cover crops like tillage radishes can shatter compacted soil layers on no-till fields like the ones farmed by the Johnsons. 

Cover crops, though, are just one component of the Johnsons’ strategy. They’ve also teamed them with no-till and a diverse crop rotation to help mimic the native prairie. 

Before European settlers broke them, native prairie soils had up to 9% organic matter, says Jeff Hemenway, an NRCS soil scientist based in Huron, South Dakota. Most soils now have one half or less of that amount. Organic matter helps boost soil water holding capacity, aids nutrient uptake, and helps curb soil erosion. 

The good news is, tools like no-till, cover crops, and diverse rotations can build organic matter. It takes time, as just a 1% rise can take 20 years. Along the way, though, you can glean other benefits. Here’s how.

start with no-till

The Johnsons’ roots in no-till started way back in 1986, when Alan switched to no-till. At that time, a large challenge was clearing residue for the seed and seed furrow. 

“We had to find the right openers on the planter to plant in a timely fashion,” says Brian. “With the equipment we have today, we can do it.” 

A key was equipping their planter with Yetter SharkTooth wheels. “They are critical for planting through high-residue environments,” says Brian. 

No-till also requires fertilizer application adjustments. “Placing nitrogen fertilizer in proximity to the row is a must,” says Dwayne Beck, who manages the Dakota Lakes Research Farm near Pierre, South Dakota.  He adds that popup starter fertilizer containing phosphorus is also a normal practice under no-till. 

Diversify Rotations

Building healthy soils also means diversifying rotations. Fifty years ago, spring wheat was the “it” crop in northeastern South Dakota. These days, the region mirrors a mini Iowa, with corn and soybean fields dotting the landscape. 

Part of the reason is the prolific precipitation that the area started receiving in the 1990s and into most of the 2000s. “It was frustrating because, for about 10 years, we could not plant spring wheat,” says Brian. 

In recent years, though, the weather has dried out enough that spring wheat can once again diversify their corn and soybean lineup.  

“With a corn and soybean rotation, you end up getting a platy soil structure,” says Hemenway. “That makes it tough for roots to penetrate.”

Diversifying the rotation with spring wheat (as the Johnsons have done) can alter soil aggregates that encourage roots to more easily branch out. 

Wheat can also spark more profits when inserted into a row-crop rotation. Data from a 2013 Dakota Lakes Research Farm rotational study showed the impact that rotational diversity has on corn yields. 

Continuous Corn: 203 bushels per acre 

Corn-Soybean: 217 bushels per acre 

Corn-Corn-Soybean-Wheat-Soybean: 235 bushels per acre 

Producing wheat costs less than does corn and soybeans. Diverse rotations also help reduce  disease potential and weed and insect resistance in those crops.  

“Basically, the production costs for these are 50% of what a corn and soybean rotation would be,” says Beck. “So essentially, they can grow wheat for free.”

Wheat’s benefits aren’t just limited to the Great Plains. A 12-year University of Illinois (U of I) study found that adding wheat to a corn-soybean rotation boosted corn yields by about 10 bushels per acre and soybean yields by 3 to 5 bushels per acre, says Emerson Nafziger, a U of I Extension agronomist. 

Entry Way for cover crops

Wheat also helped the Johnsons pave a way to plant cover crops. 

“With the precipitation we’ve had, we started having some saline and compaction issues with no-till,” says Brian. To help curb the effects from these stressors, they began planting tillage radishes into wheat stubble following harvest. Any surviving radishes and volunteer wheat are terminated the following spring prior to planting the field to corn or soybeans. 

“We want to keep something growing,” says Brian. “Every year, we get a little better at it.” 

Cover crops do require an investment, as seed costs for them normally hover around $16 per acre, says Brian. He believes, though, that it helps stimulate soil microbes that help increase soil fertility and soil health. 

Keeping soil covered also helps slice soil erosion potential. Another way the Johnsons protect the soil is by planting corn and soybeans in 20-inch rows. 

“It covers the ground better than wider rows,” says Brian. 

It’s also a way to boost soybean yields. It’s backed by U of I research that showed, on average, narrow-row soybeans outyield those in 30-inch rows by 2 bushels per acre.

There’s an if, though. Yields for narrow-row soybeans may be less if the field has a white mold history, say U of I agronomists. 

Video: Johnson outlines how radishes in 2015 as a cover crop helped spur 2016 crop production.

long-term benefits

In the short-term, steps like no-till, diverse rotations, and cover crops may not immediately boost yields. They can set the stage for improved soil health that bodes well for future yields and long-term soil health.

It’s also a way for farmers to return to a time when they included perennials like pasture or alfalfa for a few years before returning the land to small grains or row crops, says Beck. 

Perennial plants have likely come the closest to emulating native prairie. “Perennials can root down as deep as 9 feet, which can suck out the excess water and nutrients in the soil profile,” says Beck. 

Rotation deters corn rootworm

Corn-on-corn and corn rotated with soybeans are king in the Corn Belt. Farmers aren’t the only ones who love them. Insects also love tight rotations like corn and soybeans, says Dwayne Beck, who manages the Dakota Lakes Research Farm near Pierre, South Dakota. 

In some areas like east-central Illinois, the western corn rootworm variant has thwarted the corn-soybean rotation by laying eggs in adjacent soybean fields. When farmers plant corn on that soybean ground the following year, rootworm eggs hatch and infest the corn. 

Meanwhile, extended diapause in some areas prompts eggs to delay hatching until two years after they are laid. That’s just in time for rootworm larvae to feast on corn that’s planted after an interim soybean year. 

That’s why including a small grain like wheat into a corn and soybean rotation can help manage corn rootworm, says Beck.

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