There’s a new hybrid practice growers are taking advantage of that marries the benefits of cover crops with those of strip-till.
The practice of “bio strip-till” represents an advanced way of using cover crops to improve the crop-row environment, says Joel Gruver, a cover crop and soils agronomist at Western Illinois University in Macomb, Ill.
The concept is very new and is being defined mostly by cover-crop innovators. While more must be learned about yield impacts, advocates say bio strip-till improves soil health, reduces erosion, scavenges nutrients for the next crop and speeds up residue decomposition.
Bio Strip-Till’s Roots
Using radishes and other crops for bio strip-till started with cover-crop pioneer Steve Groff, the Holtwood, Pa., no-tiller who founded Cover Crop Solutions.
“I first started using this concept with Tillage Radish as a way to allow other cover crops to compete and establish,” Groff says. “I planted every other row with Tillage Radish, using a grain drill.”
Ironically, it was Lisa Stocking —a University of Maryland graduate student who later married Gruver — who gave him the idea.
Groff and Stocking blocked off holes in a no-till drill with 7½-inch spacings to place Tillage Radish on 30-inch rows. Then they planted into the strips of winterkilled radishes the following spring.
SEEDING INTO COVERS. Van Tilburg Farms in Celina, Ohio, has used this seeder and an air drill to seed cover crops. Then brothers Matt, Luke and Kyle Van Tilburg build strips into the cover crop later in the fall.
“I’m not sure who coined the phrase ‘bio strip-till,’ but it certainly fits the concept,” Groff says. “Later, when we started using precision planters — Ohio no-tiller David Brandt was the first farmer I know who did this — it was easy to fit bio strip-tilling with the planters used to no-till soybeans on 15-inch row soybeans.
“Tillage Radish was planted in every other row. Austrian winter peas were the most popular cover crop in the alternating rows, in between the rows of Tillage Radish.”
Other farmers who use planters with 30-inch row spacing fill half of the planter’s boxes with Tillage Radish, and the other half with Austrian winter peas or another cover crop, he says.
These farmers plant and then return, splitting the 30-inch row to create 15-inch row spacing. This works well with RTK guidance.
“Precision planting lets you to cut the cover-crop seeding rates in half, due to precise spacing of the seed vs. drills,” Groff says. “Going over a field twice with a planter that has 30-inch row spacing can be economical.
“Seed spacing with planters is generally 3 to 4 inches apart with most of the cover crops we’ve tried. We have the disc or plate-part numbers for most planters, so we can help farmers choose the right plate and settings for the different cover crops.”
Gruver says bio strip-tilling with radishes creates three distinct benefits:
1. Planting radishes on the same rows that will be planted to a subsequent crop may move some old crop residue away from the row, which can help no-tilling the following spring.
2. Radish growth may accelerate decomposition of other crop residue.
3. Since little radish residue remains aboveground, a burndown is easy if the tops don’t winterkill.
“Seeding radish as a cover crop tends to improve drainage and helps the soil warm up faster,” Gruver says. “Radishes winterkill and decompose very quickly. They leave a zone of nearly bare soil, but it’s soil with better aggregation and structural stability and it’s not likely to crust in the spring.”
IMPROVISING CONTROL. Wet weather prevented Indiana strip-tiller Gene Witte from killing annual ryegrass before planting corn, so he mowed and baled the cover crop and planted Roundup Ready corn. Witte planned on killing the annual ryegrass with glyphosate.
Two Bio Strip-Till Systems
Decatur, Ind., strip-tiller Gene Witte uses oilseed radish, annual ryegrass and clover seed to complement strip-tilling, crop rotations and manure application.
This year was his fourth planting corn into strips.
Witte first tried bio strip-tilling in mid-August 2009 after harvesting winter wheat and spreading liquid hog manure on the fields. He says strip-tilling fields spread with manure helps create a better seedbed and reduce soil compaction from liquid-manure tankers and dry-manure spreaders.
“The 2009 growing season was wet, and between the moisture and the hog manure, the radishes grew huge,” Witte says. “In the summer of 2010, the ground was bone dry when I seeded the radish and annual ryegrass, but everything sprouted and grew.
“I had a good stand of radishes and annual ryegrass, even though the radishes weren’t as big around as my finger.”
The radishes winterkilled in mid-December. Last spring, the annual ryegrass took off, aided by the hog manure. But the stand got out of hand because of wet weather plaguing the eastern Corn Belt. So Witte mowed and baled the annual ryegrass and sold the hay to a local cattle farmer.
“Having the cover crop get away from you in wet weather is one of the risks you take,” Witte says. “We got the annual ryegrass baling done on June 14 and planted the Roundup Ready corn June 16. The new growth of the annual ryegrass had just started as the corn emerged.”
Witte planned on waiting for more re-growth on the annual ryegrass before spraying it with glyphosate.
“This is what I like about the concept of strip-till and cover crops,” he says. “It gives you a little more window to control the cover crop without hurting the corn yields, because of the bare strip that strip-till creates.”
RTK Planting Works Well
Witte plants a mixture of annual ryegrass and oilseed radish on 15-inch rows using a Kinze 12-24 Interplant with splitter units.
“By strip-tilling, we get the benefits of annual ryegrass. We can easily plant into that tilled strip
It’s the same planter he uses for corn, soybeans and winter wheat.
Witte seeds a mixture of 15 pounds annual ryegrass and 2
pounds radish per acre. The seed comes pre-mixed in bags. He has a six-row Remlinger strip-till rig with 30-inch spacing, along with John Deere’s Green Star 2600 with an ITC receiver and RTK guidance.
Witte has talked to no-tillers who plant radish seed with a milo plate, but he thinks a soybean plate works better for the radish-annual ryegrass mix, which he describes as “a little more fluffy” than the hard radish seed.
Seeding Clover Covers
After harvesting winter wheat, Witte later frost-seeds a mixture of medium red clover and alsike clover. Then he strip-tills the field.
“I don’t kill the clover until the spring, when I apply a herbicide before planting corn,” Witte says. “With RTK, I can find the fall strips as I’m planting corn. By seeding the clover, I’m increasing the nitrogen in the soil, which the wheat crop had depleted.
“Years ago, when we had crop rotations longer than corn and soybeans, seeding clover was common.”
RADISH-WHEAT COMBO. Seeding radishes with wheat is a popular bio strip-till practice, says cover-crop pioneer Steve Groff. Some farmers seed radishes with winter wheat, while others seed radishes and Austrian winter peas after harvesting wheat in the summer.
Witte devotes about 15% of his acres to alfalfa, evenly splitting the balance between corn, soybeans and winter wheat. He contract-finishes about 1,500 hogs a year and gets half of the manure from the 2,500 hogs that a neighbor finishes. Witte also finishes about 150 Holstein dairy steers.
>“The fertilizer from the hogs and the cows add up to savings on the fertilizer for my corn,” Witte says. “I agreed to inject manure on my neighbor’s land in exchange for getting half of his hog manure for free.”
While some researchers and farmers have experimented with slurry-seeding cover crops in liquid manure, Witte says that won’t work with his row spacing and manure tanker.
“I prefer to plant the radish and the annual ryegrass on 15-inch row spacing, so slurry seeding with the 30-inch spacing of the knives on the manure tanker wouldn’t work for me,” he says.
Strip-Tilling Annual Ryegrass
At their farm in Celina, Ohio, brothers Matt, Luke and Kyle Van Tilburg are solid-seeding annual ryegrass in the fall and strip-tilling into the grass using a strip-till rig and Trimble RTK guidance.
In the fall of 2009 and 2010, the Van Tilburgs seeded annual ryegrass into soybeans using a high-boy seeder with drop tubes. They returned with a 60-foot-wide Wil-Rich toolbar with 24 Soil Warrior units mounted on 30-inch spacings.
The Soil Warrior coulters kill the annual ryegrass growing in the strips. For corn following soybeans, the Van Tilburgs don’t apply phosphate or potash because these nutrients are in the poultry manure applied to the fields.
For corn-on-corn, they apply ammonium sulfate. In the spring, the brothers make another shallow pass with the strip-till rig, then they plant corn.
RADISH-ANNUAL RYEGRASS. Indiana bio strip-tiller Gene Witte uses a mixture of radishes and annual ryegrass, which he seeds into winter wheat stubble and then fall strip-tills. The radishes winterkill and Witte typically uses herbicide to kill the annual ryegrass before planting corn.
Before the Van Tilburgs began strip-tilling after seeding annual ryegrass, the ryegrass roots created problems for planting corn, even after the cover crop was sprayed with herbicide.
“The roots were so thick and tough that we couldn’t get the furrow ‘V’ to close,” Van Tilburg says. “By strip-tilling, we get the benefits of annual ryegrass. We can plant into that tilled strip in the spring and control traffic.
“For us, this is the best of both worlds: cover crops and no-till. You have to have something growing on your soil year-round to help it.”
Cover Crops Build Soil
Over the years, the brothers have flown on annual ryegrass with an airplane and seeded it with an air drill, followed by shallow vertical tillage to incorporate the seed. To make seeding easier, they are building a custom cover-crop seeder with a 90-foot-wide boom and drop tubes.
“It’s in our shop, but this high-boy seeder will be ready this fall,” Van Tilburg says. “It will be a dedicated cover-crop seeder that will be able to seed into standing soybeans, standing corn or any crop.”
Van Tilburg says it’s hard to quantify how much cover crops improve yields in bio strip-till, although their best corn yield from the dry 2010 growing season occurred in fields seeded with annual ryegrass that were strip-tilled. The benefits accrue over time.
“For years, farmers have tested their soil, looking at phosphorus and potassium, to build the soil chemically,” Van Tilburg says. “But we haven’t done a good job of building the soil’s organic matter and tilth. There’s definitely a benefit to that.
“The tap root of the clover opens up the heavy clay subsoil to allow channels for improved soil aeration and water filtration...” — Blake Vince
“When I drive by a fenceline that has never been tilled, the soil is 6 to 8 inches taller than the rest of the field. That reminds me what we have to start doing to build our soils.”
Strip-Tilling With Clover
While radishes and annual ryegrass get lots of attention in bio strip-till, Blake Vince of Merlin, Ontario, relies exclusively on red clover. He grows corn, soybeans and wheat in the province’s southwest region.
Vince’s bio strip-till system starts with frost-seeding red clover onto dormant winter wheat in March or April once the snow disappears and the fields are fit.
Vince applies 8 to 10 pounds of clover seed per acre with a spinner spreader mounted on an ATV.
The freeze-thaw cycles in the spring help work the small clover seed into the soil.
The clover grows up in the field after the wheat is harvested in July. Then, in mid-August, Vince chops the clover with a Bush Hog rotary cutter to reduce weed competition and stimulate root growth.
“I don’t touch the field again until October, when I apply dicamba and glyphosate to kill the clover,” Vince says. “If clover is left to overwinter, it can be quite a challenge to kill in the spring.”
Tips For Bio Strip-Tilling Radishes And Peas
Ten days after applying herbicide, Vince starts to make fall zones with an eight-row ETS Soil Warrior on 30-inch-spacings that’s equipped with Trimble RTK guidance.
With the dual-compartment tank on the Soil Warrior, Vince applies a blend of 120 pounds MAP and 120 pound of potash per acre. He plants corn with a conventional 16-row, 30-inch John Deere 7000 planter without coulters.
He recently added a new attachment called a “row basket” in front of each row unit to firm the soil and move residue.
Vince says crop yields are improving. In 2010, corn yields were 178 to 200 bushels per acre. Wheat yields were 93 to 115 bushels per acre, while soybeans hovered around 50 bushels per acre.
“The limiting factor to high yields is our soil type,” he says. “The topsoil in our geography has 3 to 5 inches of Brookston clay with heavy clay subsoil, which is classified as imperfectly drained. Tile drainage is paramount to achieving top yield.”
The clover in Vince’s bio strip-till contributes 50 to 100 pounds of nitrogen per acre, according to research from the Ontario Ministry of Agriculture. But the clover does more than add nitrogen.
“The tap root of the clover reaches deep into the soil profile to help recycle nutrients to the top,” Vince says. “The tap root helps open up the heavy clay subsoil to allow channels for improved soil aeration and water filtration.
BETTER SEEDBED. Strip-tilling in the fall into an annual ryegrass creates a better seedbed for corn in the spring, says Celina, Ohio, bio strip-tiller Matt Van Tilburg.
“I have witnessed clover roots — identified by nodules — growing in tile drains 36 inches below the surface of the ground.”
RTK Helps Bio Strip-Till
As more strip-tillers use cover crops, RTK guidance systems allow them to experiment with new uses, Gruver says.
“You can plant right over the row where the cover crops were planted the previous year,” he says. “Everyone I’m aware of who bio strip-tills uses radish, although I think they could use other crops, too.
“But the rapid fall growth and winterkill of radishes are optimal for what bio strip-tillers are trying to do.”
Relying on RTK, Witte plants corn between the 15-inch-wide rows of radish and annual ryegrass planted the previous summer.
“When I strip-till in the fall, I go down between the 15-inch rows in the soybean fields. In the spring, I plant corn between the rows where the radishes and annual ryegrass grew,” he says. “The corn roots go down into the soil where the radishes and annual ryegrass had been. By planting between the rows of cover crops, the corn establishes better.”