Michigan farmers say larger root mass helps increase corn yields by 30% in spring strip-tilled fields.

Ask Floyd Koerner III why he and his father, Floyd Koerner Jr., switched to strip-till after 25 years of continuously no-tilling corn and soybeans, and the Laingsburg, Mich., farmer gets right to the point.

"Fertilizer efficiency was the biggest reason," says Floyd Koerner III. "Placing it right below the plant uses considerably less fertilizer.

"We've saved 40% on our fertilizer cost by banding instead of broadcasting it. That's in line with what other strip-tillers are saying about their fertilizer savings."

Spring Stripping

There are three main reasons why the Koerners strip-till all of their corn and soybean fields in the spring. First, snow and ice can come early in the fall in central Michigan. Second, the water-quality program they participate in bans fall application of nitrogen. And third, they use cover crops.

"We farm hilly ground and we have concerns about fall erosion," the son says. "Our ground is not always set for fall strip-till and we have cover crops and you can't fall strip-till with cover crops.

During the past 7 years, the Koerners have learned several lessons about effectively strip-tilling in the spring.

1. Don't strip-till ground that is too wet.

"If you go out on fields too early, then you will have problems. You don't want to bring up wet ribbons of soil that will dry out in clods, which you cannot plant into," Floyd Koerner III says. "I can see where strip-till would not work on heavy clay until it is dry enough to work.

"You have to wait when spring strip-tilling. Wait until it is dry enough to no-till before you start strip-tilling."

2. Patience pays.

"After strip-tilling, I like to wait a day to let the soil warm up before planting," the younger Koerner says.

He strip-tills and his father plants the corn and soybeans the next day. When the Koerners strip-till, they put down High NRG-N and Sure-K, which are liquid nitrogen and potassium products, respectively.

"You need to dry and warm up the soil before you plant it," Floyd Koerner III says. "Some people are worried that if you wait a day after strip-tilling, the ground will dry out too much. That's not so.

"Let the soil warm up and aerate and dry a bit before you seed. That has increased our final stand immensely."

3. Use narrower "summer" points on the shanks.

"We use a narrower point in the spring to disturb less soil," Floyd Koerner III says. "The tooth on the end of the shank is narrower. Blu-Jet's manufacturer calls them summer and fall points.

"I use the summer points, which are narrower, to strip-till in the spring. Wider points make too high and wide of a berm. They also disturb too much residue."

Equipment Setups

The Koerners have used a Blu-Jet SubTiller III for about 6 years.

"We added Blu-Jet hiller discs, rolling baskets and an 800-gallon fertilizer tank," Floyd Koerner III says. "We also welded on half-inch, stainless-steel tubing to inject liquid fertilizer.

"I've played around with the depth of the strip-tiller and the fertilizer placement. We now strip-till at a depth of 10 inches and we place fertilizer 6 inches deep."

The Koerners use an eight-row White 6700 planter with 30-inch row spacing, which is set up for no-tilling corn and soybeans. The planter is hooked up to a Blu-Jet LandTracker that has an 800-gallon tank for High NRG-N, which they apply for corn at about 10 gallons per acre through injection coulters on the LandTracker.

It also carries a 150-gallon tank for applying Pro-Germinator, a phosphorus product that goes on at about 4 to 8 gallons per acre. Pro-Germinator is applied through Schaffert Rebounders with "Y" splitters.

The Koerners run the row cleaners shallow to remove any residue or clods in the strips. The planter has Accu-Plant double-disc and Tru-Vee openers. They added Schlagel Posi-Close closing wheels.

"We were tired of rebuilding the original closing wheels," Floyd Koerner Jr. says, adding that the rubber kept coming off the wheels.

Increased Corn Yields

While the Koerners switched from 35 years of 100% no-tilling their corn and soybeans to spring strip-till to save money on fertilizer costs, they love what strip-till has done to their corn yields.

"Unbelievable," Floyd Koerner III says. "Our corn yields are 30% better. Our 7-year average for strip-tilled corn was over 165 bushels per acre.

"Our 7-year average for no-till was 120 bushels per acre. We are getting a lot deeper root mass with strip-till."

When the Koerners no-tilled, they seeded about 170,000 soybeans and 27,900 kernels of corn per acre and had final stands of 120,000 to 145,000 in soybeans and 23,000 to 24,000 in corn. As strip-tillers, they plant 120,000 soybeans and 30,000 kernels of corn per acre.

"In strip-till corn, a lot of fields will have final stands of 29,700 to 29,800," Floyd Koerner III says.

Seven years after switching to strip-till, the Koerners remain amazed at the difference it has made for their corn yields.

"The big thing we've seen is an increase in the amount of corn roots with strip-tilling," Floyd Koerner III says. "It takes roots to get yield and strip-till makes ideal conditions for roots. You need to get those roots down to water and nutrients.

"Compared to no-till, the corn roots are going down farther in strip-till. After you strip-till, there is less soil compaction in the growing zone. In our continuous no-till fields, our corn roots were stopping about 6 inches down," he says.

"No-tilled corn roots won't go as deep," his father adds.

"The big thing we've seen is an increase in the amount of corn roots with strip-tilling. It takes roots to get yield and strip-till makes ideal conditions for roots. You need to get those roots down to water and nutrients." 

- Floyd Koerner III,
Laingsburg, Mich. strip-tiller

Corn planted into the strips benefits from soil, which warms up faster than it does in no-till, Floyd Koerner III says.

"When you disturb the soil, water moves up to where you disturbed it. No-till pulls cold soil moisture to the surface, where the seed has been placed," he says. "Where I strip-till, there is a noticeable temperature difference between the strip and the middle of the rows, where the residue is. The strip-tilled soil is warmer."

The Koerners have not seen as big of a difference in soybean yields since switching to strip-till as they did in corn.

"We are getting all of the soybean plants to grow because the roots are going down farther than they were in no-till," Floyd Koerner III says. "That's a benefit to strip-tilling them. But we haven't seen a big increase in yield in strip-tilled soybeans like we have seen in strip-tilled corn."

Growing conditions in Michigan during the past 5 years have been tough, which is reflected in state yields, he says.

"I save on soybean seed costs and we are getting a few bushels more per acre," Floyd Koerner III says. "Strip-tilling soybeans is not costing me money."

Cover Crops

While Floyd Koerner III likes the increased yields and the fertilizer savings with strip-till, he remains committed to no-till.

"My goal is to get back to no-till if I can get the yields even with strip-till," he says, adding that cover crops can play an important role in this.

"With cover crops, the roots go down into the soil and then they decay, leaving channels for the roots of your corn and soybean crops and for the rainwater to follow. These effects of the cover crops would provide some of the same benefits that we get with strip-till," Floyd Koerner III says.

The Koerners have been using cover crops for the last 4 years, mainly annual ryegrass aerially applied on September 1 in their corn and soybeans. This year, they started using some cereal rye seeded with their no-till drill in both corn and bean ground.

"We can get a heck of a good stand with a lot less seed with the no-till drill," Floyd Koerner Jr. says.

The Koerners now split their cover crops between annual ryegrass and cereal rye, and are considering trying some radish this year.

"Your rye cover crop suppresses a lot of your winter annuals," Floyd Koerner III says. "We kill our cover crop in April. The exact time depends on the spring.

"I'd like to kill it April 1, but last year it was the end of April."