A few years ago, many strip-tillers in the Corn Belt struggled to harvest crops in wet fields, which limited or even eliminated fall strip-tilling.
More recently, it's fields with dry soils that could pose problems for strip-tillers. But following three strategies can help strip-tillers manage dry soils, says Jodi DeJong-Hughes, University of Minnesota Extension crops and tillage educator.
“Farmers who have been strip-tilling for 5 years or more will likely have fields that are more mellow and have better soil aggregation,” DeJong-Hughes says. “But those who have been strip-tilling less than 5 years are more likely to have fields with dense, compacted soils.
“When strip-tilling, dry and compacted soil can break up into chunks, which can cause seedbed problems next spring ranging from uneven seed-depth placement to erratic emergence and stands.”
Using Vertical Tillage
First off, DeJong-Hughes says, a strip-till rig with shanks or moleknives will dig into dry soil, while some strip-till rigs with coulters may not be able to penetrate the hard soil. But shanks and moleknives can tend to bring up chunks of soil, too.
“Without additional weight and/or down pressure, some strip-till rigs with coulters might bounce along on the top of dry soil …”
“Without additional weight and/or down pressure, some strip-till rigs with coulters might bounce along on the top of dry soil,” she says.
Secondly, more strip-tillers who grow corn-on-corn — which is become attractive with current corn prices — are using a vertical tillage tool after harvesting corn and before strip-tilling in the fall, DeJong-Hughes says.
"They’re sizing the corn stalks, which improves residue flow when they strip-till, and they’re incorporating the residue just a little — usually 1 inch deep,” she says. “Running a vertical-tillage tool an inch deep before strip-tilling can crack the soil and reduce problems with soil breaking up into chunks.”
It’s possible that freezing and thawing during the winter will break up chunks from fall strip-till, if the weather cooperates, De Jong-Hughes says. If another mild winter leaves chunks in fall strip-tilled fields next spring, strip-tillers can run vertical-tillage tools over that ground.
More and more strip-tillers are using vertical-tillage tools in this way, she says. That includes one strip-tiller she knows who’s growing continuous corn on 22-inch rows.
“He wanted to know what strip-till rigs would work with 74% residue,” DeJong-Hughes says. “There aren’t many strip-till rigs set up for 22-inch spacing on the staggered rows needed for residue flow. By running a Salford RTS over the field before strip-tilling in the fall, this strip-tiller reduced the residue level to 54%.”
However, there may be a downside to vertical tillage, DeJong-Hughes says. Using a these implements over fields every year may reduce soil aggregation and water infiltration — even if the tool is run only 1 inch deep, she says.
As a precaution, strip-tillers may want to use vertical tillage only just in field areas where residue really builds up.
The third strategy for strip-tilling in dry soils involves banding anhydrous ammonia.
“Sealing and covering the soil when strip-tilling with anhydrous ammonia is extremely important,” DeJong-Hughes says. “There’s less volatilization in dry year if anhydrous is placed deep enough and the soil seals. One of the advantages of strip-tilling in a dry fall is that the residue protects soil moisture. And there’s not a lot of moisture out there right now.”
The depth of fertilizer placement in strip-till affected yields for at least one Minnesota strip-tiller DeJong-Hughes has worked with. The grower compared banding about 160 pounds of anhydrous ammonia at 5½ and 7½ inches when he strip-tilled in the fall of 2011.
Corn yields on ground with anhydrous banded at 7½ inches were better than the shallower-banded anhydrous, she says. The farmer also applied 5 to 6 gallons per acre of 10-34-0 as starter when planting corn last spring.