Improving Seed-To-Soil Contact In Fall Strips
By Dan Zinkand
Just because strip-tillers got fields stripped in the fall doesn’t necessarily mean everything is fine now, says Kevin Kimberley, owner of Kimberley Ag Consulting, Maxwell, Iowa.
“In traveling throughout Iowa, Illinois, Nebraska, the Dakotas and Minnesota last fall and this winter, I’ve seen strip-tilled fields where there are lots of chunks of dirt,” Kimberley says. “If there aren’t good rains this spring to soften those chunks and let the soil settle into the strip, farmers can encounter a variety of problems when they plant.”
Two of the biggest problems are down pressure and poor seed-to-soil contact, which leads to many more problems that can cut corn yields by 20 to 40 bushels per acre or more, Kimberley says.
If strip-tillers aren’t using three coulters per row on their strip-till toolbar, there may not be enough down pressure when they plant corn, he says. When strip-tilling with a single coulter and a knife on each row, the normal width of the strips is 6 to 8 inches.
“In these strips, where your planter has normal-width gauge wheels that are about 14 inches wide, some of the wheel will be in the loose soil in the strip and some of the wheel will be riding on hard ground,” Kimberley says. “As a result, they aren’t riding evenly, which affects depth of placement and seed-to-soil contact.”
This seed-to-soil contact problem can also occur where the gauge wheels are running on hard ground on either side of the strips, Kimberley says.
“When the gauge wheels run on hard ground, you can’t form a true ‘V’ correctly or the true ‘V’ may not be tight enough in the ground,” he says. “If the true ‘V’ isn’t tight enough, then the soil can dry out more quickly, which can make seedlings struggle when they germinate.”
He adds that if the planter can’t make a proper true ‘V’, the sidewalls can fall into the furrow, which interferes with good seed-to-soil contact and may delay emergence.
Fields with chunks of dirt in the strips were either worked too wet last fall or were very dry and compacted, Kimberley says. But there are a number of options strip-tillers have if Mother Nature’s timely soaking rains don’t bail them out.
First, consider running through last fall’s strips with a strip-till rig set up with a ripple coulter and a narrow knife that’s about 3/8 of an inch thick. Run the knife 4 to 5 inches deep and the coulter 1 inch deeper, Kimberley says. But be willing to adjust the depth, based on soil conditions.
Second, running over strips with a strip-till rig can help strips in wet fields dry out more quickly, Kimberley says.
“In the spring, some strip-tillers look at wet fields with clods in the strips and want to run 8 or 9 inches deep,” he says. “But running that deep — especially in very wet, mucky ground — would just make that ‘chunky, blow-out problem’ even worse,” he says. “Instead of going deeper, you want to shallow up the knife and/or coulter depth so the soil flows. This may be about 4 to 5 inches deep. Base the depth that you run on the soil conditions, because there’s no one-size-fits-all magical advice.”
By aerating the soil, it will warm up faster, allowing the field to be planted faster. For example, he worked with a farmer with several thousand acres of corn. Kimberley advised him to go in and till the strips on about 1,000 acres. When these fields were done, the rest of the corn ground was also ready to plant, too.
Third, some strip-tillers who have fields with clods of dirt over the strips decide to go into their fields with a vertical-tillage tool, like a Case IH 330, Kimberley says. Running such a tool in these situations can break up the clods and fill in the air pockets in the strips, which will improve seed-to-soil contact.
If strip-tillers have lots of clods over the strips, they also have air pockets in those strips, Kimberley says.
“If you try to plant into strips with clods and air pockets, the seed may end up at an uneven depth and also may not have enough contact with the soil,” he explains. “If there’s not good seed-to-soil contact, germination can slow or the seed may not even have enough moisture to germinate. When this happens, emergence is uneven and so are stands, all of which can reduce yields.”
Kimberley believes seed-to-soil contact problems are greatly overlooked, mostly because strip-tillers are relying on monitors to do all of their thinking.
“For example, they think that it’s enough to know what the down-pressure reading is on the monitor. We need to go back to the fundamentals," he says. "Get out of the cab and check the sidewalls for compaction. And check for good seed-to-soil contact, too. Check to see if the spacing and the depth is what you think it should be.”
Small problems ignored over time can create systemic failures, Kimberley says. In 2011, one of Kimberley’s clients attended a winter meeting that Pro Farmer had in Chicago where a NASA scientist talked about the problems that led up to the explosion of the Challenger space shuttle in 1986.
According to the customer, here’s what a NASA engineer explained.
“If you keep deviating from what is normal, over and over again, it quickly becomes ‘normal’ and that is dangerous,” the NASA scientist said. “If you take shortcuts long enough, you will be caught short.”
Kimberley says the same thing happens in agriculture, even with good farmers using RTK, monitors and all of the other latest precision technology.
“If you keep getting by with what you’re doing, it becomes normal to you,” he says. “Eventually, you will get caught when Mother Nature fails to bail you out.”
One of the major deviations at planting is poor seed-to-soil contact, Kimberley says.
Years ago, it seemed that farmers in the Corn Belt, for example, could count on timely rains during the summer months, Kimberley says. But betting on Mother Nature to ‘catch up’ corn crops with uneven emergence and other problems is no longer a sure thing.
“We get bigger rains these days,” he says. “We get 4- and 5-inch rains, even in July and August. Back in the 1970s and ’80s, we used to pray for rain,” Kimberley says.
Farmers who count on the weather to bail out fields with uneven emergence are living in the world of the normalization of deviation.
“When corn plants emerge evenly, they can set ears with greater girth and length, which means more yield than in uneven stands,” Kimberley says. “In uneven stands, the late-emerging corn plants will be shaded out and not receive enough sunlight. Then the corn in the field may pollinate at different times.”
These late-emerging plants also act like weeds, which compete for water and nutrients in the soil with plants that emerged earlier.
“The ears on these late-emerging corn plants don’t produce the yield you were counting on,” Kimberley says. “The test weight on these runt ears is light and the moisture is high.”
The upshot of all these problems is that late-emerging plants set ears with smaller girths and shorter lengths and that costs you yield at harvest, Kimberley says. If it’s only 5 or 10 bushels per acre, a strip-tiller has lost $25 or $50 per acre with $5 corn. But if it’s 20 or 40 bushels, that’s $100 or $200 per acre.
“Year after year, I keep seeing fields where the losses from uneven emergence are in the range of 20 to 40 bushels per acre,” Kimberley says. “You get only one chance a year to plant your crops right and on time, so you need to do it right the first time.”