These two strip-tillers have increased — not decreased — their yields, and heavy residue hasn’t been a problem.
Are you considering continuous no-till corn? Do your homework and you’ll find plenty of reasons to doubt this option, but also some strong arguments that support the logic for more corn-on-corn.
The first mental hurdle is yield. Crop rotations have consistently beaten corn-on-corn in the combine.
RESIDUE OVERCOME. Heavy residue from corn-on-corn doesn’t prevent strip-tilling. Seth Spicer and Mark Schroeder both use Redball units similar to this one to create clean berms.
When Purdue University researchers reviewed all the known published data comparing continuous corn to corn/soybean rotations, rotated corn yields won by 5% to 15% in all but two of the studies. And it should be pointed out that yield reductions in continuous corn were usually much greater in stress years.
“Over the past decade, all of my research shows that corn following corn has yielded about 10% less than corn following soybeans,” says University of Illinois crop scientist Emerson Nafziger. But, he adds, the studies haven’t slowed down growers who say they make more money from corn-on-corn than a rotation, even with the yield hit.
There are sound agronomic arguments for corn-on-corn, too. Higher residue production can cause headaches for continuous corn growers, especially no-tillers, but it can also accelerate organic matter production. A corn/soybean rotation can actually cause organic matter to decline. Boosting organic matter improves soil structure, water-holding capacity and microbial activity, among other good things.
More bottom-line news: studies show overall corn yields increasing faster than soybeans. For statistics buffs, U.S. corn yields have inched upward 1.3% (1.8 bushels per acre per year), while soybean yields have gained only 1% (about 0.4 bushels per acre) since the 1960s.
Meanwhile, soybeans have recently been hit with more pest problems, including aphids, sudden death syndrome and the yet unknown impact of soybean rust. Rotations are also showing less detrimental effect on corn rootworms.
For these and other reasons, trend lines indicate a gradual increase in continuous corn.
Strip-tilling, which combines the soil drying and warming benefits of conventional tillage with the soil-protecting advantages of no-till, ranks high among the ways growers are contending with the challenges of continuous corn.
Seth Spicer, Imperial, Neb., and Mark Schroeder of DeForest, Wis., while dealing with different weather patterns, soil types and cropping strategies, have both found that strip-tilling and zone management pay off with warmer, mellower seedbeds, earlier emergence, uniform stands and higher yields.
Spicer has been growing 1,100 acres of continuous corn for 4 years under center-pivot irrigation on sandy soils. Corn yields, which have increased each year with Spicer’s no-till/strip-till cropping system, now average between 210 and 220 bushels per acre.
He strip-tills and bands fertilizer during the spring a couple of weeks prior to planting. “With our soil types, we would risk losing the fertilizer over the winter if we strip-tilled and applied fertilizer in the fall,” he explains.
Improved water infiltration with strip-tillage is critical in Spicer’s water-short region, where a declining aquifer has led to restricting irrigation pumping to 13 ½ inches per year. “The mellow soil in the strip-tilled fields really makes a difference. With conventional tilling, water from the center pivot was likely to run off. Now it soaks right in,” he says.
In past years, Spicer used a one-pass system with a planter mounted on an Orthman 6-row strip-till unit. Last fall he switched to a Redball 12-row strip-till machine, and at the same time he installed a Trimble AutoPilot guidance system on the tractor.
“With the one-pass system, I found that in a wet spring, soil was often too cold for good emergence,” Spicer explains. “With the new system, I start strip-tilling in mid-March and let the soil warm up for a couple weeks before planting. I got the cleanest strips this spring that I’ve ever had.”
He uses a 12-row John Deere 1710 MaxEmerge with standard row openers. Spicer estimates that soil in the strip-till berm is usually about 10 degrees warmer than the average soil temperature in a no-tilled field.
Automated steering was a timely and economical decision. “By adding AutoPilot, I didn’t have to buy markers for the strip-till rig. That saved me almost a third of the cost of the steering system,” he says.
The precision steering system started paying off immediately. “With automated steering, you can pay less attention to what’s ahead of the tractor and focus more on the planter. Making sure everything is working with a 12-row system while staying on the strip-till slot is a lot to watch,” Spicer explains.
“Seed-to-soil contact is a primary issue with strip-tilling,” he adds. “You must be sure all the trash is removed from the row, and if you get a little lax and drive a bit crooked, you’re in trouble. If your openers are set for clearing the slightly raised strip-till berm, when they go off the strip they no longer remove trash and you end up with seed on top of the ground or a lot of hairpinning of residue.”
Less Nitrogen Needed
Soil is strip-tilled to a depth of 9 to 10 inches while 20 gallons of a mixed fertilizer is simultaneously applied. At planting, Spicer applies a starter mix 2 inches to the side of the row and 3 inches deep, then finishes feeding the corn crop through center-pivot sprinklers. Fertility needs are based on 220-bushel-per-acre projections.
“I didn’t see any yield drag when we shifted into no-till/strip-till. In fact, we’re getting better nitrogen utilization with strip-till and higher yields with less total nitrogen. With conventional tillage, we didn’t have the nutrient concentration in the root zone. I’m now growing a bushel of corn with 0.7 to 1 pound of nitrogen,” he says, and yields have increased about 20 bushels per acre during the 4 years of strip-tilling.
Residue Not A Problem
Increased corn residue has not hampered Spicer’s continuous corn fields, thanks to a winter grazing program. He also runs a stalk chopper when needed to encourage breakdown.
Genetic seed technology has greatly reduced potential insect problems, but Spicer keeps a close eye on disease threats. He doesn’t have rootworm problems, and he holds off corn borers and western bean cutworms with hybrids containing the Herculex insect protection trait.
“I heard reports from field scouts last year of Goss’ Wilt in some area fields. It’s something we’ll have to watch for. Hybrid selection is the best protection,” he says.
Goss’ Wilt, usually a late-season disease, infests crop residue and spreads to growing plants.
Mark Schroeder says a combination no-till and zone banding system was exactly the right move for the 3,000-acre cash grain operation he manages with his father, Ken, north of Madison, Wis. Corn yields have increased from between 140 and 150 to more than 160 bushels per acre since they switched from conventional tillage in 1993.
The Schroeders follow a 4-year rotation, growing 2 years of corn-on-corn, followed by wheat and soybeans. “We’re not yet long-term continuous corn growers, but we think we have the right system should we decide to go that route in the future. Our decision on cropping strategy will depend on what the market dictates,” he says.
Schroeder says wheat is a profitable crop, if managed properly. They no-till wheat into soybean stubble in the fall on a couple of hundred acres and have good local markets for both the harvested grain and straw. “Wheat spreads cut the workload and diversifies the operation. It helps build organic matter and is beneficial to the no-till process,” he explains.
They first tested zone banding with a Rawson coulter cart during a wet spring in 1993, and based on the results, they went full-acreage with the system in 1994. They have owned three coulter carts, and a couple of years ago they converted an 8-row into a 16-row unit.
“In past years, we applied dry fertilizer with the coulter cart in the fall and then ran the cart over the zone again prior to planting. It might be a day before, a half a day or as little as 2 hours before planting, depending on conditions. But we think this second tillage pass is absolutely essential to creating a good environment for better seed-to-soil contact,” Schroeder explains.
Last year they tried an 8-row Redball strip-till machine for a day, and they ended up tilling a strip 6 to 8 inches deep on 90 % of their second-year corn acres following harvest.
“It’s a good tool for working the soil in the fall. It loosens the seedbed, creates good soil tilth and does a really good job of dispersing residue,” Schroeder says.
Except for some areas that dried out and warmed up in time for planting, they also ran the coulter cart over the strips before planting last spring. “We ended up with a tremendous seedbed,” he adds.
Their primary planting unit is a 16-row, 30-inch John Deere 1770, modified with Dawn heavy-duty row cleaners, Keeton seed firmers, Martin spading closing wheels and drag chains. Liquid starter is applied through the seed firmer tubes and about half of the crop nitrogen is applied in a 2 by 3 inch pattern with the planter. The remainder of the nitrogen is sidedressed.
They plan to apply dry phosphorus and dry potassium fertilizer 6 to 7 inches deep when they strip-till with the new rig this fall. Schroeder says the banded fertilizer placement will be much more uniform and available than what they got with the coulter cart. “The cart more or less blows the fertilizer on the surface and the coulters work it in only 3 or 4 inches,” he explains.
The no-tillers have experimented with fertilizer applications for several years.
“Based on test plots, we’re beginning to think we can apply a lot more of the nitrogen with the planter without affecting production. We’re currently testing two-thirds at planting and one-third sidedressed to determine the best ratio. If we could cut out the sidedress application completely without hurting yields, it would save a lot of labor and high-priced fuel,” Schroeder says.
“We surely don’t want to hurt our harvests, but it also looks like we can consider some fairly sharp reductions in nitrogen rates overall,” he adds. “Tests indicate we can get by with one-half to seven-tenths pound of nitrogen to grow a bushel of corn.”
Last year, yields from strip tests getting 80 units of nitrogen yielded equally – 215 bushels per acre – to areas of the same filed where 200 units were applied.
Schroeder thinks there is at least some correlation between doing a good job of strip-tilling and the improved nitrogen utilization. He says their new strip-till machine provides beneficial tillage in the root zone that enhances mineralization and nutrient incorporation that they did not get with the coulter cart.
The Schroeders also find assisted steering helps the accuracy of their strip-till operation, especially in wheat and soybean stubble going into corn.
“We’re using an Auto-Trac SF2 system because we’re so committed to the John Deere GreenStar program in all other phases of precision ag. The monitors and satellites are all universally used for everything from yield mapping, field documentation, parallel tracking as well as autosteering,” he explains.