If there ever was a time to consider nitrogen choices other than anhydrous ammonia, this might be one of them, says Piper City, Ill., strip-tiller Brandon Grubbs. With dry conditions still affecting much of the Corn Belt, strip-tillers need enough moisture in the soil so it seals in the anhydrous, says Grubbs, who also co-owns a fertilizer and chemical business.
Grubbs strip-tills with a 12-row Twin Diamond Strip-Cat and also sells Strip-Cats and Montag dry fertilizer carts. He doesn’t use anhydrous ammonia and says anhydrous use is on the decline in his area.
It was wet last May and then dry for much of the summer in the area.
“We’ve pretty much had normal rainfall since late August,” Grubbs says. “Conditions will be good for strip-tilling later this fall if we continue to get some moisture. But further north of us, applying anhydrous ammonia will be a challenge this fall.”
Some of the farmers who do use anhydrous in the fall will apply 100 pounds and then sidedress in the summer, Grubbs says. Larger farmers are either applying much of their nitrogen in the fall or applying 100% of their nitrogen in the spring, pre-plant applying 28% liquid nitrogen, he says.
While fall strip-tillers who apply anhydrous in the fall may be concerned about the dry soil sealing, Grubbs says it could also be good to remember next summer what happened in some corn fields that were sidedressed with anhydrous in the summer of 2012.
“Because it was dry when some farmers sidedressed anhydrous, the corn root burn showed that this is a really good way not to grow a good corn crop,” he says.
Fall And Spring Strip-Till
Grubbs believes the soil will mellow out this fall, which will be good for strip-tilling. When he strip-tills in the fall, he doesn’t use the basket attachment on the back of his Strip-Cat, but says the baskets do help in the spring.
WATCH POTASH LEVELS. This year’s dry conditions likely revealed potash deficiencies. Piper City, Ill., strip-tiller Brandon Grubbs says the addition of potassium thiosulfate in sidedress applications have improved corn yields by 6 to 30 bushels per acre in test plots.
When strip-tilling in the spring, Grubbs likes using three coulters on each row unit. He used the three-coulter system in the spring of 2010 to strip-till after wet conditions kept him from strip-tilling in the fall of 2009.
“The spring strip-tilled corn with the three-coulter system was my best corn in 2010,” he says. “Some of my landlords worry about strip-tilling corn-on-corn, but it can work well.”
He strip-tills about 40% of his corn-on-corn acres and all of his corn after soybeans.
While Grubbs hasn’t harvested any of this year’s strip-tilled corn, it looks better than conventionally tilled corn in the area. He believes strip-tilled corn fields retained more moisture during weeks and months of heat vs. conventionally tilled fields with little residue protection.
In 2010, Grubbs harvested 230-bushel-per-acre strip-tilled corn. In 2011, he averaged about 170 bushels per acre after a dry growing season. This year, corn yields are incredibly variable in eastern Illinois.
“We were in an area in eastern Illinois that was on edge of where it started raining,” Grubbs says. “Yields are all over the board. On the west side of Piper City, I harvested corn that yielded less than 90 bushels per acre. But on the east side of town — which only has 900 people — the corn averaged 170 bushels per acre.”
Potash Crucial In Dry Soil
Grubbs has seen excellent yield results in corn fields where he sidedressed 32% liquid nitrogen (UAN) along with potassium thiosulfate.
“When you fall-apply nitrogen, your corn can only take up so much of it,” he says. “But when you sidedress more than 100 pounds of UAN per acre, your corn has access to that as soon it gets down in the soil and into the root zone. Corn has to have potash to convert nitrogen so it’s available to the corn plant.”
Last spring, Grubbs pre-plant applied 30 gallons of 28% UAN on his corn ground. When he sidedressed corn, he applied 28% liquid nitrogen with 3 gallons of 0-0-25-17 (potassium thiosulfate).
“Potash levels in the area’s soils have been dropping rapidly,” Grubbs says. “In dry conditions, the corn can take up the sidedressed nitrogen much more rapidly than the potash in the soil. By including the potassium thiosulfate with the UAN, the corn can use the potash right away, no matter what the weather is like.”
Last spring and summer were the driest he’s seen in years.
“We saw some severe potash deficiency this year,” Grubbs says. “It appeared where farmers applied a heavy amount of nitrogen before planting and then sidedressed nitrogen. Potash deficiency shows up quickly when it’s dry because the nitrogen can’t convert the potash. The deficiency is noticeable where there was sidewall compaction and limited corn root mass.”
Phosphate uptake is important early in the growing season for corn and then later in the season when it helps corn fill for better test weight, Grubbs says.
“Farmers who have fields with very low phosphate levels will likely have lower test weight and wetter corn,” he says.
Grubbs says he’s pleased with the results where he tried potassium thiosulfate last summer.
“We harvested a test plot of corn a week ago and saw a response from 6 to 30 bushels and the corn was 1 to 1.5 points drier than the check,” he says. “We had five replications in the same field of corn. The corn where we sidedressed with the potassium thiosulfate had better plant health, but it dried down faster and was drier than the check.”
Fall Fertilizer Program
Two to 4 weeks before strip-tiling in the fall, Grubbs sprays corn stalks with 20 to 30 gallons per acre of 8-0-0-9, mixed with dicamba and 2,4-D, on about half the strip-tilled corn-on-corn acres.
“Because it’s liquid, we can cover all of the residue,” Grubbs says. “It’s really evident in the spring where you applied liquid AMS to the corn stalks because there’s a lot less residue remaining.”
Grubbs uses a knife when strip-tilling in the fall and coulters for spring strip-till. When strip-tilling in the fall, he variable-rate applies DAP, potash and AMS in bands. The range is 100 to 125 pounds per acre of DAP, 25 to 100 pounds per acre of potash and about 25 pounds per acre of AMS.
“The balance is made up using a spinner-spreader with variable-rate technology to fill in the low spots,” he says. “The variable-rate recommendations are made taking previously applied material into account.”
Grubbs uses a base blend of AMS, phosphate and potash, depending on whether it’s corn following soybeans or corn on corn. He accounts for these differences in the variable-rate recommendations. He doesn’t band a huge amount of potash in the fall because sandier soils will not hold it well.
“You need to broadcast some potash,” Grubbs says. “Maintaining potash levels is tough. In the continuous corn that we’ve strip-tilled in the last 5 to 6 years and banded the fertilizer, it’s been amazing how fast the phosphorus levels have increased. For corn following soybeans and corn on corn, we place the fertilizer 6 to 7 inches deep.”