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More Corn, Less N

October 26, 2010
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Filter strips line the ditchbanks of Doug (left) and Jeff Martin’s farm. Other stewardship practices they use are no-till and strip-tilled continuous corn and precision technology.  
 
 

As they plant, as they harvest, as they plan for next season, in the back of Jeff and Doug Martin’s minds is one goal: More corn from less fertilizer. “We think we can eventually produce a bushel of corn from ¾ lb. of applied nitrogen,” Doug says.


The father-son team, which farms near Mount Pulaski, Ill., applies 1 lb. of nitrogen per bushel of anticipated yield. Not long ago, they were applying the traditional 1.2 lb. per bushel.
Among the tools the Martins use to reduce rates while they increase yields are nitrogen-efficient hybrids and their long-term no-till/strip-till program. Doug’s father, Jeff, thinks converting from a corn/soybean rotation to continuous corn on most of their acreage is helping, too.
“With continuous corn, I think we’re seeing more nitrogen being mineralized from the soil,” he says.
 

Their efforts to grow more corn with less fertilizer led to the Martins being named Upstream Heroes by the Conservation Technology Information Center (CTIC). The CTIC wants to demonstrate that high yields, increased profitability and sound nutrient management go hand in hand.


Making sure fertilizer is used by crops, and not allowed to escape into water supplies, is important for the environment as well as for a farm’s bottom line, says CTIC
executive director Karen Scanlon. Nitrogen and phosphorus flowing down the Mississippi River into the Gulf of Mexico contribute to hypoxia, she explains. Excess nutrients result in blooms of algae that deplete the water of oxygen when they decompose, creating a “dead zone” where sea creatures can’t live.

No-till and continuous corn. Continuous no-till cropping helps prevent nutrients from being lost through soil erosion and runoff, says consultant Dan Towery, who operates Ag Conservation Solutions in Lafayette, Ind. “Key to the Martins’ success with no-till and continuous corn was doing their homework before they started, keeping a positive mindset, starting on a modest scale and expanding only as they became comfortable with each practice,” Towery says.
 

Some of the Martins’ fields haven’t seen a traditional full-width tillage tool, such as a moldboard plow, chisel or field cultivator, for 25 years, except for spot-tillage to fix ruts created during wet harvest seasons. Some of them have been in continuous strip-till corn for six years.
 

Continuous corn yields as well or better than rotational corn, the Martins say. That echoes two yield champions, the late Herman Warsaw and the late Francis Childs, who grew record yields with conservation tillage (although not no-till).
 

Strip-tilling corn on 90% of their acres required the Martins to change no-till and fertilizer application techniques, but nothing that jeopardized soil quality or reduced fertilizer efficiency, Towery says.

Managing residue. Continuous corn requires managing more crop residue. Residue on the surface protects soil from erosion, and the soil tests of yield champions Warsaw and Childs suggest that, in time, continuous corn and conservation tillage can increase soil organic matter content. But a blanket of residue also can keep soil cold and wet, interfere with seed placement and affect nutrient cycling.
 

For the Martins, the solution to residue was fall strip-tilling, which creates a mellow seedbed that dries out for timely planting. To size residue and eliminate plugging as they build strips, they run a Salford RTS (Residue Tillage Specialist), a shallow secondary-tillage tool, over the field.
As an advocate of 100% no-till, Towery wants to see as little soil disturbance as possible. “But you have to do what’s necessary to get a good, picket-fence stand of corn,” he says.


“The Salford helps size residue and hasten the breakdown of Bt cornstalks, which are slower to decay,” Towery says. “Just don’t use it unless you need to. I’ve seen farmers make two passes over soybean residue, and that may be one more than they really needed. On well-drained soils, or in drier areas such as the western Corn Belt, you can no-till directly into soybean residue if you have the proper planter setup.”

Conservation Programs Protect Water, Profit

Besides continuous no-till, the way Jeff and Doug Martin keep nutrients from escaping into water supplies is by removing hard-to-farm, erosive land from crop production. They and their landlords have enrolled about 600 acres in USDA’s Conservation Reserve Program and in a state/federal version called the Conservation Reserve Enhancement Program.

"We used those programs to plant filter strips along streams and drainage ditches, create shallow-water wetlands and plant grass strips around field edges," Jeff explains. "We have placed permanent conservation easements on two farms that we own."

Their management of natural resources made it easy for the Martins to enroll in the Conservation Stewardship Program (CSP) when it was offered in their area. CSP offers payments for conservation practices already in place. "We didn’t have to change anything to qualify for CSP," Jeff says. "We had to agree to do integrated pest management—scouting crops and spraying based on threshold populations of pests. But we already were doing that—we just had to start documenting our activities."

 

High-residue applicator. In cornstalks, the Martins think their John Deere 2510S anhydrous ammonia applicator, designed for high-residue conditions, may eliminate the need to size residue. “We would prefer to leave the residue untouched before strip-tilling,” Jeff says. “If it rains after you cut the residue, the pieces can wash away or form mats in low spots.”
When they rotated corn and soybeans, the Martins sidedressed their nitrogen fertilizer right after planting in order to get over corn acres in a timely fashion. But their increased corn acreage required a switch to anhydrous ammonia applied in the fall, as they build their strips.
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Spoon-feeding, with sidedressing as the main application method, is the most efficient way to apply nitrogen, Towery says. “Generally, you can apply about 20% less nitrogen fertilizer if you sidedress, compared to fall application,” he says. “But if you have to fall-apply ammonia, there are ways to minimize losses of nitrogen. Wait until the soil temperature reaches 50°F and remains there. Add N-Serve nitrogen stabilizer to reduce the risk of leaching or volatilization.”
The Martins adhere to those practices religiously. “We don’t want to waste money, and we don’t want fertilizer getting into water supplies,” Jeff says. “While agriculture is not the only contributor to hypoxia in the Gulf of Mexico, we’re concerned about the public’s perception of farmers and our role in protecting the environment.”
 

On wetter fields, where nitrogen is most likely to be lost, the Martins side-dress their nitrogen fertilizer.
 

Depending on the situation, the Martins’ fields also receive 5 lb. to 10 lb. of 28% solution nitrogen per acre, applied as a herbicide carrier.


All told, the Martins’ usual continuous-corn fertilizer program includes 170 lb. to 190 lb. of anhydrous ammonia per acre, 18 lb. as DAP (if phosphorus is needed) and 5 lb. to 10 lb. in their weed-and-feed treatment. So, depending on the field, their maximum total application
is 218 lb. of nitrogen per acre, and sometimes less. With normal weather, they expect to grow 220-bu. corn in most fields.


“That’s the same amount of nitrogen we used to apply when our yield goal was only 180 bu. per acre,” Doug says.
 

With corn following soybeans, the Martins sidedress 120 lb. to 150 lb. of nitrogen per acre.

No-till tools and techniques. Row cleaners are a must for planting on strips, the Martins say. But strip-till eliminates the need for no-till coulters. They use a Raven rate controller for anhydrous ammonia application.
 

It’s important to prepare soil before moving into a no-till/strip-till program, they add. When they acquire new land, they remove compaction and build up soil pH and fertility levels before beginning to no-till or strip-till.

They also try to improve drainage. “Good drainage is critical for a high-yield environment,” Jeff says. “Many of our fields are tiled and we have a plan to continue tiling where it is needed.”
The Martins choose hybrids carefully and use triple-stack GMO hybrids for insect control. “Controlling pests results in larger root mass and better utilization of nutrients,” Jeff says.
RTK auto-guidance makes strip-till more effective and easier. “We use auto-guidance for strip-tilling and planting,” Jeff says. “Side draft on the planter was pulling it off the strip, so we added John Deere’s iGuide system to compensate for implement drift.


“I’ve read that getting 1,000 plants per acre off the tilled strip reduces yield by 7 bu. per acre. Keeping every kernel in the strip is making us a lot of money,” he adds.
 

Backup Plan for Wet Conditions
Until last year, Jeff and Doug Martin always got strip-till and ammonia application done in the fall.
“In 2009, the soil was too wet to seal after ammonia application,” Jeff says.
The Martins had a backup plan, however. They had already run their Salford tool over their cornstalks in the fall of 2009. In spring, 2010, they took two approaches.
In some fields, the Martins had ammonium sulfate
custom-applied. In fields where soil tests called for phos-phorus, they also applied diammonium phosphate (DAP). They made one pass with their Salford tool and no-tilled corn, using a planter equipped with row cleaners.
In other fields, they ran the Salford tool in the spring, then strip-tilled and applied anhydrous ammonia at an angle to the rows. That reduced the number of corn plants placed directly over ammonia, which can burn seed when applied too close to planting.
Strip-tilling in the spring gave the soil less time to settle, creating the risk of a less-than-perfect seedbed. “Because we got a lot of rain right after planting, everything worked out OK,” Jeff says. “We’ll be glad to get back to our regular program in 2010.”

 

Besides protecting the environment and their own profitability, the Martins see other advantages to their farming style. “Landowners tell us they watch the way we farm,” Doug says. “I think we’ve picked up some farms because of our conservation practices.”


You can e-mail Darrell Smith at dsmith@farmjournal.com.

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FEATURED IN: Farm Journal - November 2010
RELATED TOPICS: Agronomy, Water, Upstream Heroes

 
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