Nitrogen test plots confirm that timing matters
Ahigh percentage of the Farm Journal Test Plots revolve around one key nutrient—nitrogen.
"Time and time again, we see that nitrogen is king—it makes the biggest difference," explains Farm Journal Field Agronomist Ken Ferrie. "The nitrogen cycle is complex, but the first thing farmers must understand is that finding the right nitrogen timing, placement and rate requires more than using the simple equation of bushels per pound of nitrogen."
To shape their nitrogen management program, Ferrie encourages farmers to consider product in addition to timing, placement and rate. Comparing programs that use different sources of nitrogen at different times is like comparing apples to peaches.
The Farm Journal Test Plots have found no difference in yield when applying anhydrous ammonia or 28% when positioned the same way. (See "Bridge the Gap," Late Spring 2013.) Ferrie continues to learn more about how the variables in a nitrogen plan add up to yield success and how to fill in the weak spots of a nitrogen program.
"The goal is to find out how farmers can make their nitrogen dollar go as far as possible," Ferrie says. "In 2013, we saw 20 bu. to 60 bu. yield hits because we didn’t manage nitrogen effectively."
The right placement. This past year, Ferrie and his crew conducted two test plots focusing on nitrogen placement.
The first test plot, in its second year in 2013, is a season-long effort that compares four timings of nitrogen application: pre-emergence broadcast, preplant strip-till, nitrogen applied with the planter and sidedress nitrogen. The strip-till treatments were applied with a Great Plains Nutri-Pro toolbar with coulters 8" apart, placing the banded nitrogen 4" on both sides of each row and 3" from the surface. The nitrogen applied at planting included in-furrow starter fertilizer as well as 28% applied 2" to the side and 2" below the surface. The same total rate of nitrogen was applied overall but at different timing combinations.
In each field, the application and planter passes were made with RTK accuracy to ensure exact placement of nitrogen and seed.
The first year, 2012, included two corn-on-corn fields. "That was a tough year to start a plot because of the weather and environment, but we saw that the field was responding to the banded nitrogen. The more we banded, the stronger the response—with strip till, planter applied and sidedress banding being the strongest. On the flip side, the more we broadcasted, the more yield decreased," Ferrie explains.
As suspected, it quickly became clear that the environment matters. From central Illinois and north, Ferrie advocates for farmers to broadcast some nitrogen in heavy residue conditions to help decompose residue faster.
"In heavy residue fields, farmers must deal with the carbon penalty. Sometimes this can be done with broadcast, but when we combine broadcast with banded applications, we weatherproof a nitrogen program," Ferrie says. "Strip-till and nitrogen applied with the planter bypass the carbon penalty by keeping the plant happy while the microbes immobilize nitrogen to decompose the residue. Due to timing, those placements decompose less surface residue and are less susceptible to nutrient loss."
To verify results, all Farm Journal Test Plots are harvested with calibrated yield monitors, and each load is weighed with grain carts with scales.
Application timing depends on geography as well. Ferrie notes that Southern farmers who want to conserve residue should consider banded applications because they don’t speed up decomposition of surface residue.
When plants need it. After thinking about the planting environment, farmers should also consider the timing of their applications.
"When I talk about timing of nitrogen applications, I don’t necessarily mean when I apply but when does the plant need it," Ferrie says. "Farmers have to make sure the plant is happy from the beginning to the end and remember the environment sets the tone. For example, in corn on corn, front-end timing is key to manage the carbon penalty."
If plants get behind because there is not enough nitrogen when needed, there’s no way for them to catch up.
A nitrogen program should supply the corn with what it needs up-front to keep the plant from slowing down in the early growth stages.
For example, all up-front broadcasted nitrogen might look good in the beginning, but it doesn’t have the staying power as the same amount banded. In addition, the risk of loss is higher when nitrogen is applied too far in advance of the growing crop.
In 2013, two fields were part of the nitrogen placement plot—one corn on corn and the other corn after soybeans. Including two crop rotations allowed Ferrie to evaluate the different nitrogen demands as well as seedbed preparation when running a Nutri-Pro toolbar.
"The question becomes that if there are advantages to banding nitrogen with the strip-till toolbar, could it also eliminate the spring pass of a vertical tillage harrow in preparing the final seedbed," he says. "So there’s a dual benefit to that pass over the field."
In the corn-after-soybeans field, 220 lb. of nitrogen was applied broadcast, strip-till, at planting and sidedress. Some treatments were increased to 280 lb. to ensure that nitrogen wasn’t the limiting factor.
"In a heavy soil type where we side- dressed the full 220 lb. compared to shifting 30 lb. to the planter and sidedressing the remainder, we gained more than 30 bu.," Ferrie says. "There was a big payoff to supply the corn plant with nitrogen banded at planting.
"We were also able to pay the carbon penalty from the soybean residue," Ferrie adds.
On an entire field average, the preplant treatments with some of the nitrogen allotment banded with the strip-till toolbar were the highest yielding in the plot. The next four highest-yielding treatments included some of the nitrogen allotment being applied with the planter.
At the second location, the corn-on-corn field was divided into two zones—one with a high pH and one with a normal pH. As a base nitrogen application in March, 100 lb. of nitrogen as AMS was applied to the normal pH zone. In the higher pH zone, the rate was increased to 160 lb. of nitrogen as AMS.
Then 90 lb. of nitrogen was divided into treatments, including strip-till, pre-emergence broadcast (with UAN) and sidedress.
"In the high pH zone, we increased yields 38 bu. when 90 lb. of nitrogen was applied with the strip-till toolbar compared with surface broadcasting the total nitrogen allotment," Ferrie says.
Due to the wet spring, he believes that broadcasting the nitrogen led to it being moved further down in the soil profile and out of the reach of the small corn plant when it was caught in the carbon penalty. Banding the nitrogen kept the nutrient within reach.
The pre-emergence, broadcast UAN application was not incorporated or applied with an inhibitor, so in the high pH zone with a higher water-holding capacity, that might have led to volatilization.
"That’s another example of how environment impacts the effectiveness in timing nitrogen applications," Ferrie says.
In addition, he believes that the nitrogen rates in the normal pH zone might have not been high enough because that area of the field repeatedly outyields the high pH area.
The observations from the 2013 banded nitrogen applications echo the lessons learned from the starter fertilizer—inches do matter. The greatest yield success comes from keeping the corn plant happy by banding fertilizer so it’s available as the roots grow.
Sidedress options. The second nitrogen placement plot in 2013 focused on testing a new fertilizer attachment.
The Y-Drop applies nitrogen on a self-propelled sprayer.
"This concept puts nitrogen in what I call the stem water zone," Ferrie says. "The corn plant is set up to self-irrigate by keeping the soil moist around the base of the plant and the crown roots alive. If you go out after a heavy dew, you’ll see the wet rings around the base of the plant."
Ferrie says that by putting nitrogen in the stem water zone, there’s a greater chance that moisture will move the nitrogen into the plant.
In two locations, the crew used three treatments at V6. The same rate was applied at the same timing, so the crew was able to evaluate the placement aspect of sidedressing.
The treatments included the Y-Drop attachment, a traditional drop nozzle design using VeriFlow nozzles, and a standard sidedress toolbar with knives. The crew completed the sprayer passes and then returned one day later to sidedress the remaining treatments in the field.
"This was first-year data," says Brad Beutke, who ran the applicators and works in the Farm Journal Test Plots. "But it was encouraging in that the Y-Drop performed with the same yield response or slightly above the traditional sidedress."
With a self-propelled sprayer, the Y-Drop applies nitrogen like a sidedress program.
Beutke explains that using a high-clearance sprayer could provide farmers with an additional 10 days in their working window. The Test Plot crew intends to continue studying machines to sidedress corn.
Weather factor. Anytime a nutrient is banded and positioned for timely uptake, efficiencies will be gained.
"But seasonal weather impacts your nitrogen program," Ferrie says. "This past year, broadcast applications struggled due to the wet spring that pushed planting into May. That had an adverse affect on soil surface nitrates."
Typically the nitrate levels in the second foot of soil are one-half or one-third of the top foot, he explains. But in 2013, due to spring rains, the soil nitrate level in the second foot was almost higher than in the first foot.
"This indicated the nitrates moved down in the soil profile. While not lost, they were too far away to help with early season growth," Ferrie says.
While it’s critical to plan out a nitrogen program, it’s equally key to be flexible enough to adjust when the weather throws a curve ball. This could mean adding nitrogen to the planter or following up with extra sidedress applications.
"Remember, when we add banded nitrogen to the planter, we weatherproof a program," Ferrie says.
Thank You to Our Test Plot Partners
Each Farm Journal Test Plot is a cooperative effort. Thanks go to: Yetter Corporation and Scott Cale; Great Plains Manufac-turing, Tom Evans and Doug Jennings; Case IH, Dan Klein, Kyle Russell and Ryan Schaefer; Central Illinois Ag and Kip Hoke; Kinze Manufacturing, Suzanne Veatch and Luc Van Herle; Unverferth Manufacturing and Jerry Ecklund; LeRoy Fertilizer and Bob Spratt; Y-Drop and Dan Muff; ACRE and Brian Sutton; McLaughlin-Dooley Farms; Al Reeser; Rod Wilson; Crop-Tech Consulting, Isaac Ferrie and Brad Beutke.
You can email Margy Eckelkamp at email@example.com.