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Corn+Soybean Digest

Space Age Sidedressing Ties N Dose to Weather | New Online Tool Brings New Accuracy Level to N Prescriptions

Space Age Sidedressing Ties N Dose to Weather | New Online Tool Brings New Accuracy Level to N Prescriptions

You can’t control the weather, but you can now watch your N as weather changes.

The same computer modeling technology guiding NASA, engineers and doctors can now assess your crop’s N needs every 24 hours.

The Adapt-N online computer model simulates the complex processes in a corn field: local precipitation and temperatures, soil type, soil organic matter and slope, previous crops, inputs, tillage, planting date, population, hybrids, rotation, type and date of starter and yield potential. Using high-resolution weather information (3x3-mile grids), the web model tailors site-specific N recommendations to your farm in almost real time.

The model was developed by Cornell University agronomists led by Harold van Es.

Adapt-N enables N to be sidedressed as weather events unfold, reducing the application of N early in the season.

“Adapt-N allows you to explore various what-if scenarios, in addition to providing real-time answers during the growing season,” says Jerry Hatfield, director, National Laboratory for Agriculture and the Environment, Ames, Iowa. “You can also replay the growing season and see whether you did the right thing.”

After 1½ years’ testing in Iowa and New York, the Adapt-N online tool became available this growing season in Illinois, Indiana, Minnesota and Wisconsin; and more states next year.

“This was what we needed for the Midwest, so I asked if we could adapt it for Iowa conditions,” says Agronomist Shannon Gomes, owner, Cedar Basin Crop Consulting, part of MGT Envirotec. The group of four Iowa crop consultants conducted 25 replicated Adapt-N trials, each with four replicated strips in 2011 and 2012. “It was especially helpful accounting for the effect of early versus late-planted fields and variable soil organic matter,” Gomes says.

“As a practitioner who’s struggled with N management for 25 years, this is a huge savings over the standard method of taking soil tests for the spring nitrate test, keeping them cool, sending them to the lab, getting the results, interpreting them and making recommendations that are invalid with the next rain,” Gomes says. “The late-spring nitrate test is only a snapshot in time. If you receive a 3-5-in. rain, you should retake the sample. That’s a lot of work for consultants covering 200 fields. Now I can run the Adapt-N model every night and email a client after a weather event and tell him one field needs 80 lbs. more N.

“Besides enabling us to accurately reduce the N rates with this model, we’re also more timely applying it when the crop needs it,” Gomes says.

One MGT Envirotec colleague, Frank Moore, ran two replicated strip trials with Adapt-N, “and they were spot-on perfect,” Moore says. He is an independent agronomist and owner of Three Rivers
Ag Consulting, Cresco, Iowa. “Adapt-N is the only tool that directly incorporates the latest weather information into its N-rate recommendations.”

He tested Adapt-N on his home farm. He is in his third year of strip-till there after 25 years of no-till and ridge-till on corn and beans across heavy clay loams.

“We normally spray about 15 gal. of 28% N with herbicide right after planting and then sidedress another 25 gal. N mid to late June,” Moore says of his corn/bean rotation. His full-season rate is 125-130 total lbs. N/acre.

Adapt-N’s sidedress N recommendations were 25% below Moore’s sidedress rate (56 lbs./acre) in 2011, based on his north Iowa variables.

Despite the 19-lb. sidedress rate difference, both strips across this 35-acre field had precisely the same yield-monitor corn yield: 200.7 bu. “I was amazed; they were spot-on the same yield, and the highest yield this field has had to date,” Moore says.

“That was $8.82/acre worth of N saved, plus 19 lbs./acre N not applied to the environment. “If you have already applied that N, Adapt-N can tell you if it is still there; and if you have not applied your N, it can recommend a rate based on current conditions.”

In 2012, drought conditions affected the corn crop’s fertilizer needs in most areas of the country.  “Although the trial results are not yet available, it is already clear that most fields needed a lot less nitrogen than in a usual year,” van Es says. “Adapt-N could not predict the July droughts and associated yield losses by sidedress time, but it still recommended lower rates than normal by incorporating the dry early-season conditions.”

MGT Envirotec partner Hal Tucker of Tucker Consulting in Storm Lake, Iowa, agrees: “We were able to recommend an average of 40 lbs./acre less N on eight farms in our strip trials, and thereby saved them money in a year when profits are going to be low. Also, Adapt-N tells us how much N remained in the soil at the end of the season.”

Adapt-N is the only N model that accounts for weather events and tells you whether the N you applied earlier is still there, Moore says. “I write a lot of manure plans, and this tool can tell you whether your fall-applied manure nutrients are still there.”


How Adapt-N saved one farm 140 lbs. N/acre

One Adapt-N study showed potential savings of 100 lbs. N/acre for late-planted fields on a western New York farm where soil organic matter ranges widely, from 0.9% to 9.9%. The 2011-12 growing season swung from record spring rainfalls to very dry conditions in June and July.

The farm received more than 6 in. rain in April and again in May 2011.

Because of this record early rainfall, the farm’s average N shortfall for the April-planted corn was 31 lbs./acre, despite the 160-200 lbs./acre already applied. The sidedress-N rate recommendations modestly decreased over time as June and July 2011 weather changed to be very dry, and the likelihood of losses decreased.

The late-planted corn plot had considerable excess N, especially on high organic-matter soils. This reflects too-high preplant N rates for the June-planted corn. Rates could have been reduced by an average of 100 lbs./acre. In this case, planting date was the largest factor affecting N-rate recommendations, says Harold van Es, Cornell University professor of soil and water management and Adapt-N team leader.

The Donalds and Sons Farm, Moravia, N.Y., also used Adapt-N and high-resolution localized weather information in four replicated strips to tailor N recommendations.

They planted corn May 21, 2011 with just 22 lbs./acre N from MAP starter recommended. In early June, their field information, such as organic-matter content, expected yield, tillage and fertilizer inputs, were entered into Adapt-N to generate an N sidedress recommendation of 80 lbs. N/acre, compared to the standard 220-lb. N rate based on the recommendation from their commercial lab.

At harvest, there was no loss in yield despite the 140-lb. difference in sidedress application rates. The Donalds’ yield-monitor data showed spot yields between about 120 and 230 bu./acre, with an average yield for the field of 174 bu./acre and no difference between the N rates.

Assuming the trial field was fairly representative of the rest of the farm, the Donalds would have saved approximately $70,000 in 2011 fertilizer, van Es says.  A post-season Adapt-N simulation estimated that they also reduced their N leaching losses in 2011 by about 77%, from 142 to 32 lbs/acre.



Adapt-N adjusts N recommendations in real time

Web-based decision support tool provides field-specific N recommendations in real time, in-season.

  • Suited for desktop, tablet or smartphone (browser).
  • Computer model reflects latest weather conditions, soil type and plant-N-uptake physiology model every 24 hours. Modifies recommendations as weather and field conditions evolve, in real time.
  • Determines if manured fields need additional N.
  • Determine if you need rescue N after heavy spring rains, and/or as other variables change.
  • Identifies remaining N after the growing season.
  • Improved corn-growing profits in 86% of 2011 trials, by an average of $35/acre.
  • Enables what-if planning.
  • Available this year in Iowa, Illinois, Indiana, Minnesota, Wisconsin and the Northeast.
  • One New York pilot farm had a 140-lb./acre N rate difference between conventional recommendation methods, with no lost yield. The same site also reduced its 2011 N leaching losses by about 77%, from 142 to 32 lbs./acre.
  • Replicated trials in Iowa decreased N rates by 45 lbs./acre on average and increased grower profits in 78% of cases. N losses to the environment were decreased by 5-120 lbs./acre.
  • Adapt-N has been presented at conferences held by the North Central Extension-Industry Conference, the National Alliance of Independent Crop Consultants, the Iowa Soybean Association On-Farm Network, Iowa State University’s Integrated Crop Management, the Soil and Water Conservation Society and the American Society of Agronomy.


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