You can now assess your corn’s nitrogen (N) needs every 24 hours. The Adapt-N online computer model, from Cornell University, 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.

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.”

The most recent 2012 Adapt-N results from Iowa show 36-lbs./acre average N input reductions, with no significant yield reductions in 95% of the cases. These data come from 19 (drought year) 2012 Iowa trials. There was a profit advantage over conventional N rates in 74% of the trials (by $1.49-$81.20/acre).

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“Adapt-N could not predict the July Iowa droughts and associated yield losses by sidedress time, but it still recommended lower rates than normal by incorporating the dry early-season conditions.”

Over the 2012 growing season, 61 trials indicate that:

  • Grower profits increased on average by $17/acre in Iowa trials and by $32/acre in New York with the improved 2012 Adapt-N model version.
  • N application rates were significantly reduced in almost all cases, by 54 lbs. N/acre on average, substantially reducing post-growing season losses of excess N to the environment.
  • Any yield losses were generally negligible (minus 1 bu./acre average across all trials), despite the reduced N inputs
  • Higher N recommendations were justified by higher yields when drought was not the greater limiting factor.
  • 77% of Adapt-N recommendations provided increased grower profits over current rates in 2012, when including inadequate expected yield inputs; 87% when these are excluded.
  • Model inputs, especially yield expectation, must be carefully chosen to represent field-specific conditions.

In all, growers can realize large savings with the use of Adapt-N, which also provides strong incentives to shift the bulk of N applications to sidedress time, and will decrease long-term environmental losses.

More Adapt-N Trials, Results

Agronomist Shannon Gomes, owner, Cedar Basin Crop Consulting, part of MGT Envirotec, tested Adapt-N in 2011 and 2012. The group of four Iowa crop consultants conducted 25 replicated Adapt-N trials, each with at least four replicated strips. “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,” he says.

“It was especially helpful accounting for the effect of early- versus late-planted fields and variable soil organic matter,” 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.

MGT Envirotec partner Hal Tucker of Tucker Consulting in Storm Lake, Iowa, who tested Adapt-N, was “able to recommend an average of 40 lbs./acre less N on eight farms in our strip trials. Also, Adapt-N tells us how much N remained in the soil at the end of the season.”

Another MGT Envirotec colleague, Frank Moore, Cresco, Iowa, ran two replicated strip trials with Adapt-N, “and they were spot-on perfect,” he says. He is an independent agronomist and owner of Three Rivers Ag Consulting.

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 soybeans 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.

In 2011, Adapt-N’s sidedress N recommendations were 25% below Moore’s sidedress rate (56 lbs./acre), 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.”

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.”

More detailed Adapt-N trial results are at

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