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Adapt-n for efficiency
Choosing a nitrogen rate for corn ahead of the growing season is like planning a Fourth of July picnic in January. There is no way of knowing if the weather will ruin your plans.
Harold van Es, a soil scientist and professor at Cornell University in New York, believes weather holds the key to managing nitrogen (N).
That belief led him and colleagues at Cornell to develop a new Web-based tool called Adapt-N that accounts for field-to-field and year-to-year variability in the availability of nitrogen in the soil. It's a form of adaptive management that enables growers to adjust rates from year to year based on local conditions, especially weather conditions.
“Corn N fertilizer needs cannot be predicted accurately at the beginning of the growing season due to weather variability during the critical period in spring,” says van Es. “Excessive precipitation causes soil N losses through leaching and denitrification, resulting in higher supplemental N fertilizer needs and increased pollution.”
Research shows the amount of nitrogen needed by a corn crop can vary by 100 pounds per acre or more from one year to the next.
Jeff Melkonian is a senior research associate at Cornell and a member of the team who developed the Adapt-N tool. He says, “In warm weather, nitrogen mineralizes faster from organic matter in the soil to become available to the corn, while the opposite is true in colder weather. In a drier spring, nitrogen mineralizes and remains in the root zone where the corn can take it up, while in a wetter year, the nutrient may leach out of reach of the crop roots.”
A third team member is Bianca Moebius-Clune, an Extension associate at Cornell. She says, “The Adapt-N tool provides growers with more precise, field-specific nitrogen recommendations based on the impact of early-season weather.”
It was beta-tested on a few farms in New York and Iowa in 2010 and 2011, and it will be used in additional states in the Northeast and Midwest this year.
“The Adapt-N tool represents a new approach in decision management by combining the use of the precision nitrogen management (PNM) model with the most up-to-date high-resolution climate data,” says Melkonian. “It involves advanced computational methods that can be employed through a relatively simple Web interface.”
The Adapt-N tool provides in-season nitrogen recommendations based on model simulations of soil N dynamics and corn nitrogen uptake. It was developed as part of the Computational Agriculture Initiative, supported by a special grant from USDA-NIFA.
Adapt-N is a Web-based decision tool that links to daily high-resolution climate data (on a 3-mile grid) made available by the Northeast Regional Climate Center. It was designed to account for daily weather influences and expected economic yield to calculate sidedress N recommendations for individual fields.
According to the Adapt-N developers, “the prediction of nitrogen needs becomes more accurate as the season progresses because more of the season's weather is then known.”
Participating growers enter latitude and longitude for their fields, along with soil texture and organic matter content, tillage, past manure application information, and other data into the online tool at http://adapt-n.cals.cornell.edu. The researchers working with the Adapt-N tool say using localized information provides more precise estimates of N needs.
Adapt-N uses the data entered by the grower to calculate a recommended optimal nitrogen application rate or the amount of excess N available to the crop.
It's best to access the nitrogen recommendations the day nitrogen is to be applied. “The model is then run in real time and outputs a recommended N sidedress rate,” says Melkonian. “The tool also provides users with information on changes in soil N and crop N uptake.
“A key feature of Adapt-N is that it accounts for changes in soil N due to early-season weather and adjusts the in-season N recommendations accordingly,” says Melkonian. “In-season fertilizer recommendations become more precise as the season progresses.”
Adapt-N can be used on manured fields as well as fields that don't receive manure. The tool fits especially well with sidedress applications when early-season weather conditions can be accounted for.
“The Adapt-N tool and the under-lying PNM model have been calibrated and tested for manured and nonmanured corn-production systems for a range of soil types and weather conditions,” says van Es. “Simulating early-season soil N changes with high-resolution climate data, therefore, allows for quite precise estimates of sidedress N needs and can improve N-use efficiency in corn.”
Last year, brothers Robert and Rodney Donald of Moravia, New York, compared the Adapt-N tool to their standard N program, which is to sidedress most of their N based on soil-test results and recommendations from a private lab.
At corn planting on May 21, they applied 22 pounds of nitrogen in starter. Then in June, they divided 10 acres into eight replicated strips. Four of the strips received 220 pounds of sidedress nitrogen based on the recommendations from the private lab. The other four strips received just 80 pounds of sidedress nitrogen, which was the rate determined by using the Adapt-N tool.
The average yield for the four strips that received 220 pounds of sidedress nitrogen per acre was 174.1 bushels per acre. The average yield for the four strips that received the Adapt-N recommendation of 80 pounds of sidedress nitrogen per acre was 173.6 bushels per acre. Similarly, 86% of New York trials showed increased profits when using Adapt-N recommendations.
The Cornell researchers view Adapt-N as a win-win opportunity. Better weather-adjusted N management will allow for adaptation to and mitigation of climate change, lower environmental losses, and higher profits.