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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.