Strengths and Limitations of Nitrogen Rate Recommendations for Corn and Opportunities for Improvement
2018
Morris, Thomas F. | Murrell, T Scott | Beegle, Douglas B. | Camberato, James J. | Ferguson, Richard B. | Grove, John | Ketterings, Quirine | Kyveryga, Peter M. | Laboski, Carrie A.M. | McGrath, Joshua M. | Meisinger, John J. | Melkonian, Jeff | Moebius‐Clune, Bianca N. | Nafziger, Emerson D. | Osmond, Deanna | Sawyer, John E. | Scharf, Peter C. | Smith, Walter | Spargo, John T. | van Es, Harold M. | Yang, Haishun
CORE IDEAS: Nitrogen recommendations for individual corn fields are less accurate than desired.Nitrogen recommendations need improvement for economic and environmental reasons.A review of fundamental concepts will improve understanding about N recommendations.Examination of N recommendation systems, tests, and models will improve recommendations. Nitrogen fixation by the Haber–Bosch process has more than doubled the amount of fixed N on Earth, significantly influencing the global N cycle. Much of this fixed N is made into N fertilizer that is used to produce nearly half of the world's food. Too much of the N fertilizer pollutes air and water when it is lost from agroecosystems through volatilization, denitrification, leaching, and runoff. Most of the N fertilizer used in the United States is applied to corn (Zea mays L.), and the profitability and environmental footprint of corn production is directly tied to N fertilizer applications. Accurately predicting the amount of N needed by corn, however, has proven to be challenging because of the effects of rainfall, temperature, and interactions with soil properties on the N cycle. For this reason, improving N recommendations is critical for profitable corn production and for reducing N losses to the environment. The objectives of this paper were to review current methods for estimating N needs of corn by: (i) reviewing fundamental background information about how N recommendations are created; (ii) evaluating the performance, strengths, and limitations of systems and tools used for making N fertilizer recommendations; (iii) discussing how adaptive management principles and methods can improve recommendations; and (iv) providing a framework for improving N fertilizer rate recommendations.
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