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This article in AJ

  1. Vol. 86 No. 5, p. 921-923
    Received: Sept 13, 1993

    * Corresponding author(s):
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Calculation of Optimal Nitrogen Fertilizer Rates

  1. David S. Bullock and
  2. Donald G. Bullock 
  1. D ep. of Agric. Economics, 1301 W. Gregory Dr.
    D ep. of Agronomy, 102 S. Goodwin Ave., Univ. of Illinois, Urbana, IL 61801



Agronomists sometimes fail to apply sound economic theory when recommending economically optimal nitrogen fertilizer application rates. Producers' objectives, producers' attitudes toward risk, and the effect of N on second and higher moments of the yield distribution are often left unstated or ignored. If a farmer knew, prior to N application, the future values of all stochastic factors that affect yield response to N during the growing season, optimal N rates could be established for each individual site-year. However, farmers do not have perfect knowledge, so recommended rates should not change from year to year for a given site. We propose a more economically sound method for deriving economically optimal N fertilizer application rate recommendations. Our method maximizes profit on average over observed years for a given site. Long-term field experiments from Illinois demonstrate that our proposed method increases profit from a trivial $0.18 ha−1 yr−1 to a substantial $103A1 ha−1 yr−1, depending on site and cropping sequence. We call for increased collaboration among agronomists and agricultural economists in the economic analysis of fertilizer application.

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