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This article in AJ

  1. Vol. 96 No. 6, p. 1572-1580
    Received: Aug 25, 2003

    * Corresponding author(s): rkhosla@colostate.edu
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Economic Feasibility of Variable-Rate Nitrogen Application Utilizing Site-Specific Management Zones

  1. B. Kocha,
  2. R. Khosla *a,
  3. W. M. Frasierb,
  4. D. G. Westfalla and
  5. D. Inmana
  1. a Dep. of Soil and Crop Sci., Colorado State Univ., Fort Collins, CO 80523
    b Dep. of Agric. and Resour. Econ., Colorado State Univ., Fort Collins, CO 80523


Variable-rate technology (VRT) has been developed to variably apply crop inputs to manage in-field variability. Although growers have begun to adopt VRT, its profitability is uncertain in N management. The objective of this study was to assess the economics of uniform vs. variable-rate N fertilizer application under two N application scenarios (farmer vs. custom applications). On-farm studies were conducted on two continuous corn (Zea mays L.) fields in northeastern Colorado under furrow and center-pivot irrigation during the 2000 and 2001 growing seasons. The N management strategies were uniform, grid-based, site-specific management zone–constant yield goal (SSMZ-CYG) and site-specific management zone–variable yield goal (SSMZ-VYG). “Profit and loss” software was used to analyze the economics of each N management strategy and determine which N strategy was most profitable. Results from three site-years consistently indicated that less total N fertilizer (6–46%) was used with the SSMZ-VYG N management strategy when compared with uniform N management. Net returns from the SSMZ-VYG N management strategy were $18.21 to $29.57 ha−1 more than uniform N management. Results of this study suggest variable-rate N application utilizing site-specific management zones are more economically feasible than conventional uniform N application.

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