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This article in AJ

  1. Vol. 94 No. 4, p. 815-820
     
    Received: Aug 7, 2001


    * Corresponding author(s): wrr@mail.pss.okstate.edu
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doi:10.2134/agronj2002.8150

Improving Nitrogen Use Efficiency in Cereal Grain Production with Optical Sensing and Variable Rate Application

  1. William R. Raun *a,
  2. John B. Solieb,
  3. Gordon V. Johnsona,
  4. Marvin L. Stoneb,
  5. Robert W. Mullena,
  6. Kyle W. Freemana,
  7. Wade E. Thomasona and
  8. Erna V. Lukinaa
  1. a Dep. of Plant and Soil Sci., Oklahoma State Univ., Stillwater, OK 74078
    b Dep. of Biosyst. and Agric. Eng., Oklahoma State Univ., Stillwater, OK 74078

Abstract

In 2001, N fertilizer prices nearly doubled as a result of increased natural gas prices. This was further troubling when considering that the world N use efficiency (NUE) in cereal grain production averages only 33%. Methods to improve NUE in winter wheat (Triticum aestivum L.) have not included high spatial-resolution management based on sensed plant growth properties nor on midseason prediction of grain yield. Our objective was to determine the validity of using in-season estimates of grain yield (INSEY) and a response index (RI) to modulate N at 1-m2 spatial resolution. Four winter wheat field experiments were conducted that evaluated prescribed midseason N applications compared with uniform rates that simulated farmer practices. Our methods recognize that each 1-m2 area in wheat fields needs to be sensed and managed independently and that the need for fertilizer N is temporally dependent. Averaged over locations, NUE was improved by >15% when N fertilization was based on optically sensed INSEY, determined for each 1-m2 area, and a RI compared with traditional practices at uniform N rates.

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Copyright © 2002. American Society of AgronomyPublished in Agron. J.94:815–820.