Project Summaries

11-860OK  Project Manager: E. M. Barnes


Brian Arnall, Oklahoma State University

Nitrogen (N) fertilization has been based on yield goals and historic production levels. It has consistently been shown that this method of N rate recommendation can result in poor N use efficiency and consequently lowered economical returns. Researchers initiated the use of optical sensors in cereal crops to determine mid-season N-rates since the late 90s. Since then the technology has made great advances and the Sensor Based Nitrogen Rate Calculator (SBNRC) developed by Oklahoma State University annually shows increased profits of $10-15 an acre in winter wheat as fertilizer N savings or increased yield. It has been well documented with data from Oklahoma State Soil Fertility long term trials that the optimum nitrogen rate for winter wheat production ranges significantly from one year to the next. While the optimum N rate for cotton production may not deviate from the average as often as wheat, there was still opportunity to increase yields or decrease inputs in four of the last ten years.

For the last four years, the initial research has been implemented to develop a SBNRC for Oklahoma cotton production. To date, the three integral portions of the SBNRC have been explored. Yield prediction models that use sensor readings collected mid-season to determine final lint yields have been developed for production in systems in both southwest and north central Oklahoma. The relationship between nitrogen response measured by the sensor mid-season and final yields has been established. In 2012, a study was planted to document whether the cotton plant can undergo N stress prior to mid-season fertilization and still reach maximum yields. In addition, this trial was intended to also help identify the optimal growth stage for sensing. The next logical step is the test the SBNRC at multiple growth stages and under a range of preplant N rates. A trial was planted to implement the SBNRC nutrient management strategy to determine if the SBNRC can predict the correct side-dress N rate and if use of sensor technology improves the profitability of current N management practices.

While these studies were planted in 2012, both locations were lost to drought and lack of irritation. Surface water for both irrigation sources was less than 17% capacity and no water was available for irrigation. Plans are in place to attempt this project again in 2013.


Project Year: 2012

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