Increased plant nitrogen loss with increasing nitrogen applied in winter wheat observed with 15nitrogen |
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| Authors: | H L Lees W R Raun G V Johnson |
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| Institution: | 1. Department of Plant and Soil Sciences , Oklahoma State University , Stillwater, OK, 74078–0507;2. Department of Plant and Soil Sciences , Oklahoma State University , Stillwater, OK, 74078–0507 E-mail: wrr@agr.okstate.edu. |
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| Abstract: | Nitrogen (N) fertilizer is generally the most costly input for winter wheat (Triticum aestivum L.) production. Therefore, it was important to maximize fertilizer use efficiency and minimize N losses to the environment. One of the mechanisms responsible for decreased N use efficiency (NUE) was plant N loss. The objectives of this experiment were to determine fertilizer N recovery in winter wheat when produced for forage and grain, and to quantify potential plant N losses from flowering to maturity in winter wheat. Two long‐term (>25 years) winter wheat (Triticum aestivum L.) N rate fertility experiments (Experiment 222 and Experiment 502) were selected to evaluate 15N fertilizer recovery. Percent 15N recovery was determined from all microplots in plant tissue at flowering, in the grain, and straw at harvest and in the soil. Fertilizer N(15NH4 15NO3) was applied atratesof 0, 45, 90, and 135kg N ha‐1 in Experiment 222, and 0, 22, 45, 67, 90, and 112 kg N ha‐1 in Experiment 502. The ratio ofNO3 ‐to NH4 + in wheat forage at flowering was positively correlated with estimated plant N loss. Estimated plant N loss (total N uptake in wheat at flowering minus N uptake in the grain and straw at maturity) ranged from a net gain of 12 kg N ha‐1 to a loss of 42 kg N ha‐1, and losses increased with increasing N applied. |
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| Keywords: | Cunoniaceae New Caledonia macronutrient micronutrient plant physiology serpentine Ni |
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