Winter wheat fertilizer nitrogen use efficiency in grain and forage production systems |
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| Authors: | W E Thomason W R Raun G V Johnson |
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| Institution: | 1. Department of Plant and Soil Sciences , Oklahoma State University , 165 Agricultural Hall, Stillwater, OK, 74078;2. Department of Plant and Soil Sciences , Oklahoma State University , 165 Agricultural Hall, Stillwater, OK, 74078 E-mail: wrr@mail.pss.okstate.edu |
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| Abstract: | Abstract Nitrogen use efficiency (NUE) is known to be less than fifty percent in winter wheat grain production systems. This study was conducted to determine potential differences in NUE when winter wheat (Triticum aestivum L.) is grown strictly for forage or grain. The effects of different nitrogen rates on plant N concentrations at different growth stages and on grain yield were investigated in two existing long‐term winter wheat experiments near Stillwater (Experiment 222) and Lahoma (Experiment 502), OK. At both locations in all years, total N uptake was greater when wheat forage was harvested twice (Feekes 6 and flowering) compared to total N uptake when wheat was grown only for grain. Percent N content immediately following flowering was much lower compared to percent N in the forage harvested prior to flowering, indicating relatively large losses of N after flowering. Averaged over locations and years, at the 90 kg N ha?1 rate, wheat produced for forage had much higher NUE (82%) compared with grain production systems (30%). While gaseous N loss was not measured in this trial, the higher NUE values found in the forage production systems were attributed to harvesting prior to anthesis and the time when plant N losses are known to be greater. |
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