Wheat and Barley Growth and N Fertilizer Utilization Under Sprinkler Irrigation1

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AbstractInformation on the effectiveness of N fertilizer applied through sprinkler irrigation systems for springsown wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) is limited. Objectives were to determine grain yield and quality responses and N‐use efficiency when N fertilizer was applied at irrigation to wheat and barley grown on a fine‐silty, mixed Typic Haploboroll. Nitrogen fertilizer was applied to sprinkler irrigated ‘Newana’ hard red spring wheat and ‘Shabet’ malting barley at seeding or split between seeding and heading, flowering, or watery kernel growth stages. Treatments included N rates of 0, 50, 100, and 150 kg N/ha at seediig, 75 kg N/ha at seeding plus 25 kg N/ha at heading or flowering, and 50 kg N/ha at seeding plus 50 kg N/ha at heading or 25 kg N/ha at heading and 25 kg N/ha at flowering. Additionally, 25, 50, and 25 kg N/ha were applied to barley at seeding, heading, and flowering, respectively; and 100 and 25 kg N/ha were applied to wheat at seeding and watery kernel stage, respectively. Nitrogen at seeding was broadcast as NH4No3‐, Subsequent N applications were broadcast as NH4NO3, several, hours prior to an irrigation to simulate application through the sprinkler system. Wheat plots contained subplots fertilized with 15NH415NO3 containing 1.31 atom percent 15N to determine the fate and utilization efficiency of applied N. Grain yield increased from 1,100 to 4,850 and from 1,240 to 4,570 kg/ha for wheat and barley, respectively, as N rates were increased from 0 to 150 kg N/ha at seeding. When 100 kg N/ha was split between seeding and at irrigation, wheat yields decreased from 3,890 to 3,540 and 2,975 kg/ha as the amount of N applied at seeding was decreased from 100 to 75 and 50 kg N/ha, respectively. Barley yields averaged 4,130 kg/ha for treatments totaling 100 kg N/ha and were generally not affected by shifting N applications from seeding to at irrigation. Differential response to split applications of N was related to differences in number of spikes per unit area at harvest. The number of spikes/m2 decreased for wheat and increased for barley as the proportion of the N fertilizer applied at seeding decreased. Nitrogen fertilizer recovery in the straw and grain of wheat plants at harvest was 52.5 and 50.8% where 100 kg N/ha was applied at seeding or split between seediig and at irrigation, respectively. Percentage recovery of N fertilizer was lower in straw and higher in grain when N was applied at imgation as compared to seeding time application. Failure to obtain positive grain yield responses or increases in overall N fertilizer efficiency indicate no advantage to splitting N fertilizer applications between seeding and Irrigation for spring seeded wheat and barley on deep, medium‐fine textured soils