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ARS Home » Pacific West Area » Maricopa, Arizona » U.S. Arid Land Agricultural Research Center » Water Management and Conservation Research » Research » Publications at this Location » Publication #321958
Title: Interactive effects of nitrogen fertilization and irrigation on grain yield, canopy temperature, and nitrogen use efficiency in overhead sprinkler-irrigated Durum Wheat

Author
item Mon, Jarai
item Bronson, Kevin
item Hunsaker, Douglas - Doug
item Thorp, Kelly
item White, Jeffrey
item French, Andrew
item Conley, Matthew

Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/11/2016
Publication Date: 3/8/2016
Citation: Mon, J., Bronson, K.F., Hunsaker, D.J., Thorp, K.R., White, J.W., French, A.N., Conley, M.M. 2016. Interactive effects of nitrogen fertilization and irrigation on grain yield, canopy temperature, and nitrogen use efficiency in overhead sprinkler-irrigated Durum Wheat. Field Crops Research. 191:54-65.

Interpretive Summary: Nitrogen and irrigation are the most important management areas in the production of high protein durum wheat in arid regions. Irrigation water availability, however, is decreasing and the cost of nitrogen (N) fertilizer is increasing. Therefore, there is a need to understand how irrigation interacts with N fertilizer management. A two-year field experiment was conducted in Maricopa, Arizona on a Casa Grande sandy loam soil to assess effects of N fertilizer and irrigation rates on grain yield, grain protein, canopy temperatures and N use efficiency. Five rates (0, 84, 168, 252, and 336 kg N ha-1) of N fertilizer as urea ammonium nitrate (32-0-0) were applied in three equal splits. Ten un-randomized, rates of irrigation ranging from deficit to excess of a base irrigation treatment were applied by varying the nozzles in a gradient in an overhead sprinkler system. Irrigation plus rain ranged from 230 to 660 mm in season one, and 180 to 600 mm in season two. Grain yield was highest in 2013 at the 252 kg N ha-1 fertilizer rate and at the (114 % irrigation). In 2014, grain yield was optimal at 220 kg N ha-1 at the 100% irrigation level. The maximum grain yield of 7500 kg ha-1 in 2013 was reduced to 5000 kg ha-1 in 2014 due to a warmer, shorter growing season. Recovery efficiency of added N fertilizer was high in this system (i.e. > 70 %) at N fertilizer and water levels that maximized grain yields. Grain Protein was maximum at lower water levels, was positively affected by N fertilizer rate. Yellow berry is a low protein, starchy condition, that was > 83 % present in the zero-N plots. Canopy temperatures decreased with increasing irrigation level, indicating no water stress. Nitrogen fertilizer applications also resulted in cooler canopy temperatures, but this effect was much less than the irrigation effect. In conclusion, irrigated durum wheat growers in arid regions would benefit the most, with the least risk of yield or protein reduction by applying 252 kg N ha-1 at the 1.0 base irrigation level.

Technical Abstract: Nitrogen and irrigation management are crucial in the production of high protein irrigated durum wheat (Triticum durum Desf.) in arid regions. However, as the availability of irrigation water decreases and potential costs and regulation of nitrogen (N) increase, there is a need to understand how irrigation interacts with N fertilizer management. A two-year field experiment was conducted in Maricopa, Arizona on a Casa Grande sandy loam to assess effects of N fertilizer and irrigation rates on grain yield, grain N, canopy temperatures and N use efficiency. Five rates of N fertilizer as urea ammonium nitrate (0, 84, 168, 252, and 336 kg N ha-1) were applied in three equal splits at Feekes 4, 7, and 9. Ten un-randomized, sequential rates of irrigation from 0.35 to 1.14 fraction of a non-deficit base irrigation treatment (maintained > 45 % soil water depletion) were applied by varying the nozzles in a gradient in an overhead sprinkler system. Irrigation plus rain ranged from 230 to 660 mm in season one, and 180 to 600 mm in season two. Grain yield was optimal in 2013 at the 252 kg N ha-1 fertilizer rate and at the 10th water level (1.14 irrigation), and between 168 kg and 252 kg N ha-1 at the 8th water level (1.0 irrigation) in 2014. The maximum grain yield of 7500 kg ha-1 in 2013 was reduced to 5000 kg ha-1 in 2014 due to a warmer, shorter growing season. Recovery efficiency of added N was high in this system (i.e. > 70 %) at N fertilizer and water levels that maximized biomass and grain yields. Grain N was maximum at a lower water level (level 3 or 0.50 - 0.54 irrigation), was positively affected by N fertilizer rate, and was negatively related to yellow berry incidence. Canopy/air temperature differences decreased linearly with increasing irrigation level. Nitrogen fertilizer applications reduced canopy temperature when water levels > 0.54 and 0.69 irrigation fraction in 2013, and 2014, respectively. This study results suggests that canopy temperature and weather data that reflects the grain-filling period could be used to improve irrigation and N management, respectively. In short, irrigated durum wheat growers on this soil would achieve the optimum grain yield, with the least risk of yield or protein reduction, by applying 252 kg N ha-1 at the 1.0 base irrigation level.