Nitrogen Fertilizer and Irrigation Effects on Seed Yield and Oil in Camelina

Interest is growing in camelina (Camelina sativa L. Crantz) as a biofuel feedstock. However, there has been little camelina research in irrigated arid systems. A 2-yr field study in Maricopa, AZ, under an overhead sprinkler irrigation system determined the effects of 10 water levels (irrigation fraction 0.5–1.1) and five N fertilizer rates (38–150 kg N ha–1) on seed yield, seed oil content, and N use efficiency. Cultivar Robinson was planted in December 2012 and 2013. Nitrogen fertilizer (urea ammonium nitrate) was applied in three split applications. Irrigation amounts were from 125 to 380 mm, and in-season rain was 70 and 50 mm, in 2013 and 2014, respectively. Camelina seed yields were maximum at water level 7 (irrigation fraction 0.93) in 2013 at 1800 kg ha–1. Maximum seed yields were 1600 kg ha–1 at water level 6 (irrigation fraction 0.83) in 2014. These highest seed yields were achieved with 150 kg N ha–1 in both years. Oil content (maximum 41%) decreased with N rate but increased with water level. Seed N increased with N rate but decreased with irrigation level. Recovery efficiency of N fertilizer by camelina ranged from 12 to 72%. The results indicate that good high-oil camelina yields can be produced in the southwestern United States with 320 to 380 mm irrigation plus rain and N fertilizer rates of 150 kg N ha–1