Camelina: seed yield response to applied nitrogen and sulfur.

Camelina (Camelina sativa L Crantz) has received worldwide attention in recent years as a biofuel crop and as a broadleaf option in cereal-based cropping systems. The objective of our 3-year study was to determine camelina seed yield and nitrogen use efficiency (NUE) as affected by six applied nitrogen (N) rates at four rainfed sites in the Pacific Northwest (PNW) of the United States. An N + sulfur (S) variable was also included. Seed oil content as affected by applied N and S was also evaluated in 2010. The four sites and their average annual crop-year precipitation during the 3 years were Lind, WA (228 mm); Pendleton, OR (421 mm); Moscow/Pullman, ID (695 mm); and Corvallis, OR (1085). The majority of precipitation occurs in the winter and summers are comparatively dry. Camelina responded differently to applied N among sites based upon precipitation and available soil N. Seed yield did not respond to N rate treatments at Lind, presumably due to sufficient soil residual N and limited precipitation. Seed yield increased with applied N at Pendleton, Moscow/Pullman, and Corvallis. Optimum applied N rates ranged from 0 to 90 kg ha(-1) depending on annual precipitation and soil available N. Maximum seed yield increases attributable to applied N ranged from 19% at Pendleton to 93% at Moscow/Pullman. Camelina NUE was greatest at Moscow/Pullman although it decreased gradually with increasing applied N rates at all sites. Lind, Pendleton, and Corvallis had the same decrease in NUE of -0.06 kg seed for each additional kg of available N. Camelina did not respond to applied S at any site. Seed oil content was not affected by applied N or S. Based upon the results of this study, camelina requires about 12 kg N ha(-1) per 100 kg of expected seed yield. (C) 2013 Elsevier B.V. All rights reserved.