Water Use and Evapotranspiration Coefficients for Camelina Sativa

The water use characteristics of Camelina sativa, an oilseed crop, were evaluated in an irrigation experiment in Maricopa, Arizona. Camelina (cv. Robinson) was grown between November 2006 and April 2007 in plots, each 10 by 17 m. Thirty-two of the field plots were replicated in a randomized block design consisting of irrigation treatments of four levels of soil water depletion: 40, 50, 65, and 75%. Six supplemental plots evaluated water stress at 85% soil water depletion. Weekly soil water content measurements were obtained over a soil profile of 1.9 m for all plots using neutron probes. In January 2007, following initial irrigations uniformly applied to all treatments, treatments received one to four additional surface irrigations. The camelina extracted soil water to a depth of 1.5 m. The seasonal evapotranspiration, calculated from soil water balance data, varied from 285 mm for the water stress plots to 371 mm for the 40% treatment. Excluding the water stress plots, seed yields for treatments varied from 950 to 1130 kg ha^–1, though differences were not significant. Mid-season camelina crop coefficients were on the order of 1.13 to 1.20. A camelina crop coefficient curve is presented as a function of days after planting.