Submitted to: Irrigation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 12, 2012
Publication Date: September 1, 2013
Citation: Hunsaker, D.J., French, A.N., Thorp, K.R. 2013. Camelina water use and seed yield response to irrigation scheduling in an arid environment. Irrigation Science. 31(5):911-929. Interpretive Summary: Camelina sativa (camelina) is an oilseed crop that is currently being produced as a biofuel in northern U.S. regions. Camelina’s reputed drought tolerance and low nitrogen requirement make it an attractive potential crop for growers in the arid-west, where water availability for irrigation is limited. However, lack of information on camelina’s seed yield potential and irrigation management is a factor hindering its cultivation in the arid-west. Field experiments conducted in Arizona confirmed that the crop’s water requirement is low compared to the water use needs for traditional crops in the area, such as wheat. Results also indicated that camelina seed yields did not increase with frequency or amount of irrigation. Thus, camelina appears to be quite adaptable to seasonal fluctuations in irrigation water availability, which can be a factor in arid areas. Irrigation scheduling and nitrogen management information are provided to help growers of camelina with the management of the crop. This research suggests that camelina with its associated water-savings could create opportunities for growers in the arid-west with limited cropping alternatives. The paper will be of interest to growers, the biofuel industry, farm consultants, and government agencies.
Technical Abstract: Camelina sativa (L.) Crantz is a promising, biodiesel-producing oilseed that could potentially be implemented as a low-input alternative crop for production in the arid southwestern USA. However, little is known about camelina’s water use, irrigation management, and agronomic characteristics in this arid environment. Camelina experiments were conducted for two seasons (Jan. to May) in Maricopa, Arizona to evaluate the effectiveness of previously developed heat-unit and remote sensing basal crop coefficient (Kcb) models for predicting camelina crop evapotranspiration (ET) and irrigation scheduling. The experiments also evaluated the effects of two different irrigation scheduling frequencies and two levels of seasonal N applications on the final seed yield and oil content of camelina. A heat-unit based Kcb method was updated and validated during the second experiment to predict ET to within 12-13%. The remote sensing based Kcb method provided estimates of ET within 7-10%. Seed yield for treatments varied from about 1300-1750 kg ha-1 in both years, with yields above 2000 kg ha-1 for some individual plots. Seed oil contents were remarkably high, 45 to 54%. Under well-watered irrigation scheduling, maximum camelina seasonal water use (i.e., ET) was found to be no more than about 490 mm, revealing that camelina is a much lower water user compared with traditional crops grown at the same time in the area, such as spring wheat. Camelina ET was reduced when the soil water depletion reached about 60-65%, though seed yield reduction due to that level of soil water stress was minimal. However, the experiments confirmed earlier findings that seed yield will decrease rapidly when soil water depletion reaches about 70% and beyond. The experiments also suggest that for optimum yield a split application of N totaling about 100 kg N ha-1 is required. Further investigations are needed to characterize camelina yield response over a wider range of irrigation and N inputs, including testing of other varieties.