The Washington State Oilseed Cropping Systems Research and Extension Project (WOCS) is funded by the Washington State Legislature to meet expanding biofuel, food, and feed demands with diversified rotations in wheat based cropping systems. The WOCS fact sheet series provides practical oilseed production information based on research findings in eastern Washington. More information can be found at: http://css.wsu.edu/biofuels/.
Funding and support for the WOCS provided by:
Washington State Legislature, Washington State Department of Agriculture, Washington Department of Commerce, and the Washington State University Energy Program.
The wheat-dominated inland Pacific Northwest (iPNW) has a broad range of environments and soil types; however, the region lacks crop diversity. Many other semi-arid wheat-growing regions throughout the world have successfully included oilseeds in their rotations for decades (Conley et al. 2004; Kirkegaard et al. 2008; Zentner et al. 2002). While interest in oilseed crops in the iPNW dates back to the 1970s (Divine et al. 1977) production has lagged due to socioeconomics, unique environmental conditions, and agronomic reasons (Pan et al. 2016a).
Growers in the iPNW have fine-tuned their agronomic management practices to meet the needs of wheat production for more than a century. Agronomic approaches to oilseed production require adjustments to account for physiological differences between the two types of crops. By coordinating production practices with growth stages and growing conditions, the impacts of moisture and temperature stress can
Oilseeds are recognized as potential rotational crops due to their ability to extract deep soil moisture in water-limited environments more effectively than wheat or peas (Merrill et al. 2004). Opportunities for integrating oilseeds into traditional cropping sequences in the iPNW include (1) substituting spring canola or camelina for either spring wheat or legumes in high rainfall areas (>18”), (2) planting winter or spring oilseeds instead of winter or spring wheat in the intermediate rainfall zone (12–18”), and (3) replacing winter wheat with winter canola every fourth year in the low rainfall zone (<12”).
Crop management is typically tailored to the physiological and morphological traits of each crop. Farm equipment, timing of farm operations, and agrichemical management are also designed in consideration of these traits. While canola producers can take advantage of wheat-based farm machinery and equipment, farm operations need to be tailored specifically to canola physiology and morphology to optimize yield and quality. A review of these differences between crops from planting to harvest, in the context of iPNW environmental stressors, provides insight into recommended modifications of wheat management strategies for canola production.
Wheat has a much larger seed size compared to canola and camelina (Figure 1; Vollmann et al. 1996) resulting in a lower number of seeds per pound and ultimately a higher seeding rate (lb/acre; Table 1). Seed size is affected by both variety and seed production environment (Lamb and Johnson 2004). When deciding on a seeding rate, both seed size and number of seeds per pound become an important factor when targeting specific population goals. Seven to fourteen plants per square foot are recommended to meet yield goals of spring canola (Canada Council) and 4–15 plants per square foot for winter canola (Boyles et al. 2009). In comparison, optimum spring wheat populations range from 30–32 plants per square foot, and