Camelina growth and yield response to sowing depth and rate in the northern Corn Belt USA

Camelina (Camelina sativa L.) is gaining interest as a productive alternative oilseed crop for biofuels, bioproducts, and healthy food-use applications. Developing sound agronomic practices for its production is key to optimizing its seed oil yield potential. Plant stand establishment of camelina has been problematic in some environments, which may be related to its small seed size and current recommendation for shallow sowing. Shallow sowing can diminish seed to soil contact and expose seeds to large soil temperature and moisture fluctuations, which greatly affect germination and seedling emergence. A study was conducted in 2011 and 2012 on a Barnes loam soil in western Minnesota to examine the effects of sowing spring camelina at soil depths of 1, 2, and 4 cm at sowing rates of 2, 3, and 6 kg ha−1. Seedling emergence increased with sowing rate, but averaged across depths it had no effect on seed yield. Seedling emergence between the 1 and 2 cm sowing depths did not differ in 2012, while stands were reduced by an average of 29% at the 2 cm depth in 2011, but seed yields did not differ between the two sowing depths in either year. However, averaged across sowing rates, sowing at 4 cm led to a 64% stand reduction and a significant 22% loss of yield compared with the 1 and 2 cm depths. Neither sowing depth nor rate affected seed oil content or harvest index. Results show that camelina has exceptional yield compensation capacity at low plant densities and can be sown deeper than commonly recommended (i.e., ≤1.0 cm) without compromising yield in the northern Corn Belt. Sowing to a depth of 2 cm may be beneficial for certain soils prone to large temperature and moisture fluctuations.