Introducing canola as an alternative crop in the PNW
Silicon (Si) levels have a wide range of variation in plant and soil systems depending on abiotic and biotic factors. In the inland Pacific Northwest the predominant cropping system relies on wheat (a Si accumulator). Within this region, studies have shown high levels of total soil Si and evidence of Si compounds becoming potential cementing agents therefore degrading soil quality. The dependence of Si cycling on plant type, environmental factors, and agronomic inputs needs to be assessed in order to determine if introduction of canola (a non-accumulator of Si) could enhance soil quality by reducing the occurrence or severity of soil crusting in comparison to wheat-dominated systems. Both wheat and canola were grown in a greenhouse and upon harvest the wheat residue accumulated between 40–65% more Si than canola. This residue was then used in a laboratory incubation with soil pH as a variable. The results suggest that a higher pH, rather than residue type, was the primary factor positively affecting surface resistance, water soluble Si (Siws), and amorphous Si (Siam). The greenhouse residues were also used in a decomposition study, which showed wheat had a slightly faster decomposition rate compared to canola, consistent with the lower starting C:N ratio of the wheat residue. An additional incubation with applications of amorphous silica (SiO2) confirmed that such v applications positively influence water loss, soil Si, surface resistance, and crust thickness. In addition to the silica treatments, soils from two cropping systems were used: one previously cropped in wheat and the other in canola. The soil previously cropped in wheat had higher soil Siam, surface resistance, and crust thickness compared to the canola system demonstrating the influence crop rotation can have on Si related soil properties. A field survey of Siws, Siam, and surface resistance showed little dependence across cropping systems. As shown from the experiments under controlled conditions, it can be concluded that Si cycling does affect important soil physical properties. The lack of confirmation in the field survey suggests that other factors influence the state of Si in active cropping systems and should be the focus of further research.
As a child my family moved around a lot, but I consider myself to be from Parker, CO. Prior to college, I spent four years training with the USA Rifle Team at the Olympic Training Center in Colorado Springs, CO. Throughout those four years I competed on a national and international level. In 2007, I was recruited to the University of Alaska Fairbanks to become a member of their rifle team. During my time in Alaska, I was fortunate to be apart of multiple athletic and academic achievements including a national championship title and student of the year. This is when my love for soil science and ambitions for graduate school began. In 2011, I graduated with a B.S. in Natural Resource Management with a concentration in Agriculture at High Latitudes. Later that year I was enrolled at WSU as a graduate student under advisement by William L. Pan and funded through the REACCH project. After two and a half years I received a M.S. in Soil Science. As a graduate I have been employed at WSU as an Associate in Research aiding in research associated with REACCH and publishing extension material.
Publications and Presentations:
Beard, T., K. Sowers, and W. Pan. 2017. Physiology matters: adjusting wheat-based management strategies for oilseed production (Oilseed Series). WSU Extension publication FS244E.
Pan, W., M. Reese, T. Beard, I. Madsen, and T. Maaz. 2016. Subsoil Quality: Do our subsoils provide wheat and canola roots with ample water and nutrients during grain filling? In 2016 Dryland Field Day Abstracts: Highlights of Research Progress. Dept. of Crop and Soil Sciences Tech Report 16-1, WSU, Pullman, WA.