A novel technique for rapidly separating willow roots from clay soil

Non-Peer Reviewed ; Numerous studies have examined the root dynamics of willow biomass energy crops growing on medium to coarse-textured soils, using either soil coring, minirhizotron techniques, or a combination thereof. However, neither approach is well suited for studying roots in soil of high clay content. Our objective was to test the efficacy of using a simple baking soda (NaHCO3) pre-treatment for facilitating the separation of willow roots from a Vertisol (70% clay). Soil cores were collected from within a willow variety trial plot of Tully Champion (Salix viminalis x S. miyabeana) and were either conventionally washed (i.e., no pre-treatment) or washed following a pre-treatment consisting of shaking the sample for 15 min with either deionized water or 1.2M NaHCO3. Measurement variables included washing duration, water usage, and recovery of fine (< 2 mm) and coarse roots. The ranking of washing duration and water usage was 1.2M NaHCO3 pre-treatment < deionized water pre-treatment < conventional washing. Compared to conventional washing, the 1.2M NaHCO3 pre-treatment reduced the washing duration and water usage by 45 and 61%, respectively, while increasing the fine-root recovery by 29%. There was no significant difference (P > 0.05) in coarse root recovery among the three washing methods. Developing a quicker technique of separating willow roots from high clay content soils hould promote further investigations of root growth dynamics within this traditionally difficult soil type.