Tracking the Tango Between Tillage, Soil Health, and Weeds: Progress Report 2022

This BIOAg project evaluates how reintroducing tillage after long-term reduced disturbance affects soil health and weeds in western Washington. Two replicated field trials were established at the WSU Mount Vernon NWREC with four treatment replications and repeated over two years. Trial 1 compares continued no-till orchardgrass with a one-time spring tillage event followed by no-till, tracking changes in bulk density, penetration resistance, gravimetric water content, and field saturated hydraulic conductivity. Trial 2 compares two tillage implement systems (rototiller vs power harrow) in an annual rotation (kale in year 1, squash in year 2), measuring similar hydro-physical indicators. Soil biology was assessed using phospholipid fatty acid (PLFA) analysis for microbial biomass and community composition. Weed responses were measured using seedbank sampling (greenhouse grow-out and elutriation), in-season counts, biomass, and seed production estimates for common lambsquarters and shepherd’s purse.