Nutrient, Metal and Mineral Availability in Vermont Sugarbush Soil in the Presence and Absence of Earthworms.

Much of the Northeastern United States was devoid of native earthworms due to extinction caused by the Wisconsian glaciation.  Since their introduction by European explorers, bioturbation by earthworms has resulted in soil modifications and changes in nutrient cycling.  Beginning June of 2009, an organic sugarbush plantation near Cabot, Vermont, was surveyed for areas with and without earthworms.  Five plots each were established at sites without earthworms (NE) and with earthworms (E).  To investigate the effect of duff layer loss in the absence of worms, a third set of five plots without earthworms was stripped of its duff layer (NE/ND).  Plant Root Simulator (PRS®) probes from Western Ag Innovations were randomly placed in the plots in the top mineral horizon, where they adsorbed macronutrients (N, P, K) and select metals (Ca, Mg, Fe, Mn, Cu, S, Pb, Al, Cd) for 14 or 21 days.  Probes were analyzed for sorbed ions by Western Ag Innovations.  Available nutrients/metals were statistically significant (ANOVA) among plot types within the same sample dates and within plots types at different sample dates at a p-value of 0.05.  While total inorganic nitrogen (NO3 + NH4) was not different, significantly greater amounts of NO3 were available in earthworm plots. Available Ca was greater and K was less in earthworm plots than in plots without earthworms regardless of the presence/absence of the duff layer.  Pattern of inorganic nitrogen availability differed between earthworm and no earthworm plots during the growing season.