Hüseyin Barış Tecimen, Faculty of Forestry Soil Science and Ecology Dept., University of Istanbul, Istanbul, Turkey, Josef Gorres, University of Vermont, University of Vermont, Burlington, VT and Ryan Dustin Scott Melnichuk, Plant and Soil Science, University of Vermont, Burlington, VT
The A, E and B horizons of a spodosol soil under a mixed hardwood/softwood forest were used to construct mesocosm to observe the calcium-earthworm-plant interaction for Lumbricus rubellus (L), Amynthas agrestis (A) and a control treatment with no earthworms (N). However, for this study, aggregates were obtained from these treatments after 12 weeks incubation to measure soil Ca, pH, NO3--N, and NH4+-N as well as greenhouse emissions from each replicate aggregate set. The aggregates for each replicate had approximately 2-g mass. The aggregates were brought up to field capacity. Half the aggregates received NH4+-N additions (+), the others did not (-). Lower pH values in aggregates in earthworm soils than in the N(+) treatment (p(F) < 0.001) may have been caused by nitrification as NO3--N concentrations in the earthworm treatments were greater than in the N(-) treatment (p(F) < 0.032). Greater water soluble Ca concentrations in the earthworm treatments could not buffer the pH differences. N2O and CO2 emissions were consistently greater for the earthworm treatments in both NH4+-N treatments with the exception of A(+) which emitted significantly less N2O than either the L(+) or N(+). For CO2 in soils without NH4+-N additions, worm type and pH contributed significantly to CO2 predictions (p < 0.0001). For treatments with NH4+-N additions, model predictions (pH < 0.0096) were mainly influenced NH4+-N concentrations. For N2O without NH4+-N additions (p< 0.0001), earthworm type was the only significant contributor to predictions. For N2O emissions with NH4+-N additions (P< 0.0001), NH4+-N concentrations, NO3--N concentrations and earthworm type were significant contributors to the predictions.