Greenhouse Gas Emissions From Aggregates of a Mesocosm Soil Worked By Lumbricus Rubellus and Amynthas Agrestis.

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, NO_3^--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 NO_3^--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, NO_3^--N concentrations and earthworm type were significant contributors to the predictions.