Carbon and nitrogen isotope measurements will be obtained from soil samples at various depths within mesocosms. These soil samples will be taken from bulk soil and earthworm burrows where applicable. Isotopic abundance measurements from soil samples of a known volume will be used to estimate the total amount of carbon and nitrogen within each mesocosm after inoculation with earthworms. Additionally, earthworms' effects on carbon and nitrogen distribution within the soil will be determined based on isotopic abundances within soil samples taken from earthworm burrows compared to those within soil samples taken from bulk soil.