PS 20-7 - Response of Soil Nitrogen Cycling to Induced Drought

Abstract: Drought frequency and variable rainfall is predicted to become more severe over the coming years and has implications for causing detrimental effects on essential ecosystem services that are governed by soil fauna. Drought may heavily impact free-living nematode enrichment opportunists that are essential for nitrogen (N) cycling. This study aims to investigate the impact of drought on biological nitrogen cycling within two contrasting systems, a perennial polyculture and row-crop system. This study was conducted at the KBS-LTER (Hickory Corners, MI), where drought was induced on early successional and row-crop no-till systems. Soil samples (10 cm depth) were taken during pre and peak drought in no-till and early successional systems using a 1.05 cm diameter soil probe. Samples were then analyzed for soil protein and abundances of nematode enrichment opportunists (nematode families that respond rapidly to N input). Results indicated that soil protein was greater in irrigated early successional communities than compared to all drought and no-till systems (p< 0.05). In addition, nematode enrichment opportunist abundances were significantly greater in all irrigated systems when compared to drought systems (p< 0.05). Abundances of enrichment opportunists were also greater in no-till systems when compared to early successional systems (p< 0.05). These results indicate that drought has the potential to cause detrimental effects on nematode enrichment opportunists and have implications for N cycling. Systems with greater perennial diversity have the potential to increase the resiliency of biological N cycling under drought conditions.