Dataset for Experimental Variation in Maximum Soil Depth Controls Near-Surface Carbon and Nitrogen Cycling

Soil depth to bedrock or impermeable layer can vary greatly, contributing to landscape heterogeneity that may yield strong control on near-surface soil biogeochemical processes. We experimentally manipulate soil depth (i.e. control volume), water inputs, and plant functional type, and quantified the response of soil carbon (C) and nitrogen (N) dynamics in soils 0-10 cm deep for a cold desert ecosystem. Soil moisture was consistently greater in 0.5 m vs. 2 m control volumes. However, the coefficient of variation for soil moisture pools trended significantly higher with less effective precipitation in 0.5 m control volumes, whereas 2 m profile soil moisture pools remained relatively constant and well buffered. Net N mineralization was 1.24× greater in 0.5 vs. 2 m control volumes during dry conditions but decreased in a cold wet year. Net N mineralization also varied between native shrub-steppe vs. exotic bunchgrass during the wet spring. Net nitrification rates were 4.8× greater in 0.5 vs. 2 m control volumes and were positively correlated with surface soil moisture content. Mean profile δ13C values were significantly more enriched (0.8‰) in 2 vs. 0.5 m control volumes, reflecting greater plant-water limitation. Mean profile δ15N values were 0.8‰ more enriched in 0.5 vs. 2 m control volumes, indicating enhanced pathways of N cycling and loss. Total C and N pools were 1.56× and 1.23× greater, respectively, in 0.5 vs. 2 m control volumes