Soil water limitation intensity alters nitrogen cycling at the plant-soil interface in Scots pine mesocosms.

Background and aim: More intense episodes of drought are expected to affect terrestrial nitrogen (N) cycling by altering N transformation rates, the functioning of soil microorganisms, and plant N uptake. However, there is limited empirical evidence of how progressive water loss affects N cycling at the plant-soil interface. Methods: We adopted Results: With increasing water limitation, the release of N from decomposing litter into the soil declined rapidly. However, moderate levels of water limitation barely affected the microbial metagenome associated with N cycling and the uptake of N by the saplings. Comparatively, severe levels of water limitation impaired plant N uptake, and increased the prevalence of microbial N-cycling genes potentially involved in mechanisms that protect against water stress. Genes associated with the uptake and release of N during mineralization and nitrification declined under low soil water contents. Conclusions: When soil water becomes largely unavailable, the cycling of N at the plant-soil interface is slowed down, and microbial and plant tolerance mechanisms may prevail over N uptake and microbial decomposition. Supplementary Information: The online version contains supplementary material available at 10.1007/s11104-025-07758-z.