Extreme drought reduces soil priming effect through improvement of carbon availability and reduction of stoichiometric imbalances

The data supporting the main findings of this study are publicly available at: http://datadryad.org/share/OW2fB4uKsB3W6RdklK6Znis73v03ToGFvV67EGcccv0

Soil organic carbon (C) represents the largest terrestrial C reservoir, but drought mediated shifts in root exudate-induced priming effects remain poorly understood. In this study, using soils from a 7-year field throughfall exclusion platform experiment, we conducted a controlled experiment by applying analogue root exudate (quantified through field observations) to soils under two moisture regimes: control (60% water holding capacity, WHC) and drought (35% WHC). Our results showed that soil priming effects decreased dramatically under drought relative to the control. Specifically, the priming effects over 30 days averaged 584 μg CO2 g-1 soil in the control, while drought reduced it by 44%. These changes in soil priming effect were primarily driven by C availability, nutrient stoichiometric imbalances, and microbial properties. Our findings highlight the importance of incorporating root exudate-microbial-nutrient feedbacks into biogeochemical models to better predict rhizosphere priming effects and soil C persistence under climate change.

This study was supported jointly by the National Natural Science Foundation of China (Grant No. 32271675, 32271713, 32241032, 32471683), and Heilongjiang Touyan Innovation Team Program (Forest Carbon Sink Assessment and Carbon Sequestration Management Innovation Team).

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