A Data-Validated Stoichiometric Model for the Priming Effect.

Abstract

Due to global warming, interest in sequestering carbon by appropriately managing soils has contributed to studying the dynamic exchange of carbon and nitrogen in soils and atmospheric CO[Formula: see text]. The priming effect, or the intensified CO[Formula: see text] emissions from soil organic matter (SOM) decomposition in short periods by using labile substrates, has been a topic of interest over the last decades. A combination of two experimentally supported mechanisms explains the priming effect phenomenon, and for the first time, we combine them in a novel stoichiometric model. The model considers the effects of labile substrate utilization in soils during the SOM decomposition and how CO[Formula: see text] emissions rates are affected. Laboratory data and a local sensitivity analysis validate the accuracy and robustness of the model. We find an optimized ratio of labile carbon and nitrogen that intensifies SOM decomposition for different soil features. The priming effect is weakened as C/N in SOM increases for nutrient-poor soils and is independent of C/N in SOM for nutrient-rich soils. The time required for microorganisms to decompose SOM at its maximum rate is delayed only for labile carbon treatments and poor-nutrient soils but remains constant otherwise. Finally, the SOM degradation efficiency determines the priming effect's acceleration or reduction under different soil treatments.