Disentangling the effect of nitrogen supply on the priming of soil organic matter: A critical review
Yunyun Zheng, Jian Jin, Xiaojuan Wang, Peter M. Kopittke, James B. O’Sullivan, Caixian Tang
Abstract
The addition of fresh substrates can alter the decomposition of the native soil organic matter, referred to as the priming effect (PE).It is a crucial process within the cycling of soil organic carbon (C) and believed to be regulated by nitrogen (N) input.However, the direction and magnitude of this N effect on the PE are complex due to the involvement of various factors following N addition into the soil.This review synthesizes the key factors driving the responses of the PE to N addition from the perspective of C-substrate quantity and quality, N addition rates and forms, soil properties including organic C stability, N availability, electrical conductivity, pH and pH buffer capacity.The temporal change in the N effect on the PE is also discussed.In studies observing a suppressive effect of N addition on the PE, the role of N addition in directly suppressing microbial community metabolism (e.g., osmotic stress and low pH) has been largely ignored.We propose the application of multi-omics techniques to examine the relationship between microbial functional traits and soil C cycling through the PE and its response to N addition, as well as the application of spatial omics and imaging techniques in exploring the connection between in-situ soil C distribution and the PE and its response to N addition.Such studies can potentially elucidate how elevated atmospheric CO 2 may affect the PE and thus soil C stock via increasing plant C input and regulating nutrients sources for plant uptake under N inputs.