Organic N deposition favours soil C sequestration by decreasing priming effect

Background and aims: Atmospheric nitrogen (N) deposition alters the priming effect (PE), which is defined as the change in native soil organic carbon (SOC) decomposition by exogenous C inputs. However, how the priming intensity varies under chemically heterogeneous N deposition, particularly with increasing labile C input, remains unclear. Methods: We collected soils from a temperate forest in northeastern China that had received simulated organic and/or inorganic N deposition for 6 years. The soils were incubated with or without three levels of 13C-labelled glucose solution for 152 days. CO2 emission and its 13C value were continuously measured to calculate the PE. Results: Enhanced SOC decomposition (i.e., a positive PE) was observed after glucose addition, regardless of the N deposition form. The PE intensity increased with the increase in the glucose addition level. However, organic N decreased the PE by 12.3-23.2%. The SOC-derived microbial biomass was 16.2-34.3% lower in organic N-treated soil, indicating that preferential utilization of exogenous labile C by microorganisms was responsible for the decrease in PE. The PE inhibition by organic N increased nonlinearly as a function of glucose level. Furthermore, the net annual change in SOC as a balance between the replenishment of added glucose-C and primed C was larger in organic N-treated soil due to a decrease in soil microbial metabolic quotient. Conclusions: In this study, we found that organic N deposition inhibited the PE, and the inhibition effect was intensified with increasing C inputs, favouring SOC sequestration. © 2019, Springer Nature Switzerland AG.

Tian P.1, 2 , Liu S.1, 2 , Wang Q.1, 3 , Sun T.1 , Blagodatskaya E. 4, 5
Springer International Publishing
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  • 1 Huitong Experimental Station of Forest Ecology, CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Shenyang, 110164, China
  • 2 University of Chinese Academy of Sciences, Beijing, 100049, China
  • 3 Huitong National Research Station of Forest Ecosystem, Huitong, 418307, China
  • 4 Department of Soil Ecology, Helmholtz Centre for Environmental Research – UFZ, Saale, Halle, Germany
  • 5 Peoples Friendship University of Russia (RUDN University), Moscow, 117198, Russian Federation
C addition level; C sequestration; N deposition form; Organic N; Preferential utilization; Priming effect
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