The priming effect is well acknowledged in soil systems but the effect of nitrogen(N)fertilization remains elusive.To explore how N modifies the priming effect in soil organic matter(SOM),one in situ experiment with 1...The priming effect is well acknowledged in soil systems but the effect of nitrogen(N)fertilization remains elusive.To explore how N modifies the priming effect in soil organic matter(SOM),one in situ experiment with 13C labeled glucose addition(0.4 mg C g^–1 soil,3.4 atom %^13C)was conducted on soil plots fertilized with three gradients of urea(0,4 and 16 g N m^–2 yr^–1).After glucose addition,the soil CO2 concentration and phospholipid fatty acid(PLFA)were measured on day 3,7,21 and 35.The study found that N fertilization decreased soil CO2,PLFA and the fungi to bacteria ratio.Glucose triggered the strongest positive priming in soil at 0 g N m^–2 yr^–2,meanwhile N fertilization decreased SOM-derived CO2.Soil at 4 g N m^–2 yr^–2 released the largest amount of glucose-derived carbon(C),likely due to favorable nutrient stoichiometry between C and N.Stable microbial community biomass and composition during early sampling suggests"apparent priming"in this grassland.This study concludes that N fertilization inhibited soil priming in semi-arid grassland,and shifted microbial utilization of C substrate from SOM to added labile C.Diverse microbial functions might be playing a crucial role in soil priming and requires attention in future N fertilization studies.展开更多
基金National Natural Science Foundation of China(31770519)National Key Research and Development Program of China(2017YFC0503805)
文摘The priming effect is well acknowledged in soil systems but the effect of nitrogen(N)fertilization remains elusive.To explore how N modifies the priming effect in soil organic matter(SOM),one in situ experiment with 13C labeled glucose addition(0.4 mg C g^–1 soil,3.4 atom %^13C)was conducted on soil plots fertilized with three gradients of urea(0,4 and 16 g N m^–2 yr^–1).After glucose addition,the soil CO2 concentration and phospholipid fatty acid(PLFA)were measured on day 3,7,21 and 35.The study found that N fertilization decreased soil CO2,PLFA and the fungi to bacteria ratio.Glucose triggered the strongest positive priming in soil at 0 g N m^–2 yr^–2,meanwhile N fertilization decreased SOM-derived CO2.Soil at 4 g N m^–2 yr^–2 released the largest amount of glucose-derived carbon(C),likely due to favorable nutrient stoichiometry between C and N.Stable microbial community biomass and composition during early sampling suggests"apparent priming"in this grassland.This study concludes that N fertilization inhibited soil priming in semi-arid grassland,and shifted microbial utilization of C substrate from SOM to added labile C.Diverse microbial functions might be playing a crucial role in soil priming and requires attention in future N fertilization studies.
