59 / 2024-08-01 11:49:40

中度酸化促进土壤氧化亚氮排放

Global potent greenhouse gas nitrous oxide (N2O) emissions from soil are

accelerating, with increases in the proportion of reactive nitrogen emitted as

N2O, i.e., N2O emission factor (EF). Yet, the primary controls and underlying

mechanisms of EFs remain unresolved. Based on two independent but complementary

global syntheses, and three field studies determining effects of

acidity on N2O EFs and soil denitrifying microorganisms, we show that soil pH

predominantly controls N2O EFs and emissions by affecting the denitrifier

community composition. Analysis of 5438 paired data points of N2O emission

fluxes revealed a hump-shaped relationship between soil pH and EFs, with the

highest EFs occurring in moderately acidic soils that favored N2O-producing

over N2O-consuming microorganisms, and induced high N2O emissions. Our

results illustrate that soil pH has a unimodal relationship with soil denitrifiers

and EFs, and the net N2O emission depends on both the N2O/(N2O+N2) ratio

and overall denitrification rate. These findings can inform strategies to predict

and mitigate soil N2O emissions under future nitrogen input scenarios.