Soil organic carbon priming co-regulated by labile carbon input level and long-term fertilization history
SCIENCE OF THE TOTAL ENVIRONMENT(2023)
摘要
Labile carbon (C) input and fertilization have important consequences for soil organic matter (SOM) decomposition via the priming effect (PE), thereby impacting soil fertility and C sequestration. However, it remains largely uncertain on how the labile C input levels interact with long-term fertilization history to control PE intensity. To clarify this question, soil samples were collected from a 38-year fertilization field experiment (including five treatments: chemical nitrogen fertilizer, N; chemical fertilizer, NPK; manure, M-1; 200 % manure, M-2; NPK plus M-2, NPKM2), with strongly altered soil physiochemical properties (i.e., soil aggregation, organic C and nutrient availability). These soil samples were incubated with three input levels of C-13-glucose (without glucose, control; low, 0.4 % SOC; high, 2.0 % SOC) to clarify the underlying mechanisms of PE. Results showed that the PE significantly increased with glucose input levels, with values increasing from negative or weak (-2.21 to 3.55 mg C g(-1) SOC) at low input level to strongly positive (5.62 to 8.57 mg C g(-1) SOC) at high input level across fertilization treatments. The increased PE intensity occurred along with decreased dissolved total nitrogen (DTN) contents and increased ratios of dissolved organic C to DTN, implying that the decline in N availability largely increased PE via enhanced microbial N mining from SOM. Compared to N and NPK treatments, the PE was significantly lower in the manure-amendment treatments, especially for low input level, due to more stable SOM by aggregate protection and higher N and phosphorus availability. These results suggested that manure application could alleviate SOM priming via increased soil C stability and nutrient availability. Collectively, our findings emphasize the importance of long-term fertilization-driven changes in labile C inputs, SOM stability, and nutrient availability in regulating PE and soil C dynamics. This knowledge advances our understanding of the long-term fertilization management for soil C sequestration.
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关键词
Priming effect,Long-term fertilization,Carbon input level,Aggregate distribution,Nutrient availability
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