Author :  
Xiaolin Dou, Xiaoli Cheng, Ping He, Ping Zhu, Wei Zhou, Ligang Wang

Year : 

Title : 
Dynamics of physically- separated soil organic carbon pools assessed from
δ13C changes under 25 years of cropping systems

Journal : 
Soil & Tillage Research


They combined soil fractionation with C isotope analyses to investigate the SOC dynamics of the various soil fractions in a black soil of Northeast China after 25 years of tillage.

Soil samples from the initial condition (CK) and 2 cropping treatments including continuous
maize cropping (MM), maize–soybean rotation (MS) were separated into 4 aggregate sizes (< 53 μm,

250–53 μm, 2000–250 μm, and >2000 μm).

The MS system was more beneficial for the SOC accumulation in macroaggregates (> 250 μm) than the MM system because of enhanced SOC in heavier fractions (iPOM and mSOM); this was probably induced by the differentiation of the belowground humification rate between soybean and maize roots, while the MM system may be a more effective measure for future soil C sequestration because most of the stable C is stored in the small size fraction (< 53 μm).

The δ13C values indicated that, among aggregate sizes, the fastest soil C turnover occurred in microaggregates (250–53 μm). Moreover, C in the MS soils had a faster turnover rate than in the MM soils.


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