期刊
BIOGEOCHEMISTRY
卷 120, 期 1-3, 页码 37-49出版社
SPRINGER
DOI: 10.1007/s10533-014-9980-3
关键词
Soil organic carbon; Tallgrass prairie grassland; Deep-rooting perennial; Soil carbon turnover; Subsoil; Soil particle size fractionation
资金
- Land Institute's graduate research program
- Biotechnology and Biological Sciences Research Council [BBS/E/C/00005214] Funding Source: researchfish
- BBSRC [BBS/E/C/00005214] Funding Source: UKRI
The dynamics of roots and soil organic carbon (SOC) in deeper soil layers are amongst the least well understood components of the global C cycle, but essential if soil C is to be managed effectively. This study utilized a unique set of land-use pairings of harvested tallgrass prairie grasslands (C-4) and annual wheat croplands (C-3) that were under continuous management for 75 years to investigate and compare the storage, turnover and allocation of SOC in the two systems to 1 m depth. Cropland soils contained 25 % less SOC than grassland soils (115 and 153 Mg C ha(-1), respectively) to 1 m depth, and had lower SOC contents in all particle size fractions (2000-250, 250-53, 53-2 and < 2 mu m), which nominally correspond to SOC pools with different stability. Soil bulk delta C-13 values also indicated the significant turnover of grassland-derived SOC up to 80 cm depth in cropland soils in all fractions, including deeper (> 40 cm) layers and mineral-associated (< 53 mu m) SOC. Grassland soils had significantly more visible root biomass C than cropland soils (3.2 and 0.6 Mg ha(-1), respectively) and microbial biomass C (3.7 and 1.3 Mg ha(-1), respectively) up to 1 m depth. The outcomes of this study demonstrated that: (i) SOC pools that are perceived to be stable, i.e. subsoil and mineral-associated SOC, are affected by land-use change; and, (ii) managed perennial grasslands contained larger SOC stocks and exhibited much larger C allocations to root and microbial pools than annual croplands throughout the soil profile.
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