Are the abundance of mid-size pores and soil carbon accrual via diverse plant communities occurred in highly sandy soil?

Abstract:

Soil organic carbon (SOC) is considered as an important indicator of soil quality and capability of nutrient supplies, and increasing SOC stock is also an acknowledged strategy for mitigating atmospheric carbon dioxide (CO₂). Planting bioenergy crops is recommended as one of the promising options to raise C stock in the soils, but the stock can increase with different rates by cropping systems. Diverse plant communities tend to form mid-size pores, and the raised volumes of microenvironments and soil matrix are expected to be beneficial for microbial functioning and has a role in receiving microbial products, respectively. Thus, higher soil C storage was reported, when pores in 30-150µm range were dominant. However, soil with large particles, such as sand, may not be able to exert the ability of diverse plant communities to form mid-size pores, thus having a negligible impact on potential C accumulation. Therefore, the objective of the research was to compare pore size distributions (PSD) and SOC contents between two types of soils, which had relatively low (52%) and high (87%) sand contents, 7 years after installations of monoculture switchgrass and restored prairie with 20 grass, legume, and forb species. The cores from two cropping systems in two sites having distinct sand contents were scanned by using micro-tomography (µCT), and the scanned images were analyzed to investigate PSD. Concentrations of SOC in loose soils surrounding cores were also measured.

Description about results of pore size distribution needs to be edited after analyses are done.

The numerically higher concentrations of SOC were observed in restored prairie system compared to switchgrass in soil from Lux Arbor, but the soil from Lake City had an opposite trend. In conclusion, in the highly sandy soil, restored prairie with plant diversity was less effective to form pores in mid-size range, and thus it couldn’t enhance capability of C sequestration.