Long-term field experiment for monitoring soil carbon content in Japanese grasslands: initial data from 2010 to 2012

摘要

A long-term field experiment for monitoring soil carbon content in Japanese grasslands started in 2010 to investigate the changes in soil carbon content and the effect of composted livestock manure application. We established grassland plots with 3 levels of manure application treatment at 10 sites. Bulk density values in many sites had wide inter-replicate and inter-annual variability. It is reasonable to suppose that the variability in the bulk density reflect spatial variability of physical properties within the grasslands because the annual trends of the bulk density values were not consistent. Organic carbon concentration tended to increase yearly in the surface layer (0-5 cm), whereas those for the subsoil layer (5-30 cm) stayed relatively constant. The organic carbon concentration in the surface layer tended to increase with increasing latitude and the amount of manure applied. When data from all the sites were taken into account, carbon content also tended to increase over time following grassland renovation. These results indicate that Japanese grasslands have the potential to sequester organic carbon. The monitoring has just begun, and it is important to continue the effort to achieve the goals of this study.