Decomposition in a peaty soil improved for pastoral agriculture

The rates of CO2 production and decomposition of C-13-enriched Lolium perenne leaves and roots in soil from the surface five cm of two upland stagnohumic gley soils were measured in laboratory experiments. One of the soils had been limed (pH 6.8) 13 years earlier. The other was unlimed (pH 3.7). Liming increased the rate of CO2 release from soil to which no L. perenne had been added. About 30% of the C-13 in L. perenne leaves remained in both limed and unlimed soil after 224 days. By contrast, less C-13 remained in the limed soil amended with L. perenne roots (44%) than in the limed soils (55%). Although the daily rate of CO2 from the plant material-amended soils was initially greater in the improved than in the unimproved soil, it subsequently declined more rapidly.