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 uplan d stagnohumic gley soils were measured in laboratory experiments. One of the soils had been limed (pH 6.8) 13 years earlier. The other was u nlimed (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. peren ne leaves remained in both limed and unlimed soil after 224 days. By c ontrast, 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 r apidly.