Plant roots are more important than temperature in modulating carbon release in a limed acidic soil

Lime is a common amendment to overcome soil acidity in agricultural production systems. However, plant root effects on lime and soil carbon (C) dynamics in acidic soils under varied temperature remain largely unknown. We monitored root effects of soybean on the fate of lime applied to an acidic soil at 20 and 30 degrees C in growth chambers. Soil respired CO2 was continuously trapped in columns without and with plants until the final stage of vegetative growth. Lime-derived CO2 was separated from total respired CO2 based on delta C-13 measurements in CO2. Leaching was induced at early and late vegetative growth stages, and the leachates were analysed for dissolved organic (DOC) and inorganic C (DIC) concentrations. Soil respiration significantly increased with lime addition at both temperatures (p < 0.001). The presence of soybean doubled the recovery of lime-derived CO2-C at 20 degrees C at the early growth stage; however, by the end of the experiment, the contribution of lime-derived CO2-C to soil respiration was negligible in all treatments, indicating that the contribution of lime to soil respiration was shortlived. In contrast, DIC and DOC concentrations in leachates remained elevated with liming and were greater in the presence of soybean. We observed no main temperature effects and no interactive effects of temperature and soybean presence on lime-derived CO2-C, DIC and DOC. These results highlight the role of plant-modulated processes in CO2 release and C leaching from lime in acidic soils, whereas an increase in temperature may be less important. Temperature and plant roots alter the rate of key processes controlling C dynamics in a limed acidic soil. Lime-derived CO2-C, DIC and DOC increased more in the presence of plants than with increased temperature. Root effects are more important than temperature for inorganic and organic carbon dynamics in limed acidic soils.