Leaching of Dissolved Organic Carbon (DOC) as Affected by Plant Residue Composition and Soil pH

摘要

Leaching column experiment was conducted in the laboratory to investigate the influence of soil pH and plant residue incorporation on dissolved organic carbon (DOC) output.The results indicated that the pH in leachate was greatly increased when plant residues were incorporated into soils with very low pH (pH 3.0 and pH 3.5),but it was not the case in the soil with pH 6.5.At the end of leaching experiment,cumulative DOC output ranged from 260 to 457 mg C· kg-1 soil in the control columns,and the highest amount was found in the soil with pH 6.5.Plant residue incorporation significantly increased cumulative DOC output by 471 to 948 mg C· kg-l soil at rice straw treatment and by 2,268 to 4,068 mg C· kg-1 soil at Chinese milk vetch (CMV) treatment as compared to the corresponding control.Our results suggest that soil pH and the composition of plant residues are the key factors for determining DOC output during plant residue decomposition.