Lime-induced loss of soil organic carbon and effect on aggregate stability

We investigated the decline in soil organic C on an Oxic Paleustalf (red earth) as a result of lime application (1.5 t CaCO3 ha(-1)) in New South Wales, Australia and determined how loss of organic C was related to soil aggregate stability changes. Organic C lost as a result of liming was mainly (up to 84% of total loss) in the form of light fraction (specific gravity <1.8) bound to macroaggregates. With liming, a given level of aggregate stability was achieved at a lower soil organic C level in limed soil (e.g., total C level for a 50% aggregate stability was 13.0 and 17.8 g kg(-1) for limed and unlimed soils, respectively). Increased aggregate stability in limed soils suggested formation of new bonding involved Ca bridges.