Respiration in mixes of sandy and clay soils: Influence of clay type and addition rate

Abstract

In an incubation experiment, a sandy top soil was mixed with kaolinite- or smectite-rich clay soil at 15, 22.5 and 30% clay addition rates. Compared to sandy soil alone, smectite clay soil addition at 22.5 and 30% reduced cumulative respiration per g organic C whereas kaolinite clay soil addition had no effect. This can be explained by the higher surface area and cation exchange capacity of the smectite compared to kaolinite clay soil which protects native organic C from decomposition by binding.