The pH buffering capacity of Acrisols under cassava production in Southeastern Vietnam, Chau Thanh district

Abstract This study examined the pH buffering capacity (pH BC ) of haplic Acrisols under intensive cassava production in an upland area of Southeastern Vietnam where accelerated soil acidification has occurred. Soil samples (0–20, 20–40 and 40–60 cm) were taken at 12 sites under cassava and three sites under secondary dipterocarp forest as reference. The pH buffer curves were linear in the pH H2O range from 3.97 to 5.24, corresponding to a pH CaCl2 range from 3.74 to 5.20. Soil pH BC were low (1.16 ± 0.13 cmol/kg/ pH ) and correlated significantly with pH , Aluminium (Al) and Al‐related components. The results suggested that exchange acidity contributes significantly to soil's buffering capacity in acidic soils with low organic carbon. It also pointed to the possibility of using indicators of acidity to estimate soil pH BC . The low pH BC indicated a high risk for further acidification and also pointed to the possibility of using lime to remediate soils. Either acid buffering capacity or lime buffering capacity not pH BC in general should be considered, respectively, in acidification and liming studies. Factors and processes involved in soil acidification and liming need to be addressed as a background for soil remediation in the study area.