Characteristics of soil acidification of haplic Acrisols on ancient alluvial deposits under intensive cassava cultivation in Chau Thanh district, Tay Ninh province

Abstract

This paper clarified the characteristics of soil acidification of haplic Acrisols on ancient alluvial deposit under intensive cassava cultivation in Chau Thanh district, Tay Ninh province, Southeastern Vietnam. Soils were sampled at 3 intervals (0-20, 20-40, 40-60 cm in depth) in 12 sites of intensive cassava cultivation and geochemical parameters related to soil acidity were analysed. The haplic Acrisols under intensive cassava cultivation showed quite high levels of active and exchange acidity (pH H2O 4.40±0.11, pH KCl 3.98±0.07). The hydrolytic acidity and Al saturation level were also high (respectively 4.52±0.37 meq/100g and 57.64±6.41%) while the exchange alkali and alkaline earth cations were very low (Ca 2+ 0.76±0.25 meq/100g, Mg 2+ 0.88±0.85 meq/100g, K + 0.16±0.06 meq/100g in the top layer). This exhibited a limit for mineral nutrients and risk of Al toxicity to cassava plants. If the area for intensive cas-sava cultivation is expanded and the high-yield cassava varieties are applied, the risk of soil acidification will be expected to be highly serious. It is needed to clarify the processes involved and to establish measures to reduce soil acidification and stabilize cassava production in the study area and Tay Ninh province.