Evaluation of water management strategies for acid sulphate soils using a simulation model: A case study in Indonesia

Abstract

Reclamation and drainage of potential acid sulphate soils results in pyrite oxidation, acidification and release of toxic elements, hampering it's use for agriculture. Moreover, forest reserves and other ecologically valuable habitats located downstream of reclamation areas may be disrupted. Proper water management is essential for a sustainable reclamation of acid sulphate soils. The computer model SMASS (Simulation Model for Acid Sulphate Soils) was developed to predict the effects of water management on soil and water quality in acid sulphate soil areas. SMASS was applied to evaluate six different water management strategies for the Barambai area in South Kalimantan, Indonesia. These strategies were aimed at oxidation of all pyrite in the topsoil to prevent recurrent acidification during dry periods in the future. Model computations showed that all the proposed water management strategies will fail to achieve good soil and water conditions within a few years. Continuation of the present water management will result in poor rice yields and environmental damage for at least another 10 years. By application of a shallow drainage system to 30–40 cm, soil and water quality will strongly deteriorate during the first 3 years. Thereafter, the soil will be less unfavourable than if the present water management had been continued. The case study presented illustrates how the SMASS model can be applied to make a scientifically based evaluation of water management strategies. However, technical, economical and social factors should be considered as well, when deciding which water management strategy should be implemented in practice.