Excerpt from “Manual on Pond Culture of Penaeid Shrimp”, ASEAN77/SHR/CUL3:
6.5 Construction in areas with acid sulfate soils
In areas with acid sulfate subsoils, special procedures are sometimes advisable in order to ensure pond fertility and prevent mortalities due to low pH. The economics has to be calculated for every farm to determine if such procedures are advisable. Some of the things which can be done are:
Excavate only enough soil from internal canals to construct the dikes and leave as much topsoil undisturbed as possible to serve as the pond bottom. In some cases, pumps might be required to fill this type of pond.
Scrap off the topsoil and set it aside. Then after the pond has been excavated, replace the topsoil over the pond bottom to cover the poor subsoil.
If the top layer of good topsoil is thick enough, alternate strips can be excavated twice as deep as necessary and then good soil from the unexcavated portion is placed in the deep portions to level the pond bottom.
Excavate the pond by sections. Excavate alternate 10 or 20 m wide strips within the pond and leave the strips between undisturbed. The pond is used for culture for several years, and after the excavated portions have aged, the remaining strips are excavated.
If the subsoil is not very acid, but has high potential acidity, a method of construction can be used in which the soil is kept moist so it will not be oxidized and become highly acid.
If acid soil, or potentially acid soil, has to be used for dike construction, the dikes bordering small nursery ponds can be surfaced with good topsoil. This is advantageous because acid runoff during rains has a greater effect in small ponds since the ratio of pond area to dike area is more critical.
If the dikes are to be constructed of acid soil, the nursery ponds should not be located next to large main dikes. This is recommended, because runoff is much greater from the large dikes than small ones, and as a result, more acid will be washed from them during rains.
If dikes are constructed of acid soils, the pond system should be designed to ensure that there is a minimum amount of seepage through the dikes into the ponds. This can be accomplished by having the pond water inside the pond higher than water outside the pond. Drainage canals should be constructed around the pond to make sure water does not stand there.
A berm can be constructed near the water's edge to catch acid runoff during rains and prevent it from washing into the ponds.
