Developing a protocol for bottom soil and water quality management in ponds for semi-intensive culture of black tiger prawn Penaeus monodon

This study was conducted at a commercial farm for semi-intensive culture of Penaeus monodon. The results of a series of preliminary trials were used to develop an integrated management protocol of grow-out ponds. This protocol was tested against the farm standard operating procedures. The proposed protocol enhanced shrimp production by augmenting the pond carrying capacity through the combined effects of a better and more stable phytoplankton bloom and a more suitable bacterial community structure. Ponds managed with this protocol, assimilated feed wastes more efficiently and had better water and soil quality than pond managed by standard procedures used on the farm. The main features of the proposed protocol were as follows: dry-out time for pond treatment based on soil organic matter and soil pH; heavier fertilization at the beginning of the crop; fertilization with a 10:1 N:P ratio; fertilization according to Secchi disk visibility; emergency fertilization for ponds with clear water; no routine lime applications; water exchange according to feeding rate; and raking the pond bottom during the crop.; This study also revealed that the following treatments were not beneficial: use of agricultural limestone and sodium nitrate in pond preparation and grow-out; fertilization with N:P ratios of 2:1 or 20:1; water exchange management according to projected dissolved oxygen concentrations. The development of a complete management protocol for water and soil quality through on-farm research was validated. The results attained may not be applicable to semi-intensive farms in other ecological settings because of environmental variation, but the methodology should be appropriate for a wide range of conditions in semi-intensive shrimp farming.