Assessment of salinity processes in rice - shrimp farming model in regions converted from agricultural lands to shrimp farming in Ca Mau province

Abstract

The conversion of inefficient agricultural and forest land to rice - shrimp farming model in the Mekong Delta in general and Ca Mau province in particular has brought remark benefits in terms of economic development. However, the introduction of salt water into some freshwater regions have created environmental problems, which is not only impact on shrimp farming but also on many other agricultural ecosystems. Land degradation and especially soil salinization is a concern not only for soil scientists and environmentalists but also for the land managers due to its multi-dimensional impact on national sustainable development. As such, it should be considered and addressed urgently. The case study has shown actual state as well as changes in visible soil salinity over time for the rice-shrimp farming model. ESP (exchangeable sodium percentage ) value is likely to decrease according to availability of rice crops and soil depth as well because there is rain water suppling during the harvest. At some of the sample points (CN8, ​​TPCM2, PT1), these are the abandoned fields and are drained in preparation for next shrimp after the failure of rice sowing, therefore the level of sodic soils has a tendency to increase according to shrimp crops. The process of deep salinity has been shown through some sample points such as CN2, CN5, TB2, TPCM2, sodic soils of the floor 20 - 40 cm is higher than the level of the floor 0-20 cm, desalination process has only reduced the amount of salt in the surface.