contributes mostly for the rice export. Nowadays, the impacts of global climate change are detrimental to agricultural production, especially, the lack of freshwater during the dry season. In addition, area of the triple rice cropping has increased due to the dyke system which has prevented the field from deposition of huge amount of sediment from annual flooding. This research consisted of two experiments: (1) effects of combination of alternative wetting and drying irrigation (AWD) and phosphorous reduction on the rice growth, yield and economic efficiency in the summer-autumn 2012 and winter-spring 2012-2013 crops; (2) comparison of rice growth and yield in the fields with and without sedimentation under unsupplied phosphorous fertilization in winter-spring 2012-2013 crop. The experiment was laid out on light acid sulphate soil where rice is doubled grown at TaDanh village, TriTon district, AnGiang province. The results of the first experiment showed that without or reduced phosphorous application did notaffect thegrowth andyieldof rice in two consecutive crops and saved from 36.5 to 73kg P2O5/ha. The AWD irrigation technique reduced the investment costs but rice performance was stable in the range of 7.3 to 7.7 tons/ha/crop. This water management strategy saved from 1,336 to 1,352m3 water/ha, about 46% of total irrigated water quantity leading to an increase profitability of VND 4.9million per ha. pHandEC of field water did not differ between the AWD treatment and continuous flooding. The combination between AWD irrigation and phosphorous reduction caused no change in yield components, phosphorus level in rice stems and leaves, SPAD values as well as above ground biomass of rice plants. The results of the second experiment showed that the rice growth and yield in the fields with and without sedimentation under unsupplied phosphorous fertilization were
not significantly different. It is suggested that the experiment be continued for several years to obtain reliable results.