抄録
Rice cropping in the coastal areas of the Mekong Delta is affected by salt intrusion during the dry season. Construction of sluice gates and dykes for salinity prevention has changed the water regime for rice farming. We focused on a case in which rice production did not increase appreciably by the salinity control projects implemented in Go Cong District, Tien Giang Province, Vietnam. We conducted a socio-economic survey and analyzed water quality in the river and canals in two communes: Phu Thanh (PT) and Phu Dong (PD), located in the lower reaches of the site, where five gates and dykes had been installed along the coastal line in 2001. The annual rice yield (t/ha/year) increased by 31% at the location near gate g1 (PT-N) after the construction of sluice gates and dykes, while at the location far from g1 (PT-F), it decreased by 30%, and in PD the yield did not change significantly. The construction has extended the salt free period, and allowed more farmers to practice double cropping using a modern variety at PT-N. However, at PT-F, the construction exacerbated the acidification in the canal water at the beginning of the rice season, resulting in the reduction of the number of croppings. At PD, the number of croppings did not increase due to the severe water acidity in the canals.
