In order to help Bac Giang and the other Northern midland provinces of Vietnam to improve commercial sweet potato production, during 2009-2011, the Field Crops Research Institute conducted a series of experiments to develop an integrated cultivation practice for better root yield and economic return of this crop under the local conditions. The study results highly recommend to fertilize the crop grown either in the spring- or winter-season with a rate of 7-8 ton of farm yard manure (FYM) or 5-6 ton of rice straw plus 60 kg N + 30 kg P2O5 + 90 kg K2O/ha
the most suitable planting time for the winter crop is from 15 to 25 September and that of the spring crop is between 20 January and 10 February
proper planting density for winter crop is 37,500 - 41,500 cuttings/ha and that for spring crop is 33,500 - 37,500 cuttings/ha. Where water is available, the crop should be furrow irrigated in 3 times at 30, 60 and 90 days after planting. Sex pheromone traps if placed at a density of 6-10 traps/l000 m2 of crop area is a good method to control sweet potato weevils under fanners condition. For commercial sweet potato production, it is better not to intercrop sweet potato with other crops. The results of the pilot sweet potato production conducted in the winter crop of 2011 using the FCRI newly developed varieties and integrated cultivation practices showed an increase of 21.2-29.1 percent in root yield and that of 60 percent in net profit as compared to the use of local check varieties and the farmers practice.