The agronomical balance in nitrogen at the commune level has been calculated between livestock-produced manure and the total demand in nutrients by crops and fish ponds, in the district of Vu Thu, Thai Binh province (Vietnam). Based on a conceptual Vietnamese-adapted model, calculations have underlined N surpluses in 50% of the studied communes during winter and the importance of waste waters that are expected to be the most important issue for environment regarding the 2010 provincial pig development plans.