NPK farm-gate nutrient balances in dairy farms from Northwest Portugal

摘要: Farm-gate nutrient balances (N, P and K) were analysed in three groups of dairy farms from NW Portugal – medium, intensive very during 3 consecutive years, 2003, 2004 2005. Results showed that the N surplus per hectare with values between 200 850 kg ha −1 was positively correlated milk production stocking rate farm, whereas K surpluses fewer variations groups. In all main inputs mineral fertilizers feed concentrates output. Farmers involved study advised terms management significant decreases observed years study, mainly due to a decrease inputs, namely fertilizers. We conclude advisory campaigns among farmers are efficient reduce surpluses. The losses via NH3 emissions at farm scale also estimated accordingly IPCC emission factors it appeared such had be considered together when strategies enhance defined. On average, higher studied relatively other European regions, but present lower unit (kg milk) as well efficiency. Nevertheless, target limit 450 for should easily reached first step by most improving scale. However, more efforts will necessary NPK mean basis found regions less systems. © 2008 Elsevier B.V. All rights reserved.