In industrialized livestock production in Europe, regulations
limit the amount of manure that may be applied on arable
land mainly to prevent over application of the nutrients nitrogen
(N) and phosphorous (P), e.g. the Nitrate Directive for
the EU-27 (EC, 1991) and the Minerals Policy Act for the
Netherlands (RVO, 2005). These regulations strongly affect
regions with high animal density and limited arable land,
such as areas with intensive pig and poultry farms in densely
populated areas. In this situation, surplus nutrients or surplus
manure that may not be applied must be treated or exported.