Nitrates directive requires limited inputs of manure and mineral fertilizer in dairy farming systems

Properly managed manures have a high fertilizer value and are thus a valuable source of nutrients in forage production systems. An efficient utilization of these nutrients, however, is limited by the crops demand for nitrogen (N) and phosphorus (P). Moreover, environmental goals implied by the EU Nitrates Directive impose constraints on the use of manure and mineral fertilizer. In the present study a simulation model is used to explore limits on the use of cattle slurry and mineral fertilizer in grass and silage maize production in the Netherlands