Nitrogen efficiency in mixed farming systems

The problem of nitrogen surpluses in Northwestern Europe is related in part to recent segregation of animal and crop production. A long-term solution can be found by re-integration of the main agricultural production components into mixed farming systems. In a new classification scheme of farming systems, high-input systems are placed in a sequence of modes in agriculture that each address sus-tainability problems in different ways. In this classification scheme, New-Conservation Agriculture (NCA) is considered to be a new mode of farming that aims to replace losses from the system, whilst not overloading it through critical use of non-renewable resources. Mixed farming systems that integrate crops and livestock are a typical example of NCA. The advantageous environmental features of mixed farming systems are illustrated by the favorable nitrogen balance of two experimental prototypes (a conventional and an organic one) where arable, dairy and sheep farming are integrated to a high degree. However, particularly the plowing of grass/clover swards caused serious problems on both farms regarding seedling survival and product quality in sugarbeet, maize, onion, and potato crops. This was due to the occurrence of large pest populations of leatherjackets (Tipula paludosa) and wireworms (Coleoptera: Elateridae)