The role of supporting ecosystem services in conventional and organic arable farmland

Ecosystem services (ES) in agriculture are vital for the sustainable supply of food and fibre, but their economic value has rarely been evaluated in agricultural crops at field level. The current study quantified three key supporting ES associated with highly modified arable landscapes in New Zealand using a novel, experimental 'bottom-up' approach. These services were biological control of pests, soil formation and the mineralisation of plant nutrients. The results showed that background (unmanipulated) biological control of pests in conventional arable farming were severely and significantly reduced compared with fields under organic management. ES associated with soil formation and mineralisation of plant nutrients did not differ significantly between organic and conventional fields. This study also estimated the economic value of these services using experimental data, in contrast with 'value transfer' approaches used in previous studies. The total economic value of these three ES was significantly higher in organic fields as compared to conventional ones. Yields obtained in organic fields were similar to those in conventional ones. This work quantified the role that land management practices play in the maintenance and enhancement of supporting ES in agricultural land and showed that conventional New Zealand arable farming practices can severely reduce the ecological and financial contribution of some of these services in agriculture.