This study compared multiple life cycle environmental impacts derived from two prospective farm intensification methods to support potential increased milk production in the Waikato region of New Zealand in 2025: (i) extra nitrogen (N) fertiliser at 137 kg N per ha (N scenario), and (ii) extra brought-in maize silage at 2,275 kg dry matter per ha (MS scenario). The cradle-to-farm gate perspective (i.e. environmental emissions starting from an extraction of raw material through to production of milk at the farm gate were accounted for) was used as a system boundary with 1 kg of fat- and protein-corrected milk as a functional unit. Allocation of environmental burdens between co-products of the inflows were based on an economic relationship, and for the outflow (i.e. milk and dairy meat), allocation was based on biophysical relationship (i.e. relative feed requirement for each of co-products). The results demonstrate environmental trade-offs between the two farm intensification methods, highlighting the relevance to assess a wide range of environmental impact indicators when doing an environmental assessment. The environmentally preferable intensification method will depend on priority and scale of environmental indicators of concern.
Integrated nutient and water management for sustainable farming, 2016, (29), pp. 1 - 7