Potential for land use change to dairy i

Southland has witnessed a pronounced change in its agricultural landscape in recent years. Greater profitability of dairy relative to sheep farming has led to a large number of dairy conversions over the last 20 years, with the scope for further substantive conversions into the future. The economic and social benefits have been extensively reported, but less is understood about the environmental impacts associated with this land use change. To investigate the potential effect of land use change from sheep and beef to dairy on economic and environmental outcomes in the Southland region of New Zealand, farm-scale enterprise simulation models were linked with spatially explicit land resource information. By overlaying individual farm parcels with land resource information, land area and topography data for each farm were attained. Estimated pasture production (PP) for each land use capability (LUC) Class provided indicative data for the modelling exercise on the productive use of the land across the region. The approach provided a method for the expansion of farm scale modelling to a regional scale. Estimates of annual nitrogen (N) leaching values from dairy farms ranged from 21 to 44 kg N/ha, and were higher for farms with greater pasture production potential, due to the greater amount of N cycled for well and poorly drained soils.