Current challenges for New Zealand livestock farming systems include soil erosion, water quality, greenhouse gases (GHG), and indigenous biodiversity. Industry data were used to quantify changes in emissions of the major livestock sectors from 1990, by examining inputs (e.g., livestock numbers, fertiliser) and outputs (e.g., GHG, nitrate leaching (N), saleable products) using Overseer. Productivity gains were significant for extensive sheep and beef farms, from 107 (meat + wool) kg/ha in 1990 up to 167 kg/ha in 2012. Gains were modest for intensive sheep and beef farms in this period (from 219 up to 238 kg/ha). Extensive sheep and beef increased from 3370 to 3997 kg/ha of GHG and N leached from 12 to 14 kg/ha. Intensive sheep and beef farm systems showed negligible change in N leached, while GHG emissions rose from 4167 to 4470 kg CO2-e/ha. North Island dairy farms increased from 672 to 1000 kg milk solids/ha, from 11341 to over 12000 kg CO2-e/ha of GHG and N leached increased from 44 up to 50 kg/ha. All farm systems delivered more product in proportion to GHG and N per hectare per year. Potential scenarios for the sheep and beef sector into the future were investigated, by examining the influence of ongoing increases in reproduction of ewes, lamb growth, hogget lambing and moving away from breeding cows and older cattle could have on future productivity gains and environmental impact. With the area in pasture likely to continue to decline in extensive livestock systems as outstanding environmental issues are addressed, the potential exists to offset > 20% of livestock GHG emissions. Intensive systems have fewer opportunities to make production and eco-efficiency gains, with less scope to reduce their impact.
New Zealand Journal of Animal Science and Production, Volume 79, Palmerston North, 43-55, 2019
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