What is the environmental impact of sheep dairying?

Potential environmental effects of dairy sheep

There is little knowledge about the environmental impacts of dairy sheep. Evidence is required to support the reputation of sustainability and assess whether dairy sheep milking may be a suitable land use in nitrogen-stressed catchments.

Research was undertaken to quantify some of the potential environmental effects of dairy sheep production systems in New Zealand. The four goals were:

  1. Quantify nitrogen losses to water
  2. Estimate the intensity of nitrogen and greenhouse gas emissions
  3. Characterise effluent and refine good management practice guidelines
  4. Refine farm system models


Two experiments were conducted to estimate nitrate leaching beneath grazing sheep, in two contrasting soil types. For lighter soils, the porous ceramic cup method was used, and for the heavier soils, hydrologically isolated plots.

We sampled effluent from ponds on a range of sheep milking farms to characterise the nutrient content.

A nitrogen balance model was used to investigate nitrogen flows within a farm as well as inputs and outputs from a farm.

We used desktop-based calculations to estimate greenhouse gas emissions (GHG) from real farm scenarios.


Our studies found:

  • Nitrogen leaching losses appear to be lower per kilogram of Nitrogen excreted (from dairy sheep to cow)
  • Dry matter intake is the key driver of both Nitrogen leaching risk and GHG emissions in dairy sheep (and cow) systems
  • On a per hectare basis, GHG emissions appear to be lower from dairy sheep systems compared to dairy cow
  • Effluent from dairy sheep should be managed by following the good management practice guidelines for the dairy (cow) industry
  • Farm system models like Overseer can be updated for dairy sheep when critical data gaps are filled 

Environmental attributes of dairy sheep farming

The full report from the research project is available for download here.

Find out more (pdf 1.6 MB)

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