Are diverse species mixtures better pastures for dairy farming?

Pressure on New Zealand's largely pasture-based dairy industry has grown with a drive to increase production, expansion into new regions and demand for farmers to mitigate environmental impacts e.g., leaching of excess urinary nitrogen. A 3-year trial in the Waikato investigating the use of mixed pasture (e.g. perennial ryegrass, white clover, prairie grass, lucerne, chicory and plantain) showed similar annual dry matter (DM) production to standard pasture (perennial ryegrass and white clover) with greater yields of mixed pasture during summer (December, January, February) when lucerne and chicory grew better than perennial ryegrass in the warm, dry conditions. However, this yield advantage did not persist during the winter (June, July, August). Milk yields from cows grazing the mixed and standard pasture were similar. The mixed pasture retained a high level of species diversity and, while a single "magic bullet" is an unlikely solution to the challenges facing dairy farmers, increased species diversity could reduce risks and increase pasture stability. Keywords: pasture species diversity, dry matter yield, milk, nitrogen