The latest dairy statistics show the South Island now accounts for almost 40% of the country's dairy production, and Canterbury has the highest-producing dairy cows.
The 2009/10 statistics released by the Livestock Improvement Corporation and DairyNZ show the highest average per cow production - 384 kilograms of milk solids - was recorded in North Canterbury.
That region also had the highest herd and hectare production figures.
South Island farms have, on average, more than twice the per herd production that the North Island achieves, reflecting a combination of larger herd sizes, a higher stocking rate and more kilograms of milksolids per cow.
Nationally there was a 3.3% increase in milksolids processed in the 2009/10 season.
That's attributed to an increase in the number of cows being milked, which rose to 4.4 million, surpassing New Zealand's human population.
The average herd size also continues to grow. It has tripled in 30 years to 376.