South Canterbury's massive year-on-year increase in cow numbers may be curbed by water availability and future environmental regulations.
The region has had a 157 per cent increase in dairy cow numbers in the past decade, from 74,945 in the 2001-2002 season to 193,092 in the 2011-2012 season, according to figures from dairy genetics company Livestock Improvement Corporation and DairyNZ. The district now has the largest herd size in New Zealand.
It had the capacity to increase numbers, but these could be curbed by tighter environmental regulations, Lincoln University farm management lecturer Marv Pangborn said.
"We can handle more cows and more farms, but from an environmental point of view, regulators will make those decisions for us."
Environment Canterbury's Land and Water Plan and agriculture's inclusion into an emissions trading scheme in the future could slow growth in cow numbers, he said.
The region's average dairy herd size has increased from 539 to 779 cows in the decade and the amount of land converted to dairying had almost doubled, from 26,637 effective hectares to 56,169ha.
The statistics came as no surprise and matched his own studies on the growth of the dairying industry, Mr Pangborn said.
The growth of cow numbers was caused by dairying being the most profitable form of land use on irrigated land and the poor returns from other competing land users, such as the sheep industry.
"The loss in income in wool has been a big deal in the sheep story," he said.
A lot of the land-use change had happened alongside the growth in irrigation. Once a farm has irrigation, it provides the farmer with different farming options.
An increase of 33,000 cows in the 2008-2009 season was of no surprise as farmers converted to dairying after the high payout that year.
"It makes sense that people will chase the big payouts. If it had happened in lettuce production, we would see people producing lettuces," Mr Pangborn said.
South Canterbury Federated Farmers dairy section chairman Ryan O'Sullivan said the proportion of land area farmed by cows was modest: "If you compare it to areas like the Waikato where there is wall-to-wall dairying, we're miles away from that."
He said the limiting factor for further dairying growth in South Canterbury was water availability.
"I don't see any more conversions locally without more water being brought into the area," he said.
- The Timaru Herald