The Greens argue farmers can earn just as much from smaller herds if they count the costs they can save by buying less fertiliser and farming "smarter".
They claim that unless dairying becomes less intensive its pollution of freshwater resources will be self-destructive, clogging rivers and lakes with algal growth, rendering them unsafe for swimming and ruining the country's clean, green image. How serious is this?
Ideally, every watercourse in the country would be safe for swimming. But the country's earnings from intensive dairy production are also valuable. If there is a balance to be struck, it might reasonably fall some way short of a water quality standard requiring all rivers and streams to be safe for swimming. National has settled for a standard safe for no more than wading and boating. Fish in rivers should be safe to eat, too. But how many rural dwellers want to swim in a river?
If National's water standard offers a better balance, the Green's suggestions may be useful for enforcing the standard. Farms may need to be subject to a permit for stock numbers based on the nature of their soil and its drainage and the seasonal rainfall of their district. Irrigation may need permits too, and the Greens suggest a charge for the water drawn from rivers by irrigation schemes.
They are right that the Government should not be subsiding irrigation projects and providing free water for intensive dairying while proposing to spend $100 million trying to mitigate the nitrate run-off. With properly priced irrigation and better research on the soils of different districts, the country can continue to have both a growing dairy industry and clearer water in rivers and creeks. Whatever the make-up of the government after the election, the state of waterways in dairy regions looks certain to receive more attention.