Reworking our dairy systems

MYTCHALL BRANSGROVE/Fairfax NZ

CAPITAL HUNGRY: For a shed that is suitable just for wintering dry cows, the overall additional capital requirement will be about $2000 per cow.

OPINION: Many farmers will resist it fiercely, housing our dairy herd in sheds is almost inevitable.

The New Zealand dairy industry has always prided itself as being different. Whereas most other countries developed their dairy industries based on the housing of cows for much or all of the year, the New Zealand industry has always been pasture-based. The cows harvest the grass themselves, the cost of production has been low, and the image was of "clean and green".

Alas, we now know the image of "clean and green" was never quite true. Although a huge amount has been done to clean up the industry, with fencing of waterways, nutrient budgets and meticulous management of effluent from the milking shed, there is a fundamental problem still to be tackled. This fundamental problem is the concentration of nitrogen in the urine patches which grazing cows leave behind.

The dominant belief among scientists is that when a cow urinates it deposits nitrogen in the urine patch at up to 1000 kg per hectare. Not all of my animal scientist colleagues are convinced about this specific number, but regardless of the exact amount, it is inevitable that there will be significant nitrogen leaching from urine patches deposited in autumn and winter.

It does not matter what is done in terms of reduced stocking rate or reduced fertiliser or different grasses. As long as the cows are grazing the paddocks in autumn and winter, then there is going to be significant loss of nitrogen into waterways and underground aquifers.

There are four possible strategies.

The first option is to do nothing. That would mean the leaching problem would get even worse. But that is not an option because New Zealand society will not allow it.

The second option is to allow no further expansion of the dairy industry. That, too, is not an option because even with no further industry growth there will be further build-up of nitrogen in the waterways and aquifers.

The rest is here:
Reworking our dairy systems