A reduction in cow numbers would have unintended consequences - Rowarth

Maintaining dairy cow numbers at peak productivity remains the best option for both the economy and the environment, ...
RICKY WILSON/FAIRFAX NZ

Maintaining dairy cow numbers at peak productivity remains the best option for both the economy and the environment, Jacqueline Rowarth says.

OPINION: Suggestions that New Zealand should remove 80 per cent of dairy cows to improve the environment overlook both the direct economic effects and the unintended environmental consequences.

Neither would be positive.

For the economy, the latest Situation and Outlook for the Primary Industries released at last month's Fieldays provides both data and predictions.

By 2020, the Ministry of Primary Industries forecasts that the value of dairy exports will have grown by 26 per cent to $17.7 billion. Meat and wool will have decreased by 2.2 per cent to $8.8b and horticulture will have grown 37 per cent to $5.7b.

READ MORE: Dairy cattle numbers fall for first time since 2005

Examining current export receipts and areas gives an estimate of value per hectare. The national dairy herd occupies only 6 per cent of New Zealand at 1.7 million hectares. Dairy earned $8265 per hectare in 2015. This year, the forecast is for $7782 a hectare.

Horticulture, which occupies half a million hectares produced $8330 in 2015 and this year, the forecast is for $10,030. In contrast, the overall income for sheep and beef is $783 per hectare, with little change for this year.

Replacing dairy with horticulture might have some economic merit, but land suitability has to be considered, as does the supporting infrastructure and inputs.

The point about any land-based activity is that it suits the topography and climate, which interact with the parent material to create the soil. Farmers and growers understand the nature of the interaction, and then manage the deficiencies – fertilisers, irrigation, shelters, for instance.

They also consider the infrastructure, processors and markets. Land that can be used economically and environmentally sustainably for horticulture has mostly been converted already.

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Dairy farms tend to be in flat to rolling countryside where grass grows well and cows can create milk very efficiently. Fattening beef and sheep is possible on this land, but top intensive drystock farmers are still not able to make as much money from this land as top dairy farmers.

Beef and Lamb New Zealand have shown that they can make as much money as average dairy farmers, but few people are aiming at average – they aim for the best they can be.

There are also detrimental environmental impacts to be considered. Research on the Canterbury Plains reported in the media last year indicated that dairy conversions involving fertiliser and irrigation, actually increased organic matter.

The reverse is also true. And when organic matter breaks down, nitrogen is released as is carbon dioxide.

Massey University's professor Tony Parsons has examined the land-use challenge with funding from the New Zealand Agricultural Research Centre (NZAGRC). He has calculated that at a given N input, dairy produces two to three times as much food, similar or less methane and less than half the amount of nitrogen loss.

He has also shown the use of supplements improves efficiencies. Combined with strategic use of shelters and feed pads, nitrogen losses can be reduced.

The implications of this work are, that all other things being equal, changing from dairy cows back to beef and sheep will increase nitrogen losses - both to water and to the atmosphere.

Maintaining the national dairy herd in peak productivity remains the best option for both the economy and the environment.

- Jacqueline Rowarth  is the professor of Agribusiness at the University of Waikato.

 - Stuff

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