Comment: We should be having an open and evidence-based discussion about the impact of removing pastoral farming on both the environment and the economy, writes Dr Jacqueline Rowarth.

One of the ideas being promoted in the media is that farmers can make more money by decreasing the number of animals on their farm.

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This, we are told, will also improve the environment. Greenpeace were active on the topic in 2017 with their "Sick of too many cows?" document.


It cited impacts on water and public health, only some of which are supported by science. Despite this, the statements about "fewer cows and more money" continue.

Nobody in the media appears to be chasing the question which might lead to insight and understanding - "If farmers can make more money by destocking, why aren't they doing it?"

The answer is that some of them can and have, but what has been found for a few regionally specific case studies cannot be applied to all farms in New Zealand. For some, a decrease would mean they are no longer financially viable.

Important factors in any assessment are starting point (stocking rate, feed supply, infrastructure) and the soil type, topography and climate for the farm under consideration.

It is also important to understand the research providing the foundation for the statements.

An early piece of work on farms in the upper catchment of the Waikato showed that it is possible to maintain a return on capital (ROC) with a stocking rate below average for the area. The example, featured in rural media was a stocking rate of 2.67 in comparison with 2.82.

This is quite a small difference and ROC is not necessarily the same thing as "making more money".

Environmental modelling using OVERSEER did indicate a reduction in nitrate leaching from 28 to under 20kg/ha. However, a change in the version of OVERSEER accounted for between 30 and 50 per cent of the reduction.


The research concluded: "There will be different solutions for each farm to achieve true resilience, and the most appropriate solution will largely be governed by the risk preferences of the business operator."

Despite this, environmentalists not involved in the research have continued to make sweeping statements in the media along the lines of "a reduction of 20 per cent in cows from most of the farms in New Zealand, would actually make the farmer more money".

Lincoln University Dairy Farm (LUDF) has been used as the example of success. During the first decade of the century, stocking rate was increased. By the 2010-11 season it was 4.3; the district average was 3.2. A change to precision dairying in 2012 reduced the stocking rate to 3.9, and then again to 3.5 for the 2014-17 period.

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This was associated with a decrease in nitrate leaching (modelled through OVERSEER) from 45 to under 30kg/ha. A report from last year indicated a further decrease in stocking rate to 3.4 (the same as the region average).

Precision dairying has involved selecting for cows of high genetic merit, and improved pasture management.

Pasture is now grazed at 3 leaves (on average) instead of 2.0 to 2.5, and residuals are higher at 1550 to 1600 kg/ha than the hard grazing once promoted.


This regime fits the DairyNZ advice on optimising pasture management, and the farm has improved financially.

LUDF is a research farm and must test different ideas to assist scientists to develop ever-better systems. A negative result can be as helpful as a positive.

LUDF has decreased its stocking rate and is showing good financial performance – but decreasing stock numbers from now would result in financial problems. This is true for the many farms already being managed optimally

Optimisation is the key, not just for pasture management, but also for any inputs such as irrigation, nitrogen and supplementary feed, all with the goal of meeting the needs of the animal to achieve optimal performance with minimal environmental impact.

Dr Jacqueline Rowarth. Photo / Supplied
Dr Jacqueline Rowarth. Photo / Supplied

Good farmers operate within a dynamic management system where inputs and outputs are juggled constantly as temperature, moisture and prices change.

It is very difficult for environmentalists to see all the issues. Their prime focus is the environment, of course, and they have raised awareness that New Zealand is not the same as it once was.


Of course.

People live here and people have impacts on everything. They also have expectations about lifestyle and economic growth.

Environmentalists driving New Zealand towards lower stocking rate have been heard to suggest that New Zealand would actually be better off without ruminants.

If this is the real goal, we should be having an open and evidence-based discussion about the impact of removing pastoral farming on both the environment and the economy.

The questions to be asked include how ugly post-Covid recovery would be without agriculture, and whether the environmental outcome would be as pretty as pictured.

• Dr Jacqueline Rowarth CNZM CRSNZ HFNZIAHS has an agricultural science degree with honours in environmental agriculture and PhD in Soil Science. She is a farmer-elected Director on the Boards of DairyNZ and Ravensdown. The analysis and conclusions above are her own.