Comment: Dr Jacqueline Rowarth believes that all lobby groups would do well to consider the advice of experts and knowledge brokers before they make decisions about production systems.

Greenpeace billboards (#too many cows) on the way to or from major airports have proclaimed that the two major fertiliser companies in New Zealand pollute rivers.

Complaints received by the Advertising Standards Authority that 'false claims were being made' were upheld, however, and Greenpeace lost the case.

Of course, the point for Greenpeace is that many people have already seen the billboards and then wondered whether the message (including the hashtag) was true.

Or, if they already thought that New Zealand has too many cows, in a process known as 'confirmation bias' they blame the fertiliser companies.

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Read more: Opinion: Farmers not being told full story on climate

The billboards have made a bigger splash than the complaints – and questions are being asked about how the damage can be rectified, particularly when Greenpeace based their justification on scientific research.

But not all science is good, and not all science is relevant. Not knowing enough about the topic to sort good from bad, and not knowing the context to identify relevance, can lead to false conclusions.

The Greenpeace belief is that fertiliser companies aren't required because organic production systems can feed the world.

Organic systems rely on 'natural' nutrient supply, perhaps from animal manure.

The supply of nitrogen, whether through animal manure or directly from plants, comes from biological nitrogen fixation. Clover in New Zealand pasture, for instance, supplies approximately 150kg/ha nitrogen annually (estimates do vary widely according to temperature and moisture).

There are research papers that support the notion that organic production systems can feed the world and do so into the future with an expanded global population. There are also scientific papers that suggest a reduction in fertiliser is possible without compromising production.

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

Know the starting point

But the point with all research is to know what the starting point is, what assumptions have been made, the basis of any calculations, and whether or not there are unintended consequences. The problem with the latter is that the end point might be less acceptable than the starting point.

At the opposite end of the research being quoted by Greenpeace is the calculation that without synthetic nitrogen the world agricultural system could feed only 3.1 to 3.2 billion people. The current global population is 7.65 billion, of which a billion are estimated to be undernourished.

The unintended consequence of removing fertiliser companies from the global food production system is easy to calculate – 4.45 billion people without food.

Read more: Listen: Should NZ ban synthetic nitrogen fertiliser?
Understand the flaws

The huge difference reflects some lack of understanding about production systems. Just comparing the yield from an organically grown crop with that from a conventionally grown crop does not reflect the whole farm or give an accurate picture of what happens over time.

Dr David Tribe, academic and scientist, the University of Melbourne, writes under the name of 'GMO Pundit'. He points out that it is the performance of the whole farming system over time that is most relevant, not just the output of any one farm field in one particular harvest season. He terms this 'farm system yield', as opposed to 'single season unadjusted yield'.

Colleague David Connor, Honorary Professor, the University of Melbourne, has also critiqued the research paper that formed the foundation for Greenpeace.

He points out that studies (including those quoted by Rodale, the famous organic research farm) often 'miss out' the land area allocated to green manure, and the nitrogen subsidies provided indirectly by synthetic fertilisers to organic operations via animal manure inputs.

Another flaw in calculations is that growing legumes for soil N (biological regeneration of fertility) interrupts growing food. Although some legumes are food crops (lentils, soybeans and chickpeas, for instance), when grown for food (human or domesticated animals), the fixed nitrogen is generally found in the seed that forms the food, not in the soil.

A further factor is that legumes are moisture and temperature dependent for growth and nitrogen fixation and cannot generally be grown year-round.

Professor Connor has expressed concerns that anybody using the research "to promote or support organic agriculture will have been misled and limited resources for research and development would be misallocated. The biggest losers are likely to be resource-poor farmers in developing countries".

Clover in New Zealand pasture, supplies approximately 150kg/ha nitrogen annually Photo / File
Clover in New Zealand pasture, supplies approximately 150kg/ha nitrogen annually Photo / File

Make informed decisions

Scientific research is vital, but as well as experts in science, with deep expertise in their areas of research, knowledge brokers are needed – people who understand the processes of science and the processes of policy, including the interface between them.

The role of a knowledge broker is to explain the evidence. Setting the evidence in context helps people to understand the issues and they can then make informed decisions.

There is a variety of organic production systems available in New Zealand that offer consumers choice – organic, vegetarian, halal, vegan, gluten-free…. you name it and New Zealand probably has it, somewhere.

But promoting any of these concepts on the basis of saving the world risks many different unintended consequences.

People's wellbeing, even their lives, are at risk while well-meaning people make statements based on inappropriate and flawed research. All lobby groups, not just Greenpeace, would do well to consider the role of experts and knowledge brokers.

- Science advocate and communicator Dr Jacqueline Rowarth CNZM CRSNZ HFNZIAHS has a PhD in Soil Science and has been analysing agri-environment interaction for several decades.