Knowledge or evidence

If you type ‘natural sequence farming’ into Google the engine returns a little over 200,000 hits. Enter this string into Google Scholar and it returns over 200,000 scientific papers, albeit not all of them about this topic. Do the same on any of the specialist scientific referencing software like Mendeley or Zotero and a similar thing happens — a mountain of knowledge appears before you, daunting and unscaleable. And just like the Himalayas this knowledge mountain is getting bigger by the day, much bigger.

Around the world there are over 16,000 universities. Given a conservative assumption of 5 researchers per university with an interest in farming or landscapes or conservation there are at least 80,000 people paid to generate evidence on farming systems. Assuming they each place one peer-reviewed pebble onto the knowledge mountain each year, then tomorrow’s Google Scholar search will return 200 more entries than today. A daunting prospect for anyone who just wants some evidence.

Back in the day, it was possible to actually be abreast of the available knowledge in a discipline. You could find a review article or two where scholars had spent a year or more on a synthesis of the available research and practice on a topic. These reviews were specific and they retained a sense of proportion. Journals that specialised in them were the place for any aspiring scholar to begin serious learning. The knowledge universe was tractable and, with a bit of effort, it could be assimilated by a keen individual.

Now there is so much material that such scholarly works of summation created at leather bound desks piled high with erudite tomes are near impossible, quaint even. More new research appears each week than old timers would have seen in a decade.

What happens today is that search engine power must be unleashed at the knowledge mountain to retrieve all material that fits carefully selected keywords. The many thousands of records are filtered through a set of rules to cull them back to manageable numbers. Then filtered some more on the quality of the evidence, leaving some data in and some out. Finally the evidence still intact requires some synthesis. This process is formalised now as a systematic review and after earning its spurs in the health sector the process is applied more and more in environmental disciplines.

Natural sequence farming is a method for the rehabilitation of degraded agricultural land developed by Peter Andrews, a horse breeder from NSW. It worked in spectacular fashion on his Tarwyn Park property but the process is controversial involving mechanical landscaping and the use of any available material and vegetation, including weeds, to hold water on the landscape. It is way outside the comfort zone of most farmers and conservationists alike.

Anything this unusual attracts the attention of naysayers who want to know exactly how these crazy ideas work. After all, no one has ever used them before.

The search on the keyword string suggests that the topic appears well covered by scholars. Once the irrelevant returns are removed there are perhaps 100 or so citations. Not a mountain certainly but scientists have had a look at the idea through their inference lens with some even gathering data.

After filtering these citations for their relevance and adherence to scientific protocols it turns out that the overall logic of natural sequence farming — retain water in the land by spreading it out across the upper catchment that then feeds vegetation through subsurface flows — is supported by settled science from soil ecology, hydrology, geomorphology, and vegetation ecology. The theory confirms that holding more water than usual on a landscape will prime biological activity and in wet and dry systems prone to runoff, holding the water up with physical barriers is indeed logical.

Theory is sound but does it work in the real world? To answer this empirical evidence is needed. So far there are no systematic evaluations of the technique or formal experimental trials at multiple sites. Consequently, there is limited scientific evidence to predict what the benefits will be to production or environmental values or where and at what rate any benefits will accrue. So whilst it makes logical sense as a management practice that should benefit production, there is very little evidence for where (or when) it will work.

And then natural sequence farming is just one of several options to restore or rehabilitate degraded landscapes. But there are no formal comparisons with other land management options designed to achieve similar environmental or production values.

Whilst there is a great deal of expert opinion and experience, there is not enough inference from quality research studies at the top end of the evidence hierarchy to predict what to do where, when and how much in order to obtain cost-effective benefits. So despite the obvious potential of natural sequence farming for farmers and the commons, questions remain over the cost-effectiveness, scalability, and ongoing benefits its implementation.

You can imagine the response of the naysayers.

This is a pity because we need every rehabilitation technique we can get our hands on. Far too much land is underproductive, degraded or unfriendly to beneficial wildlife. Farmers benefit from rehabilitation tools that they can use. But to persuade them requires evidence, proof that they would get a benefit and not be wasting time, effort and money, none of which they have to spare.

A quick evidence review suggests that for some issues, like natural sequence farming, knowledge of the fundamentals is not enough. This kind of environmental management needs empirical tests on the ground to support the theory. There was knowledge but not enough evidence to back it up — a salutary lesson for those who fund research and for those who advocate.

Evidence reviews are a speciality of alloporus. They are fast and generate knowledge to support all sorts of environmental decisions.


This post first published by Mark Dangerfield on LinkedIn Pulse

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