Nieuws - 5 februari 2009


Extensive agriculture with fewer inputs such as fertilizer and pesticides is less sustainable than intensive agriculture. Even the researchers who came to this conclusion are surprised by it.

With the help of Dr. Frits van Evert of Plant Research International, an English research team calculated what a conversion to extensive farming of winter wheat, rape and potatoes would mean for the environment in England. They did the same for cattle and sheep farming. They made it a criterion that food production should stay the same. In the extensive variant, the environmental costs per hectare were lower, but more land was needed to produce the same amount of food. This makes it less sustainable than current intensive livestock and arable farming, the researchers will be claiming in a forthcoming issue of Agricultural Systems.
‘A life cycle assessment had already been done by other people', explains Van Evert. ‘It determined which inputs are needed and where they end up. Cattle feed ends up as manure, and enters the environment as nitrates and phosphates; so do pesticides. And this generates costs for drinking water companies. Diesel for the tractor, medicine from the vet, and soya farming for the feed all involve environmental costs beyond the farm. Using this data, we asked the question: can you reduce pollution through more extensive farming?’

For their calculations, Van Evert and his colleagues used a different method: total factor productivity. ‘In this model you enter all the costs, from seed to hire and depreciation of machinery, and you enter the profits. We included environmental costs such as greenhouse gases and nitrates. We expected extensive agriculture to score higher than the current intensive agriculture, but it didn’t.’

The main reason for this is that extensive agriculture would encroach on extra land where there is now forest, for example. ‘These areas are valuable as they store water, are home to birds and insects that are useful for pest control, and sustain a gene pool that is useful for further breeding. This value can be as much as thousands of dollars per year, and you lose much of it through extensive agriculture, because then more nitrates and pesticides are leached into the environment again.’

So intensive agriculture is more sustainable, although Van Evert is quick to add that sustainability is a broad concept. 'We are trying to interpret it concretely in terms of the inputs on a farm and the emissions of greenhouse gases and leaching of nitrates. But something that isn’t taken into account, for example, is the landscape value of extensively farmed land. If we forget something, I would say, give us the statistics and we'll integrate it into our model.'

Supporters of extensive farming will respond that they can accept lower production levels because it is more sustainable. But that is not what the research shows. When production goes down it is more sustainable to take the land out of production than to go over to extensive farming.

Professor Rudy Rabbinge came to pretty much the same conclusion in the report ‘Grounds for choices’ back in 1992. ‘What’s new about our research is that we allocate costs to environmental pollution, so that we can determine the exchange value between agriculture and environment.'