Sustaining conflicting ideas

1 Dec 2017

Whenever I walk to Cambridge Railway Station I pass new buildings that are divided into ‘sustainable’ student flats. Each time I see that slogan I think “what makes them sustainable?”. They look like all other new build flats, which are no doubt well insulated. I also suppose they may have a few solar panels on their flat roofs. But sustainable no!

Sustainable is the in-word when discussing agricultural systems. It has been a ‘must’ for research applications for the last 25 years or so. However, it remains undefined and somewhat of a mystery to many. A bit like the student flats.

I recently attended a discussion on sustainable agricultural production at the Cambridge Department of Plant Sciences. For one speaker the answer was easy – ban cattle and sheep. She said that dairy cattle alone are responsible for 10% of the world’s greenhouse gas production. There is no doubt that agriculture is a major source of greenhouse gas production; I have not been able to verify that particular figure but it could be in the right ball-park.

Getting rid of cattle and sheep will also reduce the need for growing arable crops to feed them, further reducing the footprint of agriculture. I did ask the question what would happen to the upland farms if sheep production were banned. They not only provide an income and an infrastructure but also many tourists appreciate the landscape of fields being grazed by sheep. She was unrepentant and added that farming the uplands is responsible for flooding in many parts of the country.

Defra secretary Michael Gove is now talking about the loss of agricultural soils. He made the claim that Britain has lost 84% of fertile topsoil since 1850 and erosion continues in some areas at between 1cm and 3cm a year. I have been working in agriculture all my life and I do not recognise those figures. Hence, I read what I am pretty sure is the source document. It seems that the quoted losses are just for the peat fens and not all agricultural soils. Again, all agricultural production is implicated from a quote out of context. I am not sure if Michael Gove would recognise a fen peat if it hit him in the face but his advisers should know better. It should also be noted that in the 1960s and 1970s there was active state-funded research trying to find approaches to minimise carbon losses from the fen peats but, according to my knowledge, no research has since been done. There is one positive measure that could be adopted to prevent the loss of food production from organic peat soils and that is to prevent the construction of even more solar farms on this valuable resource.

Farmers do recognise there is a soil health issue and have moved much more positively than any policy maker. They are anxious to improve soil conditions and many use as much organic material as they can get. However, according to a House of Lords committee, there are apparently still some potential organic sources not being used. The recent widespread adoption of cover crops on the lighter and medium soils must be reducing soil erosion although their longer term benefits remain a subject of debate.

Large increases in soil organic matter remain an impossible task however desirable the objective. The necessary large scale use of organic manures is not possible because of limited supplies. The only other option is to sow long-term grass leys. Defra became keen on this idea a few years ago but then looked at the experimental data. For instance, in the often quoted ley fertility experiments carried out on the MAFF Experimental Husbandry Farms in the 1950s and 1960s, the lift in organic matter from a 9 year grass ley was almost completely lost in the following three years of arable cropping.

So the path to ‘sustainability’ is strewn with conflicts. Should we convert three quarters of our arable land to leys for a temporary small increase in soil organic matter? Should an increased population of cattle and sheep be allowed to graze on these leys because of the inevitable rise in greenhouse gas production? Will the banning of sheep and cattle result in a significant decrease in the availability of organic manures to improve arable land? Would it be asking too much to ask for some clear holistic thinking on the issue of sustainability based on what is possible through best practice rather than listening to, often unrealistic, solutions to individual issues?