Regional super, international but a disaster? This could be the summary of a new study on organic farming published by British researchers in the journal Nature Communications (Smith et al., 2019). They have calculated a scenario in which England and Wales would switch to 100 percent organic farming. Their result: not only up to 40 percent less income could be the result. Also, food imports would increase, agricultural land would expand abroad, and at the end of the bill, domestic organic farming would even produce more greenhouse gases, such as carbon dioxide (CO2), than predominantly conventional agriculture.

The study is a kind of thought experiment to highlight the effects of certain factors. The four authors do not refer to it in the whole area of ​​Great Britain, because the data for England and Wales were more extensive. And they start from an unrealistic starting situation: the complete country-wide restructuring of agriculture and the simple assumption that the people in England and Wales continue to feed themselves as they do today. Only one decisive factor among others.

Organic farming usually has the advantage

In general, organic farming performs better in many areas than conventional land-based farming. In particular, when it comes to keeping soil fertile in the long term, to build up nutrients or to avoid harmful effects of artificial fertilizer as much as possible.

In terms of emissions of greenhouse gases - the aspect that the current study primarily considers - organic farming would have the advantage, at least regionally: in England and Wales, the organic cultivation of grain, fruit and vegetables would reduce emissions by a good 20 percent , the output from livestock husbandry would go back by about four percent. But the price for it, argue the British researchers, would be a loss of crop yields, so food would have to be imported from abroad to make up for it. The authors of the study estimate that up to five times more land would be needed worldwide to satisfy the current demand and nutrition of the Welsh and English population. All this would have climate damaging consequences through additional transport routes and conventional land use abroad.

"Although organic farming undoubtedly has local environmental benefits, such as carbon storage in the soil, lower pesticide loading and improved biodiversity, we have to offset this against the demand for increased production elsewhere," said Guy Kirk, one of the study authors, in a press release Cranfield University. His colleague and study leader Laurence Smith emphasized that, in particular, the potential effect on land use must be taken into account: "A net reduction in greenhouse gases could only be achieved if accompanied by a significant increase in bio-crops or a major change in national diets. "

Especially little steak, roast and sausage, more greens and nuts - that would be part of a human and environmental sensible diet. This year, physicians introduced it to Lancet magazine (The Lancet: Willett et al., 2019). The so-called planetary diet protects the health of individuals as well as nature and climate.

By contrast, the current study did not consider this aspect any further. Nevertheless, Stefan Frank from the International Institute for Applied System Analysis in Austria considers it an "interesting 'what-if-if' '. He told the Science Media Center (SMC) in Germany ( see box ). While the assumptions on agriculture in England and Wales are detailed, researchers have chosen "a very simplified method of calculation for greenhouse gas emissions". He therefore considers the study authors' conclusion that emissions saved in their own country would be neutralized by more land use abroad and that even more greenhouse gases would be released into the atmosphere on the balance sheet is less well documented.

In addition, the question arises as to whether lower yields in organic farming could be compensated for without large areas having to be tilled elsewhere. "At present, about 25 to 30 percent of the world's agricultural products are not in the stomach of consumers," explains Frank. They are lost, for example through crop losses and food waste. According to experts, in the EU, more than half of all discarded food ends up in private households in the bin. Klaus Butterbach-Bahl of the Karlsruhe Institute of Technology reported to the SMC that lower yields in organic farming and food waste could theoretically cancel out. Ultimately, it would be "illusory to assume that no more food is thrown away," said the expert in biogeochemical processes.