The development of agriculture has paved the way for modern society, where many people take it for granted that they will have enough food to eat every day. At the same time, agriculture has significant negative impacts on the environment, including nutrient leakage, spread of pollution and greenhouse gas emissions. In addition, the rise of modern agriculture has led to major changes in land use around the world, resulting in widespread loss of biodiversity.
Organic farming can help reduce many of the negative environmental impacts of agriculture, but on the other hand it has lower yields and therefore produces less food from the same area compared to conventional farming.
In her thesis "Developing organic farming - Agroecological challenges for sustainable intensification", Melanie Karlsson, a PhD student at the Centre for Environmental and Climate Science (CEC) at Lund University, together with colleagues from Lund University, SLU and Agrifood, has taken a broad and interdisciplinary approach to the challenges of organic farming. By investigating whether organic yields can be increased while maintaining the environmental benefits of organic farming, the research team has sought to identify the potential for organic farming to develop on a larger scale.
Large differences between organic farms
The studies focused on farms in southern Sweden, mainly growing winter wheat, spring barley, oats and winter oilseed rape. Using a variety of methods, including experiments, an extensive survey of farmers, field studies and interviews, the researchers have shown that organic yields are on average lower than conventional yields, but that the yield difference is smaller than previously thought.
"One explanation is that organic fields are more often found on less fertile land than conventional fields. When this is taken into account, the average yield difference decreases," says Melanie Karlsson.
The researchers also made another interesting discovery.
"We have seen that there is a bigger difference than one might think between the best and worst yields on different organic farms - which suggests that there is great potential to increase yields on many organic fields," continues Melanie Karlsson.
She believes that society often has a naive image of organic farming, which is often simplified to mean, for example, replacing synthetic fertilisers with manure and herbicides with mechanical weed control. When in fact there is almost as much variation in management practices as there are organic farms. Practices are driven by circumstances such as the farmer's own interests and time, or external uncertainties such as weather and demand.
So there is potential to increase yields on organic farms - both by locating them on more productive land and by finding the most efficient management practices. At the same time, new management practices on a larger scale can bring other challenges.
Risks to biodiversity important to consider
Several of the studies carried out have shown that the main factors determining the size of organic yields are nutrient supply, weed problems and growing conditions.
To increase nutrient supply, the availability of organic fertilisers needs to be increased and more nitrogen-fixing crops need to be grown. If nutrient inputs are increased, it is important that it all benefits the crop, otherwise nutrient loss, eutrophication and increased greenhouse gas emissions can occur. There is therefore a fine balance between how much nutrient is environmentally beneficial to add.
Organic yields are also limited by the amount of weeds; they compete with the crop for nutrients, light, space and water. However, the studies show that this is not always the case, and sometimes the crops and weeds can coexist without yield loss. At the same time, weeds are an important part of the biodiversity of the agricultural landscape and their flowers can, for example, benefit pollinating hoverflies, so it is not always desirable or necessary to remove the weeds completely.
"A more sustainable option is to try to make the crop more competitive through tailored management and choice of crop variety. And to encourage a weed community with many different species, where the bad weeds do not dominate. Then the weeds would not damage the crop as much and could instead contribute to biodiversity," says Melanie.
Hoping to help reduce polarisation
Although the four studies that make up Melanie's thesis are comprehensive, they only scratch the surface. For example, studies with longer time horizons, on a larger geographical scale, on more crops and on crop quality are needed. In addition, global warming and extreme weather pose additional challenges to all types of food production, and Melanie herself has a telling anecdote from her research:
"In one of the studies, we were supposed to work with an autumn-sown crop. However, there was an incredible amount of rain that autumn, which meant that the farmer was unable to sow his crop. We had to change our plans and work with a spring crop instead. It really shows the difficulties that can arise and the need for cropping systems that are flexible and work in a changing climate."
Finally, Melanie Karlsson hopes that her research will help to reduce the polarisation in the conflict between organic and conventional farming:
"The challenges of organic farming and whether it can work at large scale is a big question. But relatively little is said about its development potential. By highlighting the potential for increased organic production and how we can manage the risks involved, we can help to demonstrate a willingness to improve and work together towards more sustainable food production, in both conventional and organic farming."
Further information
Melanie Karlsson's research is part of a larger research project funded by Formas and is a collaboration between Lund University, SLU and Agrifood:
Constraints on organic farming – cec.lu.se
Here you can read Melanie's thesis in full:
Developing organic farming : Agroecological challenges for sustainable intensification | Lund University
