Which is better, conventional or organic agriculture?

Researchers writing in the journal Nature Sustainability state that life cycle assessment (LCA), one of the most common methods for assessing the environmental impacts of agriculture and food, often tends to overlook vital factors, such as biodiversity, soil quality, pesticide impacts and societal shifts. These oversights could lead to wrong conclusions on the merits of intensive and organic agriculture, the report reveals.

According to three researchers from France, Denmark and Sweden, the implementation of LCA is too simplistic, and misses the benefits of organic farming. Studies using LCA sometimes claim that organic agriculture is worse for the climate, because it has lower yields, and therefore uses more land to make up for this.

“We are worried that LCA gives too narrow a picture, and we risk making bad decisions politically and socially. When comparing organic and intensive farming, there are wider effects that the current approach does not adequately consider,” said Hayo van der Werf, from the French National Institute of Agricultural Research.

Biodiversity, for example, is important for the health and resilience of ecosystems. However, it is declining globally, with intensive agriculture shown to be one of the main drivers of negative trends such as insect and bird decline. Agriculture occupies more than one-third of global land area, so any links between biodiversity losses and agriculture are important.

“But our analysis shows that current LCA studies rarely factor in biodiversity, and consequently, they usually miss that wider benefit of organic agriculture. Earlier studies have already shown that organic fields support biodiversity levels approximately 30% higher than conventional fields,” said Marie Trydeman Knudsen from Aarhus University, Denmark.

Pesticide usage is another factor to consider; increasing pesticide usage has led to pesticide residues in the ground and in water and food, which can be harmful to human health, terrestrial and aquatic ecosystems, and causes biodiversity losses. Organic farming, meanwhile, precludes the use of synthetic pesticides, but few LCA studies account for these effects. Land degradation and lower soil quality resulting from unsustainable land management is also problematic, and is rarely measured in LCA studies, which also often overlook the benefits of organic farming practices such as varied crop rotation and the use of organic fertilisers. Researchers state that LCA generally assesses environmental impacts per kilogram of product, thereby favouring systems that may have lower impacts per kilogram, while having higher impacts per hectare of land.

“LCA simply looks at the overall yields. Of course, from that perspective, it’s true that intensive farming methods are indeed more effective. But this is not the whole story of the larger agroecosystem. A diverse landscape with smaller fields, hedgerows and a variety of crops gives other benefits — greater biodiversity, for example,” said Christel Cederberg of Chalmers University of Technology, Sweden.

LCA’s product-focused approach also fails to capture the subtleties of smaller, diverse systems which are more reliant on ecological processes, and adapted to local soil, climate and ecosystem characteristics. Researchers note that efforts are being made in this area, but more progress is needed.

“We often look at the effects at the global food chain level, but we need to be much better at considering the environmental effects at the local level,” Knudsen said.

Researchers argue that current LCA methodology and practice is not good enough to assess agroecological systems such as organic agriculture. It must be improved and integrated with other environmental tools to get a more balanced picture.

Image credit: Yen Strandqvist/Chalmers