Determinants of yield variation of organic cereals in productive agricultural areas

Context
Organic farming aims to make agriculture more sustainable, but its sustainability benefits may be offset by lower yields compared to conventional farming. Avenues to increase organic yields have been studied extensively, but there is a lack of research using integrated approaches that consider co-variation between different organic management practices within commercial farming systems. Moreover, organic farmers face diverse bio-physical constraints that experimental, plot-level studies, often fail to address in a system-level context.
Objective
Our aims were to highlight and utilise existing variation among organic farms to understand the factors that limit yields, considering the entire cropping system and its context. This included crop management, biophysical conditions and spatio-temporal context.
Methods
For 56 commercial organic farms in southern Sweden, we mapped between-farm variation in management and how it related to cereal yields. We obtained data on crop yield and management practices from farmers, conducted field measurements of crop performance, available nutrients, and pests, and retrieved data on farming context from public land-use databases. In a two-step approach we investigated how management practices affect yield through the observed field constraints.
Results and conclusions
There was considerable variation in management practices between organic farms, which is often overlooked. Variation in cereal yields was primarily related to nutrient application and, to some extent, weed management. Yields were also explained by factors affected by more long-term management or even beyond the control of the farmer, such as soil organic matter, soil texture and weather. We conclude that there is potential to increase organic cereal yields, but that this requires consideration of the whole management system and adaptations to local conditions by individual farmers.
Significance
The yield-differential between organic and conventional farming has been argued to be an Achille's heel for organic farming. This study shows a large between-farm variation in management practices and yields in organic crop production that can help realizing the organic yield potential at farm and field level, strengthening organic farming as a tool for agricultural sustainability.