Tailored management of organic dairy crop rotations to reduce carbon footprint and improve soil health

The agricultural sector plays a key role in the green transition. Organic dairy crop rotations, characterized by a high proportion of grass-clover in the rotation, grazing and the use of animal manure, have a significant potential to mitigate climate change by sequestering soil carbon (C), and simultaneously fostering soil health and functionality. The aim of the SoilHeal project is to identify and quantify the effects of management regimes in organic dairy crop rotations that increase soil C storage while improving soil health and reducing N losses.

The long-term organic dairy crop rotations experiment initiated at AU-Viborg in 1987 will be used for this purpose. This research platform provides a unique opportunity to quantify the effects of grassland share in the rotation and cattle manure on C sequestration and soil health - effects that otherwise cannot be reliably assessed because changes in soil C occur slowly but continue over long time periods. The focus will be on key indicators of soil health, including readily applicable soil structural stability analyses and advanced X-ray Micro-Computed Tomography (CT) scanning of soil. In addition, N leaching and N use efficiency within the cropping systems will be quantified. The refined estimates of C storage and N use, based on the results of the organic dairy crop rotations experiment, will be implemented in existing climate models, ensuring an improved and more accurate carbon footprint of organic dairy production. Throughout the project period, we will involve organic dairy farmers with the purpose of calculating the carbon footprint at farm level using the improved carbon footprint tool. Soil health indicators will also be measured at field level on their farms.

The project will result in the identification of management regimes that have positive climate and environmental impacts. Thus, the project can lead to a significant reduction in CO2-emissions and a reduction in N leaching in organic dairy crop rotations. Measurements of soil structure will provide greater insight into the development of a healthy soil and thus resilience to extreme weather events induced by climate change. Quantifying the climate change mitigation benefits of the management practices will enable reliable climate accounting, not only for the individual farmers, but also for the organic sector as a whole. The project will thus contribute to ensuring that organic dairy farming continues to play a key role in the green transition of the agricultural sector.