Lisbeth Mogensen

Purpose: Despite its importance for climate change mitigation, soil organic carbon (SOC) is still insufficiently accounted for in cattle life cycle assessment (LCA) studies. Thus, this study evaluated how different methods for estimating SOC changes affect LCA results for mixed dairy systems with varying grassland proportions and durations. Methods: Two SOC modeling approaches (Petersen et al. (2013) and rCTOOL) were applied, along with two methods for estimating C inputs to soil: allometric functions and fixed belowground biomass coefficients. The analysis covered three Danish dairy farm types ( conventional low stocking , conventional high stocking , and organic ) and three grassland scenarios: current practice ( Now ), extended grass area and duration ( More ), and current grass proportion with longer duration ( Equal ). Results and discussion: Despite variation in the SOC changes estimates per hectare of farmland, the two SOC modeling approaches exhibited similar overall patterns. Using fixed belowground biomass coefficients resulted in higher SOC changes estimates than allometric functions, especially in organic systems, which had a higher proportion of grassland. Across all farms, scenarios, and modeling approaches, SOC changes contributed only modestly to climate impacts per kg energy-corrected milk (ECM) over a 100-year time horizon, largely due to the choice of initial SOC level. For conventional farms, More scenarios resulted in the lowest climate impacts per kg ECM, driven by positive effects on SOC changes and direct land use changes. For organic farms, the most favorable outcome was provided by the Equal scenario, which supported both farm productivity and SOC sequestration. Conclusions: Overall, the study underscores the need for improved methods for the estimation of C inputs when modeling SOC dynamics in LCA. The climate change implications of grassland management scenarios are particularly relevant for mixed dairy farms with rotational grasslands.

In recent years, interest in studying the climate and environmental impact of organic food has grown. Here, we compared the environmental impacts of organic and conventional food using data from 100 life cycle assessment studies. Most studies focused on climate impacts, with fewer addressing biodiversity loss and ecotoxicity. Findings revealed no significant differences in global warming, eutrophication potential, and energy use per mass unit. However, organic food showed lower global warming, eutrophication potential, and energy use per area unit, with higher land use. Additionally, organic farming showed lower potential for biodiversity loss and ecotoxicity. Challenges in life cycle assessment include evaluating biodiversity, toxicity, soil quality, and carbon changes. The choice of functional units influences results, highlighting the importance of considering multiple units in assessing organic food’s environmental footprint. This study emphasizes the necessity for comprehensive assessments at both product and diet levels to support informed decisions.

One of the staple foods in a healthy and sustainable diet is legumes. As such, new dietary guidelines around the globe now include higher intakes of legumes. For example, the most recent Danish dietary guidelines recommend a daily intake of 100 g of cooked legumes. This is, however, far from current intakes. The question is then, how should legumes be (or not be) designed to enable this grand dietary transition necessary to contribute to current global sustainability goals? One option has been to produce legume-based meat alternatives. But is this the only way to go? In this opinion, we debate this solution. We outline the processing, health and climate aspect of legume product consumption and argue that we do not have the right information to be able to appropriately design future legume-based foods. We conclude that processing must be part of the solution as we also need to replace red meat with legumes and re-design traditional meals to include legumes or legume products. Finally, to create the necessary lasting impact for planetary and population health, further dimensions such as food culture, equitability and affordability should also be in focus.