18th Congress of the European Society for Agronomy

Co-building organic agriculture expansion scenarios with increased nitrogen autonomy at territorial scale: the case of Morlaix communauté

Aug 28, 2024, 12:25 PM

15m

Salle 13 (1st floor) (The Couvent des Jacobins)

Oral Synergies between researchers, society and farmers On-farm changes to support agro-ecological transitions: co design

Speaker

Souhil Harchaoui (UMR SAS, INRAE, Institut Agro)

Description

1/ Introduction

Organic agriculture (OA) has been identified as key strategy in the European Green Deal to increase the agricultural area dedicated to OA from the current 10% to 25%. One of the key challenges to achieve this goal is the careful management and improved circularity of nutrients, particularly nitrogen, which is a limiting factor for the expansion of OA agri-food system¹. Recent papers suggest that focusing on the territorial or landscape level can effectively enhance agri-food system sustainability². Similarly, participatory modelling scenarios have shown promise in designing a more sustainable future for the agri-food system. However, existing frameworks lack the ability to assess the complementarity of OA and conventional agriculture within a territory. Here our analysis aims to co-build scenarios with local stakeholders to expand OA to 30% of total agricultural land. By incorporating insights from local stakeholders into a nitrogen budget model, we assess the consistency of two co-built OA expansion scenarios with increased nitrogen autonomy.

2/ Materials, methods

The study focused on Morlaix Communauté district, a high livestock intensive district in Brittany covering 39 772 ha with 10% OA. Our research was conducted in four steps adapted from the participatory design agroecological pathways methodology designed by ref. ⁴ (Fig. 1). The first step involved assessing the current nitrogen flows of OA by calibrating the ALPHA N-budget model5 using regional agricultural statistics on agricultural productions and land use. Steps 2 and 3 consisted of scenario workshops with 20 territorial stakeholders divided in two groups (representing a wide range of perspectives including dairy, poultry and vegetable farmers, local officials, OA feed producers and water management entities) aiming to reach 30% OA. In steps 3 and 4, we translated qualitative drivers from the stakeholders in quantitative drivers based on existing literature and applied these values in the two scenarios.

Fig 1. Four-step process for participatory modeling of organic agriculture (OA) expansion scenarios (adapted from ref.4)

3/ Results

Our analysis highlights that current OA nitrogen autonomy in Morlaix Communauté stands at only 56%. The territory produces close to 34 kgN·ha-1·yr-1 with 60% of animal products. The main N input is biological nitrogen fixation accounting for 41%., followed by conventional manure for 34%, imported feed for 13%, and atmospheric deposition at 12%. Overall nitrogen use efficiency of OA is around 40%. During the workshops, local stakeholders listed nearly 100 levers to increase OA in the territory. Two third of cited levers primarily address economic and social changes with a significant focus on land use changes and current scattered parcels. The remaining third of these levels enhanced its nitrogen autonomy in case of expansion. These latter levers were used to develop two main scenarios that focus on variations in OA crop and livestock mix, the incorporation of legume crops and the level of integration of crop and livestock mix. These factors all contribute to the circularity of nitrogen in the territory.

4/ Discussion

In both OA expansion scenarios, contrasting pathways are observed to achieve increased nitrogen autonomy levels of 60 and 70%. Livestock plays a pivotal role in these scenarios by effectively balancing nitrogen flows within the system, especially through the use of manure to fertilize OA crops. However, there is a critical contextualized trade-off to consider regarding the livestock density threshold and nitrogen autonomy. We provide concrete examples of agri-food systems scenario transition co-developed with local stakeholders emphasizing the potential enhancements through the integrating other environmental dimensions such as the energy functioning of OA, or phosphorus and carbon flows.

5/ References

1. Barbieri, P. et al. Global option space for organic agriculture is delimited by nitrogen availability. Nat. Food 2, 363–372 (2021).
2. Koppelmäki, K. et al. Nested circularity in food systems: A Nordic case study on connecting biomass, nutrient and energy flows from field scale to continent. Resour. Conserv. Recycl. 164, 105218 (2021).
3. Van Der Wiel, B. Z. et al. Participatory modelling of scenarios to restore nitrogen cycles in a nutrient-saturated area. Sci. Total Environ. 170335 (2024)
4. Duru, M., et al. M. Designing agroecological transitions; A review. Agron. Sustain. Dev. 35, 1237–1257 (2015).
5. Chatzimpiros, P. & Harchaoui, S. Sevenfold variation in global feeding capacity depends on diets, land use and nitrogen management. Nat. Food (2023)