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GOALS

Maize is a particularly important crop in France and in the south-west. Irrigated maize monoculture systems are nevertheless being questioned (high pressure on water resources, risks for water and soil quality). Its long-term performance in a context of climate change is also threatened (water and heat stress). Consequently, it is necessary to develop new cropping systems, adapted to a context of climate change, that are economically competitive, environmentally sustainable and socially just.

The main objectives of the VACCARM (Vulnerability Assessment in Climate Change context of AgRoecological Maize cropping systems) project were to develop, test and evaluate climate-resilient maize cropping systems. To this end, VACCARM sought to answer the following questions:

• To what extent can the introduction of agroecological practices contribute to the participatory design of maize cropping systems that are a priori adapted to climate change (WP1)?
• What indicators can be used to assess the performance of these agroecological maize cropping systems in the context of climate change, at the plot and farm levels (WP2)?
• What are the performances (simulated or measured) of these agroecological maize production systems in a constrained climatic context (reduced water availability, changes in rainfall and temperature, etc.) (WP3)?

A recognised methodology and a promising evaluation tool

The VACCARM project has enabled the development and implementation of a simple, transferable and appreciated co-design methodology. Twelve cropping systems were redesigned, exploring a wide gradient of agronomic levers (introduction of intermediate crops, reduced tillage, mechanical weeding, population maize, etc.) compatible with climate issues. The environmental performance of these redesigned systems is improved on various points (water quality, organic matter, GHG emissions and energy consumption). Economic performance is more variable and must be analysed on a case-by-case basis. They will be linked to the margin squeeze between input prices, maize prices and the price of diversification crops.

The evaluation tool integrating the concept of vulnerability is still being developed. However, significant progress has been made showing the great variability of criteria used by farmers to assess their vulnerability to climate change and the need for an evolving tool. The surveys carried out have also shown that, beyond the classic explanatory factors (material, structural), cognitive resources (assistance and reactivity, perception of risk) also play a very important role in the decision-making process (in particular here the decision to start irrigation and the choice of evaluation criteria).

Raising awareness of agro-ecological practices among farmers

It is possible to grow maize in more "agroecological" cropping systems that are less vulnerable to climate change: by adapting to the material, soil and climate constraints, but also to the cognitive constraints of maize farmers. These systems have very impressive environmental performances. Quantitative (irrigation) and qualitative (herbicides) water management, as well as the management of nitrogen fertilisation (fertiliser, organic matter) are major points to be mastered.

In order to assess the vulnerability of farms to climate change, it is necessary to think not of a single set of indicators, but of a panel of criteria that can be adapted to particular contexts and to take into account all of its resources (structural, material and cognitive).

It is necessary to continue to raise awareness among agricultural actors. This cannot be done without the support of agricultural development organisations.