18th Congress of the European Society for Agronomy

Combining methods to manage ryegrass with less herbicides in arable crops: key of success of the irrigated on-fam experiment Cap du Futur in the south of the Paris Basin (FR)

Not scheduled

15m

Les Dortoirs (1st floor) (The Couvent des Jacobins)

Poster Synergies between short- and long-term goals Poster session #1

Speaker

Clotilde Rouillon

Description

One of the major issues of cereal systems in the Paris Basin is the management of ryegrass (Lolium spp.). The emergence of herbicide resistance, the increase in winter crops instead of spring crops, and the ban and restrictions on the use of certain chemical molecules tend to exacerbate this problem. Weed management is therefore a short-term but also a long-term issue on which Arvalis, an applied research institute dedicated to arable crops, works on for several years. If the optimization of chemical interventions appears to be an essential lever in the short and medium term, the presence of herbicides in water forces us to find alternative solutions in the long term.

The “CAP du Futur” is an irrigated cropping system set up on the ARVALIS experimental platform in Boigneville (91) in 2016. This experiment at farm scale aims to find sustainable solutions to manage herbicide-resistant ryegrass infestations with less herbicides and without glyphosate while remaining profitable. A combination of levers is tested to achieve this goal with a systemic approach (Metais & al, 2018).

The alternation of winter and summer crops is a major lever for disturbing weeds. It drives to the following crop rotation: sunflower / winter wheat with a very high protein content/ winter wheat / grain maize / grain maize / spring barley / winter wheat. Because of a problem with local outlets, hemp was replaced in 2020 by a clover fallow and then by a sunflower.
Tillage is mobilized through the technic of false sowing and by ploughing. The use of herbicides is limited thanks to the use of mechanical weed control and spot spraying on maize and sunflower crops.
Arvalis has been testing technological innovations related to digital progress for many years (Desbourdes & al, 2020). As soon as these technologies demonstrate their benefits in weed management, they are integrated into CAP practices.

Methods developed by ARVALIS and proven over many years make it possible to extrapolate the technical results obtained on the experimental system with a size of 47 ha, to a farm of 300 ha for two assets. This extrapolation is made possible thanks to the SYSTERRE® tool (Casal & al, 2022).

The results on the period 2017-2023 show that ryegrass management is satisfying: less pressure while a reduction in herbicide use (Bouttet & al, 2023). The herbicide treatment frequency index is relatively low, with an average of 1.61 (local reference: 2.32). This index counts the number of reference doses used per hectare during a growing season. Except for hemp, yields and quality of the different crops are closed to the objectives. The economic sustainability of the system remains profitable. But the three years of hemp and the clover still impact the average margins. There is a difference of 166 €/ha between the net margin of CAP and the local reference (subsidies included).
Moreover, this system remains dependent on the use of certain active substances with uncertain futures. It was supplemented in 2020 by a piloted free-herbicide observatory to explore more disruptive solutions without economic constraint.

• Métais P., Bonin L., Perriot B., Desbourdes C., De Solan B. (2018) Gestion des adventices par l’agronomie et les agroéquipements : moyens mobilisables et perspectives. Colloque PHLOEME, 1ères Biennales de l’innovation céréalières, 24 et 25 janvier 2018.
• Desbourdes C., Perriot B. (2020). Innovations en désherbage : quatre techniques évaluées par les Digifermes d'Arvalis. Perspectives Agricoles, N°478, juin 2020, 66-71.
• Casal L., Berrodier M., Jouy L., Wissocq A. Rouillon C. 2022. SYSTERRE® : un outil d’évaluation de la multi performance des systèmes de culture aux multiples usages. Phloème 2022. 3 et 4 novembre 2022. Paris
• Bouttet D., Ménil A., Pègues A. (2023). Gestion durable du ray-grass : résultats d’un essai système irrigué grandes cultures du sud Bassin parisien. 25ème Conférence du COLUMA. Journées Internationales sur la Lutte contre les Mauvaises Herbes, Orléans, 5,6 et 7 décembre 2023. Végéphyl.