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Vue d'ensemble de parcelles de différentes variétés de céréales : catalogue variétal des blés tendres d'hiver et des orges. La Minière (Yvelines).. © INRA, FOUCHARD Marc

Innovative Agricultural Systems: System Experiments

Saint-Laurent-de-la-Prée: embracing biodiversity

The Saint-Laurent-de-la-Prée system experiment near La Rochelle in Charente-Maritime is a fine example of agroecology principles in practice. Operating for nearly four years, this mixed crop–livestock system located in the Charentais marshes seeks to produce crops and livestock (calves, weanlings, finished cattle) while also “producing” biodiversity.

The Saint-Laurent-de-la-Prée system experiment near La Rochelle in Charente-Maritime is a fine example of agroecology principles in practice. © NICOLAS Bertrand
The Saint-Laurent-de-la-Prée system experiment near La Rochelle in Charente-Maritime is a fine example of agroecology principles in practice. © NICOLAS Bertrand

Feeding cattle while protecting marsh birds

“For birds that nest in pastures in the spring, grass height is a key factor” says station manager Christophe Rossignol. For example, grass should ideally be less than 10 cm high for northern lapwings to nest and then between 10–15 cm to protect chicks after hatching. Bird species do not, however, all nest at the same time or need the same plant cover. To ensure the grass is low enough, cattle must be put in the fields quite early, in March, but not too early or the clay soil is too soft (non-bearing) and there is not sufficient grass to feed the cattle correctly. “We are able to manage all these constraints by using several pastures with different heights of grass and for different lengths of time” says Rossignol.

A diversified crop system grown on 50 ha supplements the cattle’s diet while reducing the need to purchase food supplements. In addition to winter wheat, sunflower, and triticale, the nine-year rotation includes protein crops like pea and horsebean as well as alfalfa for winter feed stocks or to cover the summer slump in years of grass shortfall.

 

Applying agroecology principles

“We are looking to make best use of the system’s natural features. Pastures, for example, support plant and animal biodiversity and can play a role in improving water quality by breaking down nitrates” says on-site environmental engineer, Daphné Durant. “Grass margins (5 ha) also play a special role. They act as reservoirs for beneficial organisms such as pollinators and insects like soil beetles that prey on slugs and aphids. The station is open to researchers who come to study other aspects of the system like marsh soil structure or aquatic and canalside biodiversity.”

 

Biodiversity indicators such as birds, insects, and plants are monitored on an ongoing basis each year.. © inra, Nathalie Lemaire
Biodiversity indicators such as birds, insects, and plants are monitored on an ongoing basis each year. © inra, Nathalie Lemaire

A step-by-step approach

Unlike the system experiments in Grignon and Dijon, Saint-Laurent-de-la-Prée follows a step-by-step approach like the one at Mirecourt. There is a continual evolution towards the qualitative objectives of improving biodiversity, improving water and soil quality, and increasing autonomy, particularly in terms of feed autonomy for the herds. Improvements to feed autonomy should come in 2013 with the addition of grain silos on the station. Biodiversity indicators such as birds, insects, and plants are monitored on an ongoing basis each year. The multicriteria evaluation also calls for the system’s economic output and workload to be assessed yearly.

See also Inra Magazine, No. 14, pages 10–11.

Contact(s)
Scientific contact(s):

Associated Division(s):
Science for Action and Development
Associated Centre(s):
Poitou-Charentes