Constraints to the introduction of Medics in French Mediterranean farming systems
Jean-Marie Prosperi and Joëlle Ronfort
INRA SGAP Montpellier - Domaine de Melgueil. 34130 Mauguio. France
Sheep rearing is the dominant livestock industry and an old component of farming systems in French Mediterranean regions. Although it suffers from low productivity and rural decline, it represents the only way to maintain human activities in such marginal lands (1). The French Mediterranean zone, a large strip from 50 to 120km wide along the Mediterranean coast and the island Corsica, covers 12% of France (7 millions hectares). It receives mostly winter rains with an average annual rainfall of 700mm and is subject to dry summers. Mean temperatures are still colder than in other Mediterranean climates. While the perennial forage are well known and used in Mediterranean France, the potential of annual self-reseeding forage legumes has still to be explored for both intensive or extensive sheep rearing systems. A large number of species occur in native vegetation, but few of them are used (2).
For medics, Ley-farming could be the prominent farming system for European dry areas such as central Spain, but its interest is limited to France where annual rainfalls allow more sophisticated rotations with cereals. The use of medics as an annual spring forage legume - to produce hay in place of vetches or peas, or to graze them in mixtures with grasses or cereals - is yet another possibility, but only for intensive sheep production.
The best way to use medics in our country is by over-sowing them in rangelands or in degraded natural pastures to increase both forage production and improve quality. Animals fed on nitrogen-rich forage, such as medics, increase their consumption of ligneous vegetation. This increase in the consumption of ligneous allows, for example, a better control of bushes in fire-break areas. Several experiments have been conducted with sub-clovers and medics in forest areas in the South of France.
As non-agricultural uses, Medics and sub-clovers can also be inter-seeded in vineyards to control weeds development and to reduce soil erosion on slopping lands, or to limit nitrate and herbicide pollution in intensive fruit productions. Medics are also increasingly incorporated in mixtures sown to turn green the railways or highways slopes in Mediterranean part of France.
Besides the economic and human constraints attached with the low level of productivity of sheep rearing systems in the South of France, one of the main constraint is the availability of adapted materials. Our breeding activity aims at producing medic cultivars suited to these uses and adapted to our environment. To broaden the basis of the variability available, a large program of collections from western Mediterranean basin has been realized (3)(4). Some results of the agronomic evaluation of our core-collection of Medicago truncatula and comparison with performance of Australian cultivars will be discussed.
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