Adaptation of Sowing Techniques to Maintain Important Lumbricid Biomasses in the Hydromorphic Soils of Normandy

Abstract

Permanent pastures are occupying 10.5 million hectares (IFEN, 1996) and are only moderately productive. Sustained fertilization and judicious exploitation methods will allow to increase their output. In the Vieux Pin INRA domain (Le Pin-au-Haras, Orne), the production of a pastured prairie which had been monitored for fifteen years increased from 4.5 t DM/ha to 8 t DM/ha after they had been moderately fertilized. Resowing a degraded prairie or destroying one, or even establishing a maize crop, means that the soil must be ploughed to make a good seedbed. If the ploughing works of the soil have a negative effect on the lumbricid populations, is it possible to conceive sowing techniques which would preserve this food source which is so important to the fauna? Is it possible to obtain a high forage production without degradation of the soils while maintaining the soils’ bearing capacity and their feeding potential for game species in winter? What are the environmental impacts of the various technical crop management sequences on nitrate losses, on erosion and on the risks of diffuse pollutions? What is the influence of intensive forage practices on lumbricid populations?