Dry matter and nitrogen accumulation by three leguminous green manure species and the yield of a following wheat crop in an organic production system

abonos verdes absorption de substances nutritives agriculture biologique azote contenido de materia seca crop yield cubrimiento del suelo dry matter content engrais vert green manures medicago lupulina mulching nitrogen nutrient uptake organic agriculture paillage rendement des cultures rendimiento de cultivos trifolium pratense trifolium repens triticum aestivum