Experimental comparison of the nature conservation value, productivity and ease of management of a conventional and a more species-rich grass ley

abonos agricultura de bajo insumo agriculture faible niveau intrants conduite des herbages conservation de la nature cutting frequency engrais fertilizers frecuencia de las cosechas grassland management grasslands harvesting frequency herbage land diversion leys lolium perenne low input agriculture manejo de praderas nature conservation pastizal sembrado phleum pratense pradera temporal praderas prairie artificielle prairie temporaire productividad productivity retrait des terres sown grasslands sown pastures trifolium repens