Variation of root growth in a grass ley studied with a mesh bag technique [Agrostis capillaris, Phleum bertolonii, Holcus lanatus]

agrostis arena corte crecimiento croissance cutting desarrollo estacional essai fertilizantes nitrogenados grasslands growth herbage loam soils nitrogen fertilizers phleum poa pratensis praderas pruebas racine roots sable sand seasonal development sol sablolimoneux suelo franco trials