Nitrogen turnover on organic and conventional mixed farms

abonos agriculture biologique animal production azote carga ganadera conventional farming crop production dairy industry danemark denmark dinamarca engrais exigence des plantes exploitation agricole explotaciones agrarias farming farming systems farms fertilizers industria lechera losses losses from soil necesidades de las plantas nitrogen organic farming perte plant production plant requirements production animale recherche research stocking density stocking rate taux de charge