["Hornkiesel" - a plant treatment product in biodynamic farming on a quartz powder basis: Application of Hornkiesel in combination with plant tinctures]

agriculture biologique biopesticide biopesticides bioplaguicidas control de enfermedades disease control ecologia ecologie ecology encuestas evaluation exigence des plantes experimentation ferme pilote fertilisation fertilizer application fincas experimentales gestion du sol manejo del suelo necesidades de las plantas organic agriculture pilot farms piretrinas plant condition plant protection plant requirements plant response plantas plante plants protection des plantes pyrethrins respuesta de la planta soil management surveys