Investigations on the rationalization of heavy soil tillage

beta vulgaris bore boro boron caracteres de rendimiento chaulage cinc clay soils cobre compactage du sol composante de rendement consumo de energia copper crop yield cuivre cultivos de invierno cultivos de primavera culture d'hiver culture de printemps encalado energy consumption farmyard manure fosforo fumier labranza liming magnesio magnesium manganese manganeso mejora de suelos perfil del suelo ph del suelo ph du sol phosphore phosphorus potasio potassium profil du sol rendement des cultures rendimiento de cultivos rotation culturale rotational cropping soil chemicophysical properties soil compaction soil improvement soil organic matter soil ph soil profiles sol argileux spring crops suelo arcilloso tillage travail du sol trifolium pratense triticum aestivum vicia faba winter crops yield components zinc