Mass of harvest residues and humus content depending on different cultivation systems on medium soil

barley cebada cero-labranza conventional tillage crop residues cropping systems cultivos de invierno cultivos de primavera culture d'hiver culture de printemps direct sowing faba beans field experimentation haba humus labranza convencional orge peso poids poland pologne polonia residuos de cosechas semis direct siembra directa sistemas de cultivo soil soil texture sol spring crops statistical methods suelo textura del suelo texture du sol travail du sol conventionnel trigo weight wheats winter crops zero tillage