The effect of long-term application of different ways of soil cultivation on the productivity of crop rotations

beta vulgaris cereal crops cero-labranza chernozem chernozems clima climat climate crop yield cultivos de cereales essai fertilidad del suelo labranza medicago sativa meteorological observations pruebas rendement des cultures rendimiento de cultivos rotation culturale rotational cropping soil fertility tillage travail du sol trials zero tillage