[Regional seminar on the question of fertilization and of the peasant revenue on the acid soils in the high altitudes of Rwanda]

acid soils amendement calcique analyse de sol conservation des sols constraints contrainte crop yield cultivation cultivo development projects engrais organique enmiendas calizas farm inputs fertilisation fertilizer application food production inorganic fertilizers insumos agricolas land productivity liming materials moyen de production agricole organic fertilizers pratique culturale production alimentaire productividad de la tierra proyectos de desarrollo rendement des cultures rendimiento de cultivos rwanda soil conservation soil testing sol acide