[Preliminary report : volume I : 1 allowance and exploitation of swamp soils 2 the ditch-digging for the soil conservation 3 the mixed croppings]

agroforesteria agroforesterie agroforestry amendement du sol asociaciones de agricultores association d'agriculteurs autosuffisance autosuficiencia bogs chaulage cultivo mixto earthmoving encalado enmiendas del suelo erosion control evaluation farmers associations farmyard manure fumier liming marais mixed cropping movimiento de tierras plant production recherche research rwanda soil amendments terrassement tremedal water management