The homegarden agroforestry system of Bukoba district, North-Western Tanzania. 2. Constraints to farm productivity

agriculteur agricultores agroforesteria agroforesterie agroforestry coffea canephora constraints contrainte crop yield curculionidae domestic gardens exploitation agricole explotaciones agrarias farmers farms fertilidad del suelo huertos familiares jardin familial migration musa (bananas) musa (bananes) musa (bananos) nematodos de las plantas plant nematodes productividad productivity rendement des cultures rendimiento de cultivos soil fertility tanzania tanzanie