Benchmark surveys of three crops in Nigeria: wheat, millet, sorghum (conducted as part of the Nigerian National Accelerated Food Production Project)

abonos agriculteur agricultores cereal crops cultivos de cereales cultural methods encuestas sobre explotaciones engrais farm size farm surveys farmers fertilizers labour mijos millet millets mode de culture plant production rendement rendimiento sorghum taille de l'exploitation agricole trabajo travail trigo wheats yields