Soil quality changes under continuous cropping for seventeen seasons of an alfisol in Western Nigeria

alfisols calidad cero-labranza continuous cropping cultivo continuo culture continue deterioro del suelo experimentation fertilidad del suelo labranza luvisol luvisoles luvisols mais maize nigeria quality saison seasons soil soil degradation soil deterioration soil fertility sol sol tropical sostenibilidad suelo suelo tropical sustainability tillage travail du sol tropical soils zero tillage