EFFECTS OF NO-TILLAGE AND ALLEY CROPPING ON SOIL PROPERTIES AND CROP YIELDS IN A TYPIC KANDIUDULT OF SOUTHERN CAMEROON

The effects of no-tillage and alley cropping with Cassia spectabilis h edgerows on soil properties and crop yields in a Typic Kandiudult of t he humid forest zone of Central Africa were studied over the period 19 90-1992 in southern Cameroon. The experimental treatments were no-till age and hand tillage, both of which were either alley cropped with C. spectabilis hedgerows at interhedgerow spacings of 6 m or not alley cr opped (control). A maize + cassava intercrop was planted in all plots at the commencement of each growing season. No-tillage had no signific ant effects on soil physical properties except to decrease soil temper ature. In comparison to hand tillage, no-tillage increased soil organi c C and total N in both years and pH in 1991. Mean organic C and total N with no-tillage were 1.77% and 0.174%, respectively, whereas with h and tillage were 1.35% and 0.145%, respectively. No-tillage also resul ted in a greater proportion of C. spectabilis roots occurring in the t opsoil. Alley cropping caused significant reductions in dry season soi l temperature, surface seat formation and cassava root growth, and inc reases in exchangeable Ca, effective CEC and water infiltration compar ed with non-alley cropped controls. Infiltration rate at 2 h after com mencing measurements were greater by 75% with alley cropping. Lowest m aize cob and cassava tuber yields were observed when no-tillage was co mbined with alley cropping whereas highest yields occurred with no-til lage alone.