Intensive monocropping of maize is widely practised in densely populated regions of west Africa. A wide range of tillage systems are used for seedbed preparation without the benefits of research information from long-term experiments relating tillage method to soil properties. Soil chemical effects of eight tillage and residue management treatments were studied for 8 years or 16 consecutive maize monoculture crops for a western Nigerian soil with a coarse-textured surface horizon. Treatments established on a newly cleared land were: (1) notill ± crop residue mulch, (2) notill ± chiselling in the row zone at 50 cm depth, (3) mouldboard ploughing ± harrowing, (4) disc ploughing ± rotovation, (5) notill − residue mulch, (6) mouldboard ploughing at the end of rains or summer ploughing, (7) mouldboard ploughing ± residue mulch, and (8) mouldboard ploughing and harrowing ± ridging or ridge till.