Reduction of P fertilizer requirement using lime and Mucuna on high P-sorption soils of NW Cameroon

Soil acidity and high phosphorus (P) fixation are real problems in the Highlands of Central and Eastern Africa. Phosphatic fertilizers are imported and costly for the average farmer. We used lime and Mucuna green manure to reduce fertilizer P requirement of traditional food crops in NW Camcroon. Lime and phosphorus significantly improved stand count, root and stem weights as well as yields of maize (Zea mays L.), bean (Phaseolus spp.), and Irish potato (Solanum tuberosum L.) in three consecutive cropping seasons. Liming was most effective at low P rates and its effect on yield diminished with increasing P fertilization. Likewise, high P was unnecessary when lime was applied. Mucuna green manuring behaved similarly to liming and reduced maize P requirement by between 45 and 83%. Additionally, liming raised soil calcium (Ca), pH, effective cation exchange capacity (ECEC), and lowered exchangeable acidity (Al+H) as well as Al saturation. Consequently, maize and bean yields correlated positively (P