Organic phosphorus in some northern nigerian soils in relation to soil organic carbon and as influenced by parent rock and vegetation

The distribution of organic phosphorus in relation to soil organic matter and the influence of parent material and vegetation of organic P level was studied in a number of soil profiles in the northern half of Nigeria. There was a close relationship between soil organic carbon and organic phosphorus contents of these soils. The ratios of these two ingredients were all less than 200:1. This fact suggests that organic P is likely to be mineralised. The effect of parent rock on organic P contents was slight, but there was an indication that soil profiles on metamorphic parent rocks contained more organic phosphorus than those on sedimentary parent material. Vegetation had a great influence on organic P as shown by the relatively higher organic phosphorus contents of profiles from southern Guinea savanna and the lower contents of the Sudan vegetation zone. The profiles from impeded drainage sites (fadamas) were generally richer in organic phosphorus than were those from comparable vegetation zones on well drained sites.