Evaluation of Locally-Sourced Liming Materials for Acid Soils in Akwa Ibom State, Southeastern Nigeria

A greenhouse experiment was conducted to evaluate the shells of molluscs, which are known to have high contents of calcium carbonate (CaCo ) and which are abundant in the coastal area of Akwa Ibom State, 3 for acid soils using yellow maize as test crop. The shells evaluated were those of snail (Achatina achatina), periwinkle (Turilella), clam (Cardium edule) and oyster (Spondylus spinosus). Commercial lime (CaCo ) was 3 included in the study to serve as a basis for comparison. Results indicated high neutralizing equivalent values of 89.4, 93.9, 92.8 and 87.6% for oyster (OY), snail (SN), clam (CL) and periwinkle (PR) compared to 96.0% for CaCo . Chemical composition of mollusc shells show high mean calcium (Ca) contents ranging from 337.1±14.7 3 in PR to 524.6±2.3gkg in CaCo ; magnesium (Mg) concentration was highest in CaCo (56.0±4.9gkg ) and 11 33 least in SN (22.8±6.4gkg ). The shells and CaCo when incubated with soil appreciably raised the soil pH, basic 1 3 nutrients (Ca, Mg, Fe), organic carbon, effective cation exchange capacity (ECEC) and percent base saturation (BS), but drastically reduced the exchange acidity. Available P level was also reduced probably a result of formation of insoluble Ca-phosphate and an increased soil pH. Results of incubating molluscs shells with soil revealed no significant differences (P 0.05) among the shells and CaCo since they produced almost the same 3 effect on maize plant height and dry matter yield, implying that any of the shells could be used to replace unavailable and sometimes unaffordable CaCo , to solve acidity problems of soils in Southeastern Nigeria. 3