Evaluation of the fertility status of selected soils in Mbaise, Imo State southeastern Nigeria using nutrient index method

This study was carried out to evaluate the fertility status of soils in Ahiazu Mbaise, Imo State under three land use types using nutrient index method and fertility rating. Soil samples were collected from five sampling points each from three land use types at the depth of 0 – 20 cm. Samples were prepared and analysed for physical properties such as particle size distribution, bulk density, moisture content, total porosity and also soil chemical properties such as soil pH, organic carbon, total nitrogen, available phosphorus, exchangeable bases and base saturation . Data generated from laboratory analysis were subjected to statistical analysis. Results obtained showed that irrespective of the land use, soils of the study area were moderately acidic with high sand fraction (> 70%) resulting to poor physical condition such as poor moisture retention and total porosity. The chemical properties showed low organic matter content (15.8 – 29.1 g/kg), low total nitrogen (0.7 – 1.5 g/kg) and available phosphorus (3.1 – 5.6 mg/kg). The exchangeable bases were low and below the critical limits with predominant exchangeable H and Al. Soil nutrient depletion followed this order: fallow land > palm plantation > cassava cultivated land. Results also showed little variability in soil physicochemical properties in the three land use types. Results of the nutrient index and fertility rating also showed that soils of the study locations were extremely poor in fertility with a fertility rating of 1 and nutrient index of 1 in the three land uses signifying poor fertility status when compared to standard ratings. Therefore, to improve the quality and fertility level of soils in these locations, there is urgent need to adopt strategic management measures and agronomic principles that will improve the fertility levels.Keywords: Soil fertility, Nutrient index, Organic matter, land use, Ultiso

SPATIAL VARIABILITY OF SOIL PHYSICOCHEMICAL PROPERTIES AND HEAVY METAL CONCENTRATIONS IN OWERRI MUNICIPAL DUMPSITES

Heavy metals pose a serious threat to our environment due to the fact that majority of annual vegetable crops consumed by man and animal are produced from the polluted sites without knowing the level of it taken up by plant which revolves into food chain. This study evaluated the variability of soil physicochemical properties and heavy metals concentration in Owerri municipal dumpsites in Imo State. Samples were collected in three replicates 0, 5 and 10m away from refuge dumpsites at 0 - 30cm depth using soil auger in Ihiagwa, Avu, Abazu and Obinze. Samples were analyzed for soil properties and heavy metals-concentrations using standard methods. The concentrations of the studied heavy metals (Pb and Cr) were compared with the permissible limits of other countries. pH results from the analyzed sampled soils from the four locations were high (6.89, 6.80, 6.59 and 6.40) in Ihiagwa, Abazu, Obinze and Avu respectively while organic carbon followed the trend Ihiagwa>Avu>Abazu>Obinze. Organic carbon and total Nitrogen concentrations followed the same trend in Ihiagwa, Avu, Abazu and Obinze. Pb concentrations in the studied sites were above the standard limit recommended (0.05mg/kg) by Federal Environmental Protection Agency but within limit (100mg/kg) stipulated by European Commission. Nevertheless, Pb concentration was within the tolerance limit set by European Union but should be cautiously minimized to prevent health hazard on man and the environment. The use of refuge dumpsite for cultivation of arable crops should be avoided and lands on cultivation should be given a distance from the refuse sites