SOIL SCIENCE AND LAND MANAGEMENT

This study was carried out on a 0.25 hectare land at the SLM Research Hub, University of Benin, Edo state where the soil was cha acterized, classified and evaluated for its suitability for the cultivation of Ginger (Zingiber officinale) and Cucumber (Cucumis sativus L.). The soil survey process was carried out with an intensive scale using the Rigid grid systematic survey method and a mapping unit was delineated in the study site. A pedon was sunk in the mapping unit, described appropriately and sa pled for analysis. The soil samples were analyzed using standard method procedures at the laboratory. Soils were classified using the USDA soil taxonomy, World Reference Base for soil resources (WRB) and the local Nigerian classification system based on Moss (1957) as updated by Ogunkunle (1983). The suitability of the soil for ginger and cucumber production was evaluated using both limitation and parametric method. The current and potential land suitability classes were assessed. The result showed that the textural class of the soil varied from Loamy Sand in the surface to Sandy Clay Loam in the subsoil while the structure ranged from fine sub-angular blocky to medium sub-angular blocky with a base saturation of 1.37-4.54% and pH level of 4.3-5.2. Sand fraction in the soil ranged from 72.9- 86.2%, Silt from 1.5-2.4% and clay from 11.4-25.6%. Taxonomically, the soil was classified , a Sandy Isohyperthermic Rhodic Kandiudult under the USDA Soil Taxonomy and as a Rhodic Lixisol (Loamic, Differentic, Ochric) under the WRB system. Locally, it was classified as the Orlu Series (Normal).

The research was carried out at the Faculty of Agriculture, University of Benin to investigate the availability of soil phosphorus resulting from microbial inoculation in an Ultisol with maize as the test crop. The experiment was laid out in a Randomized Complete Block Design (RCBD) in three replications comprising; T1 (control), T2 (NPK15:15:15) and T3 (NPK15:15:15 + Bacillus sp)., to give a total of nine experimental plots measuring 2.5m x2.5m used for the investigation. Results from the work showed a significant effect (P=0.05) of NPK + Bacillus sp on the grain yield (8.7g/18.75m2) of maize than that of the uninoculated treatments (7.7g/18.75m2- 6.6g/18.72m2); while no significant differences were observed in the plant parameters measured until week8 where the leaf area (509.0 cm3) of the inoculated plants (T3) was significantly better than the values observed for T1 (350.7 cm) and T2 (420.3cm) respectively.

Phosphorus (P) is an important element for plant growth and development, However, P availability is strongly influenced by pH in soils. Hence, this study aims at evaluating P sorption as influenced by pH. This study examined some physical and chemical properties of soil as well as in phosphorus sorption capacity at different pH levels. Soil samples were collected from orlu soil series in Nigeria Institute for Oil Palm Research (NIFOR). Some physical and chemical properties were analyzed using standard procedures in department of soil science and land management resources laboratory, university of Benin. while the influence of pH on sorption was determined by equilibrating the soils with P retention solution containing 1000 mg P L-1 as KH2PO4 adjusted to exactly pH 3.0, 4.6, 7.0 and 8.6 for 24 hours. The P remaining after equilibration was determined using colorimetrically by the nitric vanadomolybdate yellow method using the spectrophotometer at 466nm. The % P retention was calculated from the graph of absorbency against P retention of the standard solution.The result showed that some physical and chemical properties studied were within the normal range suitable for crop production. The result shows that % P sorption varied with depth and was strongly influenced by pH. The P sorption was least at the neutral pH range of 7.0 with a mean value of 12.90 and was highest at very low pH (pH 3) with a mean value of 26.50. It was also high at alkaline pH range (pH 8.6) with a mean value of 13.84 confirming the influence of pH on P sorption in line with several studies stated in literature All the data collected were subjected to statistical analysis using Analysis of Variance of GenStat Statistical Package and means were separated using Duncan Multiple Range Test of the same GenStat package. It is recommended that farmers in the study area should maintain a neutral pH to minimize P sorption.