SOIL SCIENCE PROJECT TOPICS AND MATERIALS

Bentonites are clays rich in smectite whose properties such as crystal structure and size, cation exchange capacity (CEC), hydration and swelling, thixotropy, bonding capacity, impermeability, plasticity and tendency to react with organic compounds make them advantageous for a variety of applications. Smectites are 2:1 type of aluminosilicate having crystal lattice that consists of two dimensional layers where central octahedral sheet of alumina is fused to two external silicate layers. Isomorphic substitution within the layers generates negative charges that are counterbalanced by easily replaceable alkali or alkaline earth cations. These cations are defined as exchangeable cations. Forces holding the stacks together are relatively weak and the intercalation of small molecules between the layers is easy. Smectite can be rendered organophilic by exchanging the exchangeable cations with alkylammonium ions.

When our article was published (Sombroek et al. 1993) it was in the relative early days of concern about global warming (the IPCC had only been established a couple of years before in 1989). The Food and Agriculture Organization (FAO) of the United Nations had other priorities at the time, focusing on food security and technical and policy assistance to Ministries of Agriculture in developing nations. Wim Sombroek, who had a keen interest in environmental issues had just been appointed as new director for the Land and Water Division at FAO’s Headquarters in Rome, Italy. Before his arrival, the Land and Water Division had been known for their activities at field level in developing countries in assisting in soil surveys, establishing irrigation schemes and giving fertilizer advice. The division had also built up a solid reputation in applied research (crop water requirements), pure methodology development (the Framework for Land Evaluation), and global information products in the field of soils (The FAO/UNESCO Soil Map of the World). The previous director, Graham Higgins, had inspired the Agro-ecological Zones methodology that determined agricultural production potentials in the developing world. Wim Sombroek had started his career in FAO as a junior expert in a FAO/UNESCO team for forestry research and animal husbandry, based in Belem, Brazil. On the basis of this experience he prepared a PhD-thesis on ‘‘Amazon soils’’, a subject that would remain near his heart throughout hi

This research work involves the improvement of the engineering properties of laterite soil by stabilization with quarry dust on fines. The laterite used for this research work will be collected at Osogbo. The sample will be subjected to laboratory tests at the Civil Engineering Department Laboratory Futa, Akura and Osun State Ministry of Works and Transport, Osogbo. The tests will be carried out on both the natural sample and the improved sample and will include: moisture content, specific gravity, grain size distribution, Atterberg’s limits, compaction and California Bearing Ration (CBR) tests both before adding quarry dust and after adding a varying percentage and proportion of quarrying dust. The result of natural sample and improve sample indicate that it could be used to alter and make up for the deficiencies in the particles sizes. If the laterite thereby increasing the potential for use as base material. The result of moisture content is a decrease on the optimum moisture content for laterite cement mixture as the quarry dust content increases. This because the quantity of laterite that contains clayey particles, which requires water for the bonding action is reducing thereby needing less water for hardening . the result on consistency limits decrease in the consisting properties, quarry dust alter, the graduation of the laterite while cement is used to bind the mixture together, which in turn reduces the liquid limit, plastic limit, linear shrinkage of the resulting mixture.

When a compressive load is applied to a soil mass, the volume of the soil mass tends to reduce, due to reduction in its voids. This reduction in volume of a soil mass on application of a compressive stress can rather be placed either normally (laterally), or vertically or in both directions depending on how the soil mass is allowed to deform. When a vertical compression deformation is non-uniform it poses serious danger to the safety of structures and other civil engineering facilities, therefore there is need to study the compressibility properties of soil in Maryland.

The effect of crude oil contaminated soil on physical and biochemical properties of beans (phaseolus vulgaris) was investigated. Fifteen polythene pots with drainage holes at the bottom, each containing 10 kg of surface soil, were randomly placed on a table in the screenhouse in a factorial combination of five treatment levels (0.4%, 0.3%, 0.2%, 0.1% and 0% w/w) of crude oil and were designated P4, P3, P2, P1 and P0 respectively. Three seeds of beans per pot were planted. Growth parameters (plant height, stem girth, relative water content (RWC), and soluble protein content (SPC)) and antioxidant indices were determined in the beans over a period of nine weeks after planting (WAP). Results showed that growth of beans planted in contaminated soil was significantly lower (p<0.05) than that of control.