ARID ZONE JOURNAL OF ENGINEERING, TECHNOLOGY AND ENVIRONMENT

16-22

Authors: A M Kundiri, I Audu, A M Kundiri

Soil saturated hydraulic conductivity is an important parameter for flow and transport related processes in the soil but the different methods of its measurement vary under different field conditions. The performance of three in situ methods were evaluated at 20, 40 and 80 cm depths on an alluvial floodplain soil classified as fine loamy isohyperthermic aeric Trapaquept. TheGuelph permeameter method gave the lowest estimates of saturated hydraulic conductivity, possibly because of small sample size, whereas the Disk permeameter method gave maximum values for saturated saturated hydraulic conductivity with minimum variability, possibly due to large sample size. The estimates of saturated hydraulic conductivity were most comparable for the velocity permeameter and the laboratory method using a constant head permeameter.

31-36

Authors: A I Inegbenebor, A O Inegbenebor

As elemental contents of sheabutter play a vital role in various physiological and metabolical activities in the human body, it is necessary to compare the chemical contents of sheabutter extract from different procedures in order to identify the most important extraction procedure. Sheabutter extracted using a locally developed machine was compared with the composition of extract from two other techniques using a soxhlet extractor and the traditional procedure. The result shows increasing recoveries of most of the elements on progressing to the design machine and soxhlet apparatus from traditional procedure. The chemical analysis results showed the amount of lead, mercury, manganese, iron, copper, calcium, iodine, magnesium and phosphorus present in the sheabutter. The amounts of Ca, Fe and Pb are as high as 22.8 µgl-1. This work also found that the levels of elemental composition in the extracts of 22.8 µgl-1 sheabutter from modern machine are more than those from the traditional extracting method of 16.2 µgl-1. Possible reasons and implication of those findings are discussed.

45-50

Authors: B Umara, M Yaji, A Fannami

Groundwater quality was monitored in 10 wells in the proximity of solid and liquid waste disposal systems in Damaturu, Nigeria. In this study, nitrate, pH, electrical conductivity, turbidity, total dissolved solids, hardness, colour, iron, chloride, sulphate, fluoride and coliform count were examined in the laboratory using standard procedures. Closeness to pit latrines and septic tank resulted in significant concentrations of nitrate (28, 40 and 41 mgl-1 in wells 2, 8 and 9 respectively) which exceed the European Community Standards. Consumption of water with high nitrates above the permissible limit of 20 mgl-1 can cause methyglobenemia syndrome. Co-existence with waste disposal system resulted in high pH, iron and faecal contamination with average coliform density of 29 (100ml)-1 of sample exceeding the maximum permissible limit. Total coliform indicate pathogens that cause cholera, typhoid, dysentery, gastro-enteritis, diarrhea and so on. Excessive iron can impart colour and stimulate bacterial growth. The pH values normally exert influence on biological activity and may result in undesirable taste. The paper tries to offer some suggestions to the identified problems.

63-70

Authors: E Mamman, J O Ohu

A laboratory experiment was conducted to determine the influence of an organic material (groundnut haulms) on the compactibility and air permeability of three most common agricultural soils (clay, sandy clay and sandy loam) in Borno state. The organic material was incorporated into the soils at three levels (2, 4 and 6% by mass of dry soil) and the soil-organic matter mixtures were compacted at three levels (5, 15 and 25 hammer blows). Incorporation of the organic material into the soils reduced their bulk densities and increased their air permeabilities. The bulk density for Ngala town clay, Nguma sandy clay and University sandy loam soils when incorporated with 2% organic matter and compacted using 25 hammer blows at 10% moisture content were 1.50, 1.59 and 1.74 Mgm-3 respectively. When the organic matter level was increased to 6% and compacted at 10% moisture content using 25 hammer blows, the bulk densities of the soils reduced to 1.41, 1.49 and 1.63 Mgm-3 for Ngala town clay, Nguma sandy clay and University sandy loam respectively. The air permeability for Ngala town clay, Nguma sandy clay and University sandy loam soils when incorporated with 2% organic matter and compacted using 25 hammer blows at 25% moisture content were 17, 23 and 37 μm² respectively. When the organic matter level was increased to 6% and compacted at 25% moisture content using 25 hammer blows, the air permeability of the soils increased to 28, 32 and 48 μm² for Ngala town clay, Nguma sandy clay and University sandy loam, respectively. For each level of organic material, air permeability of each soil decreased with increase in the number of hammer blows. Incorporation of the organic material into the clay soil increased its susceptibility to compaction and this resulted in much lower values of air permeability than in the sandy loam soil. Statistical models were generated to predict the air permeability of the soils in terms of silt and clay contents, moisture content, compaction and organic material levels. The implications of the results obtained in determining severity of compaction on these agricultural soils were discussed.

78-88

Authors: I B Goni, W M Edmunds, F A Adeniji

Groundwater is the perennial source of water supply for domestic and other applications in the Nigerian sector of theChadbasin. Therefore, quantifying the current rate of recharge is fundamental to sustainable management of the resource. The chloride (Cl) mass balance technique was used to estimate the rate of recharge. Average Cl concentrations in rainfall from three stations over eight years were used as input data. Eight unsaturated zone Cl profiles were obtained and Cl concentrations in the groundwater were measured for over 400 samples from wells and boreholes. An average recharge rate of 41 mm per annum was estimated from the unsaturated zone profiles. The regional rate obtained using Cl concentrations in groundwater is slightly higher, estimated at 48 mm per ammum, which is attributable to other mechanisms of recharge such as river channels, pools, depressions and regional flow that bypass the unsaturated zone. The estimated recharge to the shallow groundwater in this region is considerable and can sustain present day abstractions. The observed decline in water table in recent years is largely due to reduced rainfall during the Sahel drought and consequent reduction in recharge, although human impacts are also identified as is common with most semi-arid areas of the world. Although the flood plains aquifers (fadamas) are probably fully recharged annually through river channels, caution must be exercised in introducing irrigation schemes. Any agricultural development should be preceded by detailed studies, so as to utilise the quantity of water that is recharged annually and must also adopt water saving techniques.