Laboratory experimentation for the statistical derivation of equations for soil erosion modelling and soil conservation design.

Since Ellison (1947) described the process of erosion as comprising a) the detachment of soil particles from the soil mass by raindrop impact, b) detachment by runoff, c) the transport of the detached particles by raindrop impact, and d) transport by runoff, research has been directed into the mechanics of each of these four phases and how the phases might be linked together in the form of a soil erosion model, such as the Meyer-Wischmeier (1969) model. From a literature review, it became evident that in spite of this work, gaps in knowledge still exist and that i) most studies on soil erosion tend to lump the processes together; ii) whilst a considerable amount of investigation has been carried out on splash erosion, the other processes have received very little attention; iii) there is no explicit study on the effects of factor-interactions on the processes and the role of the laboratory as a place for studying interactions by controlling factors has not attracted much attention; iv) equipment and techniques for the separate evaluation of the detachment and transport of soil particles by overland flow are not available; and v) studies on the hydraulic characteristics of overland flow in relation to the detachment and transport of soil particles in such flows are scarce. This study was therefore specifically aimed at establishing a sounder research base for modelling the subprocesses and ultimate~ for soil conservation design b,y: i) evaluating separate~ each of the above subprocesses; ii) assessing the influence of the factors affecting the processes, particular~ their interactioDS; and iii) examining the hydraulics of soil particle detachment and transport by overland flow with and without rain. As a means to achieve these objectives, a factorial experiment vas set up in the laboratory to examine both the individual effects of rainfall intensity (50, 80, 110, 140 mm h- 1 ) , soil ~ (standard sand, ISIUld, clay loam and clay) and slope steep:1.8Ss (3.5, 7.0, 10.5 and 14.0 per cent) and their interactions on each of the above subprocesses. Additionally, the effects of four rates of runoff (1.0, 1.6, 2.2 and 2.8 ~min) on the hydraulic characteristics of flow such as velocity, depth, Reyuolds number, Froude number and friction factor were examined and used in characterizing the detachment and transport of soil particles in these flows. For each subprocess, these variables were replicated four times. Splash detachment and transport were determined by simulating rainfall from a nozzle simulator over a target soil placed in a rectangular soil tray (10 x 20 x 4 cm) which being set in the centre of a catching tray (90 x 80 x 30 cm) allows for the separate determination of ups lope and downslope splash. The separate measurement of the detachment and transport of soil particles by overland flow with and without rain was carried out b,y using a specially designed rainfall simulator - bed flume facility with runoff and sediment input and measuring devices. The results were analysed by analysis of variance to show the Significance of soil type, rainfall in tensi ty, flow rate t slope steepness and their first and second order interactions in influencing the processes studied. Multiple correlation techniques were used to search for the best associations between the erosion influencing variables and soil loss. RegreSSion analySis was used for establishing predictive equations for detachment and transport rates. Detachment of the test soils by splash can be placed in rank order of standard sand, sand, clay and clay loam with increasing resistance. For splash transport the order is standard sand ) clay > sand > clay loam. For each soil type there are significant increases in splash detachment and transport with increasing rain intensity and slope steepness. The most significant interactions influencing the two splash processes are soil x intensity and slope x intensity for detachment and transport respectivel,J. Significant interactions show that the factors are not independent of each other; the simple effects of a factor differ, and the magnitude of any simple effect varies according to the level of the other factors of the interaction term. The factors influencing detachment by flow without rain rank in ~ order of importance as soil type, slope steepness and discharge. The corresponding order for flow with rain is discharge, slope steepness and soil type. The order of soil detachability for both flow with and without rain is standard sand , sand ~ clay loam> clay. There are also significant increases in detachment rate as slope steepness and flow rate increase. It is further shown that the first and second order interactions of the above factors Significantly influence detachment by flow. On a relative basis, the second order interaction is small and the importance of the first order interactions can be placed in an increasing order of slope x soil, slope x discharge t and discharge x soil for flow without rain. For flow with rain, they rank as slope x soil, discharge x soil, and slope x discharge. The slope x soil interaction showed that as slope steepens the influence of each Boil on detachment rates increases with the proportionate increase being greater for sand and standard sand than for clay and clay loam. The slope x discharge interaction revealed significant increases in detachment rate for all slopes as discharge increased. The magnitude of the response is however greater at the lower than higher slopes. As slope steepness increases, detachment rates by flow with and without rain are also enhanced. The increase was proportionately more for the 1.0 and 1.6 J/min than 2.2 and 2.8 J/min flows. The Boil x discharge interactiC?n also indicated that, for flow without rain, detachability increases more for clay and clay loam than for the sand and standal'd sand as discharge increases. In the presence of rain however, the response of the soils did not differ much. Detachment by flow without rain is predominantly by rilling. In the presence of rain, detacbment rates by flow are increased about three fold and relatively even removal of soil particles from the eroding bed is characteristic. Raindrop impact thus appears to inhibit rill formation by overland flow especially on small slope steepnesses. There is a critical slope steepness at which both raindrop impact and overland flow contribute equally to total detachment. At slopes lower than the critical value, raindrop impact is the main detaching agent whilst flow predominates the detachment process at steeper slopes. The critical slope steepness is soil specific and decreases in the order of clay ~ clay loam ) sand ~ standard sand. The transport of soil particles by combined flow and rain is significantly influenced by soil type, slope steepness, flow rate and their first and second order interactions. Transport rates decreased in the order of sand > standard sand ) clay ) clay loam. Increases in discharge and slope steepness significantly increased transport capacity. For a discharge range of 1.0 - 2.8 l/min, transport capacity increased four fold. The most significant interaction that influences transport capacity is slope x soil. Where factors interact significantly, interpretation of results based solely on the main effects of the influencing factors m&1 result in loss of vital information and lead to wrong conclusions. For example, examination of the slope x soil interaction showed that at lower slopes (3.5 and 7.0 per cent) combined flow and rain has a greater transport capacity for the larger clay and clay loam aggregates than for the fine grains of sand and standard sand. This is obscured when effects are averaged over all the slopes as is the case when only main effects are considered

A psychrometric analysis of thermal comfort In low-rise office buildings in Ghana

A research project on the thermal performance of office buildings in Ghana was conducted and in the process, data loggers were used to record indoor environmental conditions over a period of 12 months in five office buildings. The temperature and relative humidity values recorded were analysed and plotted on psychrometric charts. The results of the study in 15 offices wereplaced in psychrometric charts which showed uncomfortable indoor environmental conditions. The reasons were high relative humidity values, although the temperatures in most of the cases were below 29°C. The impression gained during the observation period was that occupants hadadapted to high humidity levels and therefore found maximum humidity levels of 80% comfortable, provided temperature values did not exceed 29°C. This significant clue calls for further study and the adjustment of the comfort scale for the climatic context of Kumasi, Ghana

Response Of Three Forage Legumes To Soil Moisture Stress

Plants of Centrosema pubescens, Lablab purpureus and Stylosanthes guianensis grown sepa-rately in pots under green house conditions, were subjected to moisture stress conditions of 100, 75, 50, and 25% field capacity (FC) and the effect on plant growth characteristics assessed. Soil moisture stress significantly reduced plant height, shoot and root dry weights, particularly in Lablab and Stylosanthes. Root/shoot ratio on the other hand increased as soil moisture regime decreased. A change in moisture stress from 100 to 25 % FC reduced nodule numbers by 37, 19 and 9 % in Lablab, Stylosanthes and Centrosema respectively and decreased nitrogen fixed by 32, 9, and 0.4 % in Stylosanthes, Lablab and Centrosema respectively. The mean P content of the plants decreased with decreasing soil moisture content while, that of K increased as moisture stress increased. The overall plant performance pointed to Centrosema as a more favoured for-age plant for dry environments .Keywords: Crop productivity, legumes, food security, water use efficienc

Effects of tillage and cropping systems on yield and nitrogen fixation of cowpea intercropped with maize in northern Guinea savanna zone of Ghana

Published information is scanty on the response of crops in mixed cropping systems to the various tillage systems practised by farmers in the northern savanna zone of Ghana. A field experiment assessed the yield and nitrogen (N) fixation of cowpea (Vigna unguiculata (L.) Walp) intercropped with maize (Zea mays L.) on four different tillage systems at Nyankpala in the Northern Region of Ghana. The experiment was laid in a split-plot design with four replications. The main factor was tillage systems comprising conventional (Con), bullock plough (BP), hand hoe (HH) and zero tillage (ZT). The sub-factor was cropping systems (CRPSYT) which consisted of sole maize, sole cowpea, maize/cowpea inter-row cropping system, and bare fallow in 2000. The last-named was replaced by maize/cowpea intra-row cropping system in 2001. The results showed that Con and BP, which produced over 10 cm plough depth, significantly reduced soil bulk density that favoured significant (

On-Site Effects and Cost of Fertility Erosion from Five Small Reservoir Catchments in the Upper East Region of Ghana

A study was carried out in the Upper East Region of Ghana to assess the on-site effects and the cost of fertility erosion from five small reservoir catchments (Dua, Doba, Zebilla, Kumpalgogo and Bugri). The catchment soils and reservoir sediments were sampled and analyzed for their bulk density and nutrient content. The mean reduction in soil depth in the various catchments was 3.996±3.806 mm y-1 in the order of Kumpalgogo>Dua>Bugri>Zebilla>Doba. The corresponding decrease in the water holding capacity of the top 20 cm depth of the catchment soils ranged from 0.563 to 4.698 % per year. The percentage loss in the total nutrient stocks in the top 20 cm of the catchments as eroded sediment-bound nutrients ranged from 9.63 to 64.71, 7.87 to 56.83, 6.12 to 54.82, 1.26 to 40.14, 49.86 to 12.65, 16.84 to 72.07 for OC, N, P, K, Ca and Mg, respectively. The total amount of nutrient loss in kg ha-1 among the reservoirs ranged from 2383 to 19672 for OC, 153 to 3048 for N, 3.15 to 42.59 for P, 41 to 290 for K, 432 to 2158 for Ca, and 63 to 483 for Mg. The cost of N, P and K removed by erosion was calculated by the Replacement Cost Method. The total cost per year (GH¢ ha-1 y-1) of fertilizers (sulphate of ammonia, single superphosphate and muriate of potash) was 286.15 for Dua, 74.289 for Doba, 225.061 for Zebilla, 1119.997 for Kumpalgogo and 96.376 for Bugri. The study has amply shown that soil loss through erosion reduces top soil depth, nutrient stocks and the water holding capacity of catchment soils. This will adversely affect crop productivity if no control measures are implemented. This can also lead to land degradation

Intuitive eating is associated with weight and glucose control during pregnancy and in the early postpartum period in women with gestational diabetes mellitus (GDM): A clinical cohort study.

High pre-pregnancy weight and body mass index (BMI) increase the risk of gestational diabetes mellitus (GDM) and diabetes after pregnancy. To tackle weight and metabolic health problems, there is a need to investigate novel lifestyle approaches. Outside of pregnancy, higher adherence to intuitive eating (IE) is associated with lower BMI and improved glycemic control. This study investigated the association between IE and metabolic health during pregnancy and in the early postpartum period among women with GDM. Two-hundred and fourteen consecutive women aged ≥18, diagnosed with GDM between 2015 and 2017 and completed the "Eating for Physical rather than Emotional Reasons (EPR)" and "Reliance on Hunger and Satiety cues (RHSC) subscales" of the French Intuitive Eating Scale-2 (IES-2) questionnaire at the first GDM clinic visit were included in this study. Participants' mean age was 33.32 ± 5.20 years. Their weight and BMI before pregnancy were 68.18 ± 14.83 kg and 25.30 ± 5.19 kg/m <sup>2</sup> respectively. After adjusting for confounding variables, the cross-sectional analyses showed that the two subscales of IES-2 at the first GDM visit were associated with lower weight and BMI before pregnancy, and lower weight at the first GDM visit (β = -0.181 to -0.215, all p ≤ 0.008). In addition, the EPR subscale was associated with HbA1c and fasting plasma glucose at the first GDM visit (β = -0.170 and to -0.196; all p ≤ 0.016). In the longitudinal analyses, both subscales of IES-2 at first GDM visit were associated with lower weight at the end of pregnancy, BMI and fasting plasma glucose at 6-8 weeks postpartum (β = -0.143 to -0.218, all p ≤ 0.040) after adjusting for confounders. Increase adherence to IE could represent a novel approach to weight and glucose control during and after pregnancy in women with GDM

Microbiological quality evaluation of ready-to-eat mixed vegetable salad, food ingredients and some water samples from a restaurant in Accra: A case study

One serious threat to public health in both developed and developing countries is the microbial contamination of food. This problem poses a great challenge and consequently has economic implications. Causes of microbial contamination are diverse and these maybe natural, environmental, or technological. The microbiological quality of most readyto- eat foods is of great significance to human  health because they require minimal or no processing when consumed. The aim of this research was to investigate the microbiological quality of some ready-to-eat mixed vegetable salad foods, ingredients as well as the wash water samples of an urban restaurant located in Accra, Ghana. A total of thirty (30) samples categorized into mixed vegetable salads, foods and water obtained from an urban restaurant in the national capital of Ghana, Accra. They were analyzed at the microbiology laboratory and food microbiology  la  Loratories of School of Allied  Health Sciences (UHAS) and Council for Scientific and Industrial Research-Food Research Institute (CSIR-FRI), Ghana, respectively. Standard microbiological methods that are per International Organization for Standardization (ISO) Methods and Nordic Committee on Food Analysis Methods (NMKL) were used in determining the presence and levels of bacteria and fungi. Data obtained were transformed from standard to logarithmic forms and reported as mean+standard deviations. The aerobic plate countsamples ranged from 0- 4.73 log 10 CFU/g. E-coli counts also ranged between 0- 2.53 log 10 CFU, while Bacillus cereus counts were very low at 0-<10 log 10 CFU/g. Clostridium perfringens and Staphylococcus aureus counts were also very low ranging from 0- 1.0 log10 CFU/g. Enterobacteriaceae counts also ranged from 0- 1.90 log10 CFU/g. Molds and yeasts counts were generally low and ranged from  0- 2.48 log 10 CFU/g and 0- 1.0 log10 CFU/g, respectively. None of the samples tested contained Listeria monocytogenes and Salmonella spp. Fungal microbial loads were minimal given the quantities, and were deleterious to the health of consumers. The study revealed that the bacterial loads on mixed vegetable salads, ingredients and water samples used and served by an urban restaurant in Accra were within safe limits according to American Public Health Association (APHA) and International Commission for MicrobiologicalSpecifications for Foods (ICMSF) guidelines and, therefore, good for human consumption. Key words: Ready-to-eat, Salads, water, Vegetables, Restaurant, Ghana, Microbial contamination, Consumer safet

Chronic methylphenidate preferentially alters catecholamine protein targets in the parietal cortex and ventral striatum

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.The psychostimulant methylphenidate (MPH) is the primary drug treatment for attention deficit hyperactivity disorder (ADHD) in children. MPH is well known to acutely block the dopamine (DAT) and noradrenaline (NET) transporters. Its effect on additional catecholamine targets is however less known. This study was aimed at comparing the effects of acute (2 mg/kg, i.p.) and chronic (2 mg/kg twice daily for 2 weeks) MPH treatment to young rats on key catecholamine protein targets in brain regions implicated in the symptoms and treatment of ADHD. For this purpose, the density of DAT, NET, the vesicular monoamine transporter 2 (VMAT2), the rate limiting enzyme for catecholamine synthesis tyrosine hydroxylase (TH) and the dopamine D1 receptor were measured in frontal (FC), parietal cortex (PCx) and the dorsal (DS) and ventral (VS) striatum. The data demonstrate that the effects of MPH depend on duration of treatment and brain region investigated. With the exception of DAT in the VS our results indicate that chronic but not acute administration of MPH increases levels of DAT, NET, TH, VMAT2 and D1. These effects were further more prominent in the VS over DS and in the PCx compared to the FC. In addition, chronic MPH enhanced DAT levels in the left DS but not in right side. To summarize, this study shows new evidence that chronic MPH to young rats preferentially alters catecholamine targets in PCx and VS over DS and FC. The effect of chronic MPH to increase levels of DAT, NET and VMAT2 suggests that the drug might long-term loose some of its acute action to increase extracellular levels of dopamine and noradrenaline. In conclusion, these findings provide novel insights into the mechanism of action by MPH in the treatment of ADHD and further suggest that the long-term effectiveness of the stimulant drug could be limited

Impact of tillage and fertility management options on selected soil physical properties and sorghum yield

Water and soil fertility are the most limiting biophysical factors affecting crop production in semi-arid West Africa. . This study was conducted in Nadion (south Sudan zone of Burkina Faso) to assess the impact of tillage practices (no-till, tied ridging; ripping and conventional tillage) combined with soil fertility management options (compost, NPK + Urea, crop residues, Compost+ NPK + Urea and a control) on soil moisture content and sorghum yield. The soil moisture was monitored weekly using the Time Domain Reflectometer (TDR) method and the soil bulk density was evaluated 30 days after planting. Zero tillage increased the soil water storage capacity compared to the other tillage practices at 0-30 cm depth. Sorghum straw residues application improved soil water content by 20%. Conventional tillage decreased surface soil (0-10 cm) bulk density. Compost + NPK + Urea application increased sorghum yield by 74% over the control while, NPK + urea and compost increased sorghum grain yield by 50% and 29%, respectively relative to the control (no soil amendment). Conventional tillage led to decrease in yield compared to zero tillage after two years of experimentation. The zero tillage combined with compost, NPK and urea increased sorghum yield by 28% compared to tied-ridging regardless of the fertility management options. Zero tillage is a promising option for sorghum production in the South Sudan agro-ecological zone of Burkina Faso.Keywords: Bulk density, fertility management, sorghum yield, South Sudan zone, tillage, water conservation