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Influence of Clay Minerals on Some Soil Fertility Attributes: A Review

Open Journal of Soil Science 2019年第9期9卷 155-188页

作者： Georges kogge Kome roger kogge enang Fritz Oben Tabi Bernard Palmer Kfuban Yerima Department of Soil Science Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Republic of Cameroon

Clay minerals constitute an important component of the soil system and knowledge of their role in soil fertility is imperative for sustainable soil management and productivity. The aim of this work is to overview the influence of clay minerals on some major soil fertility attributes. The rationale for carrying out this work is that most soil fertility studies rarely incorporate soil mineralogy. Clay minerals, through their physical and chemical properties, affect soil fertility by controlling nutrient supplies and availability, through the sequestration and stabilization of soil organic matter, by controlling soil physical properties through microaggregate formation, by influencing soil acidity and controlling soil microbial population and activity. The main processes involved in these relationships are dissolution-precipitation and adsorption-desorption processes, alongside mechanisms involving the formation of short-range-ordered phases. Although the determination of soil mineralogical properties is very costly and time-consuming, information about a soil’s mineralogy is imperative for a holistic understanding and proper management of soil fertility. Therefore, the development of rapid, low-cost, reliable and efficient techniques of soil mineralogical analysis, directly applicable to soil fertility investigations, constitutes a major challenge. Also, future research should investigate the relationships between clay minerals and soil nitrogen vis-à-vis sequestration and stabilization. Lastly, clay minerals should be considered in studies dealing with soil quality assessment, especially in the choice of soil quality indicators.

关键词： Clay Mineralogy Nutrient Supply Ion Adsorption-Desorption Mineral Dissolution-Precipitation Nutrient Availability

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Short-Range-Order Minerals and Dominant Accessory Properties Controlling P Sorption in Tropical Tephra Soils of the Cameroon Volcanic Line

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Open Journal of Soil Science 2019年第8期9卷 113-139页

作者： roger kogge enang Bernard Palmer Kfuban Yerima Georges kogge Kome Eric van Ranst Soil Science Department Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon Geology Department Faculty of Sciences Ghent University Ghent Belgium

Knowledge on soil properties likely to influence P sorption in tephra soils is very important for sustainable management of available P. Sorption studies on six tephra soils were conducted to relate P sorption to soil characteristics in order to identify those with potential influence on P sorption. Four equilibrium-based sorption models commonly encountered in soil studies (Langmuir, Freundlich, Temkin, and Van Huay) were used to describe P sorption in the soils. P sorption was determined by measuring the residual P content of a clarified equilibrating solution of 0.02 N KCl containing varying concentrations (0, 5, 10, 15, 30, 40, 50, 60, 80, and 100 mg/L) of P as KH2PO4 after mixing with 1 g of soil in duplicates for 16 hours at 25°C. Maximum amount of P sorbed for the varying P concentrations used ranged from 2080 to 5402 mg/kg with a potential for greater P sorption maxima at higher P solution concentrations. P sorption in these soils was best described by the Langmuir and Freundlich models. Allophane and ferrihydrite are the principal species controlling the high P sorption in these soils. pH-NaF proved to be a potentially reliable test for assessing the presence of allophanic materials and thus for estimating P sorbed. This work would guide both effective and efficient P fertilizer management with economic implications for both the study area and similar environments.

关键词： Allophane Ferrihydrite Mount Kupe Mount Manengouba Sorption Isotherms

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Land Suitability Evaluation for Oil Palm (<i>Elaeis guineensis</i>Jacq.) in Coastal Plains of Southwest Cameroon

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Open Journal of Soil Science 2020年第7期10卷 257-273页

作者： Georges kogge Kome Fritz Oben Tabi roger kogge enang Francis Brice Tedou Silatsa Department of Soil Science Faculty of Agronomy and Agricultural Sciences (FASA) University of Dschang Dschang Republic of Cameroon

Declining yields in oil palm fresh fruit bunch (FFB) have been recorded over the past years in the coastal lowlands of southwest Cameroon and current actual yields are very low (−1•yr−1) compared to the potential yields (25 t FFB ha−1•yr−1). One of the problems limiting optimum oil palm production is lack of detailed pedological information to guide plantation establishment and management. A land suitability evaluation was carried out for some major oil palm producing areas of southwest Cameroon to identify land qualities limiting optimal production. Thirteen sites (9 with sedimentary parent materials and 4 with volcanic parent material) were evaluated using a parametric method. Results indicate that climate was not a major limiting factor for oil palm production in coastal plains of southwest Cameroon. However, soil physical characteristics (mainly clayey texture and poor drainage) and soil fertility constitute limitations to oil palm production. Specifically, limitations in cation exchange capacity (CEC), base saturation (BS), organic carbon (OC) and pH were slight to moderate while K mole fraction was the most severe and the most limiting in all the sites. The fertility limitations were more pronounced in soils derived from sedimentary parent materials where 33% had limitations caused by soil pH and OC compared to none for volcanic soils. In addition, 77.8% of sedimentary soils had limitations caused by CEC compared to 25% for volcanic soils. Considering the overall suitability, soils derived from volcanic parent materials were potentially more suitable for oil palm cultivation ((S3)—50%, (S2)—50%) compared to sedimentary soils ((N)—

关键词： Land Evaluation Oil Palm K Mole Fraction Soil Parent Material Coastal Plain Soils

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Germination and Early Seedling Growth of Moringa oleifera Lam with Different Seeds Soaking Time and Substrates at the Yongka Western Highlands Research Garden Park (YWHRGP) Nkwen-Bamenda, North-West Cameroon

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American Journal of Plant Sciences 2016年第15期7卷 2173-2185页

作者： Bernard Palmer Kfuban Yerima Grace Mbakpor Ayuk roger kogge enang Nicole Guehjung Yanick Alphonse Tiamgne Department of Soil Science University of Dschang Dschang Cameroon Department of Crop Production University of Dschang Dschang Cameroon Ministry of Agriculture and Rural Development West Region Cameroon

Moringa oleifera is a multipurpose tree used to remedy problems related to food insecurity and soil fertility degradation. Proper husbandry of this crop is contingent on the use of seedlings of good quality. This study aimed at assessing the germination and early seedling growth with different soaking durations and substrates composition. The seeds were obtained from the Far North region of Cameroon. A randomized complete block design with three replications was used. Two factors were tested;soaking duration with 4 treatment levels of 0 day, 4 days, 8 days and 12 days and substrates with 8 treatment levels: 100% soil, 75% soil + 25% poultry manure (PM), 50% soil + 50% PM, 25% soil + 75% PM, 100% sand, 75% sand + 25% PM, 50% sand + 50% PM and 25% sand + 75% PM. Germinated seeds and growth parameters were collected after every 5 days. The results showed that soaking duration and substrate composition influence germination and initial development of M. oleifera (p ≤ 0.05). At 25 days after soaking (DAS), soaking durations of 0 day (68.7%) and 8 days (53.1%) showed the highest germination percentages while seeds soaked for 12 days occupied the least position with 37.5%. At the same time, 75% soil + 25% PM (68.7%), 100% sand (64.5%) and 100% soil (60.5%) with the unsoaked seeds showed the highest germination percentages. The least germination percentages were represented by 50% sand + 50% PM and 25% sand + 75% PM with 35.5% and 27%, respectively. Unsoaked seeds with the substrates of 50% soil + 50% PM are the best practice for M. oleifera seedling production in the nursery.

关键词： Soaking Substrate Composition Germination Initial Growth Western Highlands

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Influence of Different Geomorphic Surfaces and Profile Modification on the Growth of <i>Maesopsis eminni</i>(Engl) at the Yongka Western Highlands Research Garden Park Nkwen-Bamenda, North West Cameroon

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American Journal of Plant Sciences 2017年第1期8卷 69-84页

作者： Bernard Palmer Kfuban Yerima roger kogge enang Claude Assembo Makem Nicole Guehjung Grace Mbakpor Ayuk Department of Soil Science University of Dschang Dschang Cameroon Ministry of Agriculture and Rural Development West Region Cameroon Department of Crop Production University of Dschang Dschang Cameroon

The growth of Maesopsis under the influence of various geomorphic surfaces was followed within a period of 70 months. Young plants of two months old were transplanted into 70 × 70 × 70 cm holes under natural conditions (no inputs such as manure and other amendments). A randomized complete block design was set up for the experiment, alongside a control, and growth parameters followed (height and collar circumference). Three blocks with different geomorphic surfaces were put in place for the experiment (upper slope or block 1, middle slope or block 2 and foot slope or block 3). Results of the experiment indicated that geomorphic surface had a significant effect on height but not on collar circumference. Plant height increased progressively from upper slope to foot slope;less tall trees were found at the upper slope, while the tallest trees were found at the foot slope. After 70 months, maximum average height attained by plants for the experiment was 1228.3 cm, observed in block 3 (foot slope), significant at 0.05 confidence level with respect to geomorphic surface. In blocks 1 and 2 (upper slope and middle slope), maximum average heights attained were 798.5 and 937.5 cm, respectively and were shown to be statistically equal at 0.05 confidence level. Geomorphic surface had no effect on collar circumference. Maximum average collar circumferences attained after 70 months were 62.8 cm (observed at the upper slope), 61.3 cm (observed at the middle slope) and 76.3 cm (observed at the foot slope) and the various collar circumferences were shown to be statistically the same at 0.05 confidence level. For the control, maximum height attained after 70 months was 1240 cm (observed at the foot slope). At the upper slope and middle slope, maximum average heights were respectively, 800 cm and 905 cm, and were statistically equal at the 0.05 confidence level but different from the foot slope value of 1240 cm. Maximum average collar circumference was observed at the foot slope (76.3 c

关键词： Maesopsis Upper Slope Middle Slope Foot Slope Height Collar Circumference Profile Modification Induced Hydrolysis

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Assessing and Mapping Land Suitability Units for Maize (Zea mays L) Production Using Integrated DEMATEL-ANP Model and GIS in the Foumbot Agricultural Basin (Cameroon Western Highlands)

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Journal of Geoscience and Environment Protection 2022年第6期10卷 57-85页

作者： Bertrand Kenzong Dieudonné Bitondo Primus Azinwi Tamfuh Georges Simplice Kouedeu Kameni Joseph Guepi Vounang roger kogge enang Emile Temgoua Dieudonné Bitom Department of Soil Science Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon Department of Mining and Mineral Engineering National Higher Polytechnic Institute University of Bamenda Bambili Cameroon

Land suitability assessment (LSA) is an essential step in the process of determining environmental limits for sustainable crop production. Up to date, studies on LSA for crop production in Cameroon have been based on empirical methods which are limited as they consider similar singnificance levels for all evaluation criteria and do not consider the interrelationships of criteria in the best-fit models. In the present study a qualitative land suitability evaluation by an integrated multi-criteria decision-making (MCDM) approach and geographic information system (GIS) was tested to assess and map suitable land units for maize (Zea mays L) production in Cameroon Western highland. Eight environmental criteria identified as the most relevant for maize production in the area of interest (AOI) saw their thematic maps prepared using ArcGIS 10.8. The relationship between criteria was considered by the DEMATEL method. The criteria were weighted using the ANP method. Thereafter, the land suitability map was obtained using the weighted overlay analysis (WOA) in ArcGIS. The results obtained indicated that slope has the highest specific weight and consequently the greatest influence on land suitability for maize production in the locality. The land suitability map generated showed that Foumbot’s agricultural land suitability for maize production varies from very high to marginally suitable (99% of the surface area). Specifically, 11% (8056 ha) is very highly suitable, 29% (21,119 ha) is highly suitable, 38% (27,405 ha) are moderately suitable and 20% (14,422 ha) are marginally suitable. The remaining 1% that falls under non suitable class represents 606 ha and is located on the steep slopes around the Mount Mbappit. The kappa analysis reveals a total overall accuracy of 78.67% and a kappa value of 0.7256 with an asymptotic error of 0.058 which is good. Then the model used in this research is highly recommended for future land evaluation works in Cameroon and similar ecosystems ar

关键词： Decision Making Trial Evaluation Laboratory Analytical Network Process Geographic Information System Land Evaluation Maize Weighted Overlay Analysis Foumbot Western Cameroon

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An Efficient Class of Calibration Ratio Estimators of Domain Mean in Survey Sampling

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Communications in Mathematics and Statistics 2020年第3期8卷 279-293页

作者： Ekaette I.enang Etebong P.Clement Department of Statistics University of CalabarCalabarNigeria Department of Mathematics and Statistics University of UyoUyoNigeria

This paper develops a new approach to domain estimation and proposes a new class of ratio estimators that is more efficient than the regression estimator and not depending on any optimality condition using the principle of calibration *** wellknown regression and ratio-type estimators are obtained and shown to be special members of the newclass of *** of analytical study showed that the new class of estimators is superior in both efficiency and biasedness to all related existing estimators under *** relative performances of the new class of estimators with a corresponding global estimator were evaluated through a simulation *** and evaluation are presented.

关键词： Auxiliary variable Calibration approach Efficiency Global estimator Ratio-type estimator Stratified sampling Study variable

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Empirical Studies on Topographical Influences on Crbc/Akbc Terrestrial Television Stations’ Signals in Akpabuyo Local Council Area, Nigeria

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Journal of Computer and Communications 2019年第9期7卷 50-71页

作者： Donatus enang Bassey Godwin O. Effiong Ofem U. Omini Effiong O. Obisung Electronics/Computer Technology Unit Faculty of Engineering University of Calabar Calabar Nigeria Electrical Engineering Department Cross River University of Technology Calabar Nigeria Physics Department Faculty of Physical Sciences University of Calabar Calabar Nigeria

Dissemination of information to citizens is a relevant component of governance. Expectedly, viewers tuned to broadcast stations within and outside their localities, expecting their receivers to faithfully reproduce the exact features of the transmitted signal. Akpabuyo is a dense forest zone near the creeks leading to the Atlantic ocean in Cross River State, Nigeria. The location has distinct environmental characteristics that made Akpabuyo Area Council, a challenging location to propagate electromagnetic waves;and therefore recipe for further investigation. Radio frequency analyzer, with 24 channels spectrum, ranging between 46 - 870 MHz (model: ***.R.-“DLM3-T”) was deployed to capture signals from terrestrial television stations (TV). CATV measured signal of TV stations in dB, dBμV and dBmV. Its frequency ranged from 40 - 860 MHz;while varying from channel 1 to channel 69. Measurements taken from Akpabuyo L.G.A. showed the following results: the signal strength received from VHF Channel 11 ranged from 20 dBμV to 49 dBμV. From recorded empirical statistics from the study, 50% of the area received signal from this station above 30 dBμV, while other regions had signals below this value;representing the fringe zone of the frequency. The results obtained from the study relatively showed acceptance with Egli’s model. The study recorded a steady fluctuation between 17 dBμV and 19 dBμV from both propagating stations. However, Channel 27 signal at 519 MHz, had very weak signal coverage in Akpabuyo Local Government Area;with signal strength dropped to as low as 13 dB in many parts of the rural area. The study discovered that the state’s broadcasting stations, both at UHF and VHF channels did not transmit successfully across this densely forest (rural) location. Remedial measures such as installing Repeater stations at different locations as signal booster were recommended.

关键词： Akamkpa Biase Broadcast Station Channels Propagation Models Signal Television Stations UHF/VHF Signals

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Factors Undermining the Investigation of Child Contacts of TB Patients： The Case of FCT, Abuja, Nigeria

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Journal of Health Science 2014年第3期2卷 152-156页

作者： Olajumoke Onazi Saddiq Abdurrahman Emmy Van der Grinten Moses Onazi enang Oyama Mustapha Gidado Amos Fadare Omoniyi TBCARE I Project M&E Unit Federal Capital Territory Abuja 930283 Nigeria Federal Capital Territory TB and Leprosy Control Program Federal Capital Territory Abuja 930283 Nigeria American Leprosy Missions Aburi M169 Ghana Research and Data Solutions Federal Capital Territory Abuja 930283 Nigeria WHO Office Abuja 930283 Nigeria

Facility records of 320 TB （tuberculosis） patients were examined over a one-year-period; January-December 2009 to ascertain the screening of children under 6 years of age who have had contacts with sputum smear positive TB patients as stipulated in the NTBLCP （National Tuberculosis and Leprosy Control Program） guidelines. In addition, semi-structured questionnaires were administered to 28 DOTS （directly-observed treatment strategy） clinicians to elicit information to help explain findings from the analysis of the routine data. Over 60% of children less than 6 years of age who had contacts with TB patients were not investigated in the health facilities included in the survey. The level of educational attainment of DOTS providers was associated with the screening of TB patients＇ contacts （P = 0.008）. Forgetfulness by clinicians to ask for or screen children of TB patients in the facilities is the singular most important factor undermining contact investigation. The proportion of under 6 years TB contacts screened or not screened for TB in the facilities was similar according to the age and gender of TB patients, and the type of health facilities where treatment was accessed by patients （P = 0.325）. The study underscored the need for the state program to evaluate the quality of service provision as well as counseling provided to TB patients at the facilities.

关键词： Contact investigation children contact tuberculosis TB patients case finding.

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Codiaeum Variegatum Hydro Alcoholic Leaf Extracts and Their Fractions Inhibit Pro-Inflammatory Mediators in Vitro

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Journal of Biosciences and Medicines 2023年第5期11卷 40-54页

作者： Sylvain Pechangou Nsangou Charifa Ngbetkom Mandou Carine Matsigang Fondjou Vigny Sayal Ngohoba Edie Brice enang II Ibrahim Njingou Emmanuel Mfotie Njoya Frederic Nico Njayou Paul Moundipa Fewou Laboratory of Pharmacology and Toxicology Department of Biochemistry Faculty of Sciences University of Yaounde1 Yaounde Cameroon Centre for Quality of Health and Living Faculty of Health and Environmental Sciences Central University of Technology Bloemfontein South Africa

Codiaeum variegatum has been widely investigated for its biological proprieties ranging from the antiamoebic potential to the phytochemical analysis. The aim of the present study was to evaluate the anti-inflammatory potential of C. variegatum leaf extracts and fractions. A primary macrophage culture activated by Saccharomyces cereviseae (SC) was used to evaluate cell cytotoxicity and anti-inflammatory potential of the plant extracts and fractions. Macrophages were treated with different concentrations (0.1;1;10 and 100 μg/mL) of the extracts/fractions for the inhibition of 5-lipoxygenase activity, nitric oxide (NO) and Tumor Necrosis Factor Alpha (TNF-α) production. No significant difference was observed on cell viability in the presence of extracts and fractions at tested concentration during the incubation period. Extracts and fractions of C. variegatum inhibited the 5-lipoxygenase activity, NO and TNF-α production by viable primary mouse macrophages in a concentration-dependent manner. The fractionation process increased anti-inflammatory activity. Among fractions, HEF2, HEF3, HEF5, EEF1, EEF3 and EEF5 exhibited the best anti-inflammatory potential. C. variegatum extracts and fractions exhibited a greater anti-inflammatory potential throughout the inhibition of pro-inflammatory mediators such as NO, 5-Lox and TNF-α.

关键词： C. variegatum Anti-Inflammatory 5-Lipoxygenase NO TNF-α

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