Research Outputs

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A bibliometric review of vegetation response to climate change
(Springer, 2021-10-25) Afuye, Gbenga Abayomi ; Kalumba, Ahmed Mukalazi ; Busayo, Emmanuel Tolulope ; Orimoloye, Israel Ropo
Global assessment of vegetation response to climate change (VRCC) studies was conducted to reveal the research evolution, current research hotspots and better understanding of dominant themes in VRCC areas of research from 1992 to 2019 through the use of bibliometrics. A total of 186 articles with the search term “Vegetation response to Climate change” were retrieved using the Web of Science (WOS) database. The annual growth rate of 10.3% connotes that research on VRCC has been increasing over time during the survey period. Average citations per article experienced many fluctuations over the years rather than maintaining the same growth rate, which connotes that this field of research reached was unstable in terms of average total citation per document. Results show that China ranked first followed by the USA and the UK, and this shows the dominance of these countries on VRCC studies over the years in review. Results from corresponding authors’ nationalities show that multiplecountry publications are relatively low compared to articles from single-country publications which showed a dominant trend. Hence, we can infer that most studies on VRCC were sustained by single-country publications. Results from this study revealed top-cited articles, the top global distribution of documents, academic collaboration, most relevant keywords and Word TreeMap of high-frequency keywords. The findings of this study show that “temperature” is in a central position in all keywords with the largest significant appearance in the field. In conclusion, the findings from this study may be applicable for planning and managing vegetation and forest ecosystem research and provide hints for future development.
A record of a melanistic rusty-spotted genet (Genetta maculata) from Lake Naivasha, Kenya
(African Journal of Wildlife Research, 2022-07-08) Do Linh San E.; Craig W.; Parker D.
A tale of two African mongooses (Carnivora: Herpestidae): differing genetic diversity and geographical structure across a continent
(Springer, 2022-10-13) Veron, Géraldine; Daniel, Caroline; Pagani, Paolo; Do Linh San, Emmanuel; Kitchener, Andrew C.; Hassanin, Alexandre
Phylogeographies of African mammals reveal patterns that correlate with Pleistocene environmental fluctuations and geographical barriers, which may affect species differently according to their habitat preferences and dispersal capabilities. The marsh mongoose Atilax paludinosus, a widely distributed African carnivoran, is a good model to compare with other African mammals. Here, we aimed to determine if its phylogeographical patterns depend on habitat preferences or other factors, such as dispersal capabilities. One nuclear and two mitochondrial markers were sequenced for marsh mongooses sampled throughout the species range, and sequences were also analysed for another widely distributed African mongoose, the whitetailed mongoose Ichneumia albicauda, previously studied, but more completely for this study. In the marsh mongoose we observed a deep divergence between West+Central Africa and East+South Africa, a pattern also observed in both forest and savanna mammals. With good dispersal capabilities and a preference for riparian habitats, the marsh mongoose may have been confined to forest refugia during Quaternary dry periods and may have used rivers as dispersal corridors. In contrast, in the white-tailed mongoose, the haplogroups were strongly divergent which may indicate more limited dispersal capabilities, but also reflect the preference of this species for more open habitats. These results suggest that life history traits, in addition to habitat preferences, had an impact on how these species were affected by past environmental changes, which is reflected in the geographical genetic structure today.
Antibacterial Activity of Metallic Nanoparticles against MultidrugResistant Pathogens Isolated from Environmental Samples: Nanoparticles/Antibiotic Combination Therapy and Cytotoxicity Study
(American Chemical Society, 2022-09-26) Adeniji, Oluwaseun Ola ; Ojemaye, Mike Onyewelehi ; Okoh, Anthony Ifeanyi
Multidrug-resistant organisms have increased the prevalence of infectious diseases and have become the leading source of death globally. The adverse effects associated with conventional antibiotics cannot be underestimated, and as a result, the quest for antibacterial agents has received great attention over the years. Therefore, the current research was designed to synthesize and examine the antibacterial properties of two metallic nanoparticles, silver nanoparticles (AgNPs) and zinc oxide nanoparticles (ZnONPs), as well as their antibiotic combination therapy against multidrug-resistant bacteria. AgNPs and ZnONPs were synthesized by the coprecipitation method and characterized. Thereafter, their antibacterial activity against multidrug-resistant bacteria was investigated using the microdilution technique. Subsequently, the interactions between the synthesized nanoparticles and antibiotics were evaluated by checkerboard assay. Time-kill assays were carried out to assess bacteriostatic or bactericidal effects, and the cytotoxicity study was carried out by MTT assay. The SEM analysis of AgNPs and ZnONPs were spherical with an average size of 21.03 and 43.37 nm, respectively. FTIR analysis showed the characteristics of the metal−oxygen vibrational band for both materials around 450 cm−1 , which indicated the successful synthesis of these antibacterial agents. The EDX characterization revealed Zn and O with 77.89% and 18.24% abundance in ZnONPs and Ag with 95.65% abundance in AgNPs. UV−vis absorption spectra of AgNPs was obtained around 400 nm. ZnONPs showed a moderate antibacterial effect against Enterococcus species with a MIC range of 2.5−5 mg/mL, while AgNPs demonstrated a strong antibacterial effect against the tested bacterial strains with a MIC range of 0.078−0.039 mg/mL. The ZnONPs were found to be cytotoxic against Vero cell lines at the tested concentrations, whereas AgNPs had no cytotoxic effect at lower concentrations. Their combination activities showed synergetic and additive effects. These findings revealed that these synthesized materials could serve as alternate antibacterial agents against multidrug-resistant Acinetobacter baumanni and Enterococcus species.
Assessing the Venturing of Rural and Peri-Urban Youth into Micro- and Small-Sized Agricultural Enterprises in the Eastern Cape Province, South Africa
(MDPI, 2023-10-31) Thibane, Zintle; Mdoda, Lelethu; Gidi, Lungile; Mayekiso, Anele
This study aimed to empirically assess the venturing by rural and peri-urban youth into micro- and small-sized agricultural enterprises in the Eastern Cape Province, South Africa. The aim of the study was achieved by focusing on the following specific objectives: analyzing youth involvement in agricultural enterprises; estimating the factors that influence youth participation in micro- and small-sized agricultural enterprises; and identifying constraints and opportunities for youth involvement in micro- and small-sized agricultural enterprises in the Eastern Cape Province. The study used multi-stage and snowballing sampling to select the respondents, and cross-sectional primary data were collected from 120 youths who ventured into micro- and small-sized agricultural enterprises. Only 70 youths from the sample participated in agricultural enterprises. The study was geared toward proposing a funding framework aligned with the characteristics of small- and micro-sized enterprises (SMEs) which can be used by both development finance institutions (DFIs) and commercial banks to assess applications for funding SMEs.
Assessment of socio-economic characteristics that determine farmers’ access to agricultural extension services in Eastern Cape, South Africa
(South African Journal of Agricultural Extension, 2021-04-26) Loki, O; Aliber, M ; Sikwela, M. M
The study reported on in this paper investigated smallholder farmers’ access to extension services. The study sought to distinguish the varying degrees of access to services of smallholder farmers engaged in different production systems, that is, home gardening, field cropping, and livestock production. The study was conducted in Raymond Mhlaba Local Municipalityin the Eastern Cape, specifically in two communities, namely Ngcabasa and Phathikhala villages. Research activities included a survey of 100 farmers as well asfocus group discussions. Employing logistic regression analysis, the study aimedto understand what influences whether or not a smallholder farmer accesses extension. The study also used various types of comparative statistics (T-test) to assess the implications of access to extension support, for instance for production and farm income. The main findings of the study were that 68% of the farming households interviewed in Ngcabasa and 71% of those in Phathikhala had access to extension services. Farmers who had access to extension had more farm income in both enterprises compared to those who had no access to extension services. From the regression analysis, farmers who were more likely to receive extension support appeared to be those who wereolder, those with less education, and those farming with livestock
Classification and Diagenetic Characteristics of the Cretaceous Sandstones in the Southern Bredasdorp Basin, Offshore South Africa
(Wiley, 2021-10-30) BAIYEGUNHI, Temitope Love ; LIU, Kuiwu ; GWAVAVA, Oswald ; BAIYEGUNHI, Christopher
A systematic petrographic and geochemical studies of 92 representative sandstone samples from exploration wells E-AH1, E-AJ1, E-BA1, E-BB1 and E-D3 in the southern part of the Bredasdorp Basin was undertaken to classify the sandstones as well as unravel the main diagenetic processes and their time relations. Petrographic study shows that the sandstones are largely subarkosic arenite and arkosic litharenite, which have underwent series of diagenetic processes as a result burial, rifting and subsequent uplift. The main diagenetic processes that have affected the reservoir properties of the sandstones are cementation by authigenic clay, carbonate and silica, growth of authigenic glauconite, dissolution of minerals and load compaction. The major diagenetic processes reducing the porosity are calcite cementation in the subarkosic arenite, and compaction and quartz cementation in arkosic litharenite. On the other hand, the formation of secondary porosity due to the partial to complete dissolution of early calcite cement, feldspars and minor grain fracturing has improved the reservoir property of the sandstone to some extent. The clay minerals in the sandstones commonly acts as pore choking cement, which reduces porosity. In general, there is no particular diagenetic process that exclusively controls the type or form of porosity evolution in the sandstones.
EFFECT OF PROCESSING METHODS ON CHEMICAL AND NUTRIENT COMPOSITION OF BAMBOO (Bambusae arundinacea) LEAVES
(Journal of Animal & Plant Sciences, 2021-08-13) Akinmoladun, O. F
Due to their abundant macro and micronutrients, some leaves hold a lot of promise as potential forage plants for livestock. However, a major limitation is the high content of anti-nutritional factors that combine with nutrients and reduce their bioavailability. This study, therefore, aimed to evaluate the effect of processing on the chemical and nutrient composition of bamboo leaves. The leaves were subjected to four different physical processing methods; T1 (control, air drying), T2 (fermenting in an airtight bag for five days), T3 (soaking in ordinary water for 24 h), and T4 (soaking in warmwater at 50 oC for 20 min). Fresh samples of the leaf were also analyzed on a wet basis (T5). Samples from respective treatment groups were analyzed for proximate composition, mineral constituents, anti-nutritional factors, vitamin C, flavonoids and antioxidant activities following standard procedures. The values obtained were subjected to a one-way analysis of variance using the generalized linear model of SAS. Although there was no significant effect of processing on ether extract and crude fiber, the crude protein content was significantly higher (P≤0.05) for T3 and T4. The ash content was lowest (P≤0.05) in T3 compared to other treatment groups. The fiber fractions (acid detergent lignin, neutral detergent fiber, hemicellulose and cellulose) were highest (P≤0.05) in T1 than other treatment groups. T1 had the lowest (P≤0.05) for phosphorous and potassium. However, T2, T3 and T4 had similar (P>0.05) phosphorous and sodiumcompositions. The processing effect was not significant (P>0.05) on vitamin C, alkaloids, saponins, and tannin. However, the phytate was highest (P≤0.05) in T1. The physical processing of bamboo leaves lowers the antinutrient appreciably without adversely affecting the proximate composition. Further, the high nutrient composition of bamboo leaves, irrespective of processing methods, attests to its potential as an important forage plant.
Effects of wood ash on physicochemical and morphological characteristics of sludge-derived hydrochar pellets relevant to soil and energy applications
(Elsevier, 2022-07-22) Mohammadi, Ali; Anukam, Anthony Ike; Granström, Karin; Eskandari, Samieh; Zywalewska, Martyna; Sandberg, Maria; Aladejana, Elizabeth Bosede
Hydrochar is produced through a process called hydrothermal carbonization (HTC) and constitutes a carbon-rich solid material with different remarkable applications. This study investigated the effects of wood ash on the physicochemical and morphological properties of biosludge-derived hydrochar in pelleted form relevant to the use of the pellets as a soil nutritional and liming agent and as a biofuel source. The hydrochar was mechanically compressed into uniformly-sized pellets under applied pressures of 4 and 8 kN after blending with varying percentages of wood ash in the order 0, 20 and 50%. The pure and blended pellets were characterized to determine the impact of wood ash on key properties, correlated to the two applications mentioned above. Results demonstrated a strong relationship between key features of the pellets and ash proportion. The wood ashblended hydrochar pellets showed good hydrophobicity as a consequence of increased contents of alkali and alkaline earth metals, but were low in aromatic functional groups compared to the pure hydrochar pellet. Furthermore, the heating value of the pure hydrochar pellet was about 4% higher than that of its parent material and indicates that this pellet has the capacity to serve as a source of energy. The study generally reveals that blending hydrochar produced from biosludge under HTC conditions with up to 20%–50% of wood ash and mechanically compressing into homogeneous pellets has promising potential for a nutrient-rich material that can enhance soil fertility.
Factors Influencing the Perceptions of Smallholder Farmers towards Adoption of Digital Technologies in Eastern Cape Province, South Africa
(MDPI, 2023-07-25) Bontsa, Nasiphi Vusokazi; Mushunje, Abbyssinia; Ngarava, Saul
The objective of the study was to determine the factors that influence the perceptions of smallholder farmers towards the adoption of digital technologies. A purposively selected sample of 250 smallholder farmers who were cross-sectionally surveyed from Port St Johns and Ingquza Hill Local Municipalities in South Africa was used in the study. The Technology Acceptance Model (TAM) and the Attention, Desire, and Action (AIDA) model were used to analyse the data. The results showed that digital technologies were perceived to be expensive, cause a digital divide, and discouraged the use of Indigenous Knowledge even though they increased production. Positive perception towards digital technologies was associated with cattle rearing, with extreme negative perception for sheep and goat rearing. Educational level, employment status, monthly income, household size, being part of a cooperative (1% level), age, and source of income (10% level) were significant factors affecting smallholder farmers’ perceptions of digital technologies. In conclusion, there are economic, social justice, and traditional perceptions towards digital technologies by smallholder farmers, with socio-economic factors affecting the perceptions. The study recommends providing low-cost digital technologies that promote Indigenous Knowledge, which should target the youth and young farmers with less education in small households who are full-time farmers with moderate-to-high incomes and are part of farmer groups/organisations.
Fatty acid profile, oxidative stability of lipids and sensory attributes of water restricted Xhosa goat meat supplemented with vitamin C
(CSIRO Publishing, 2021-09-21) Akinmoladun, O. F.; Fon, F. N.; Mpendulo, C. T. ; Hugo, A. ; Falowo, A. B.; Nantapo, C. T. W.
Context. Water scarcity often accompanied by limited water intake (WI) in livestock may result in pre-slaughter stress, thereby affecting meat quality parameters. Aims. This study was conducted to determine the effect of vitamin C (VC) supplementations on fatty acid (FA), lipids oxidation and sensory attributes of Longissimus lumborum muscles of Xhosa goats subjected to different watering regimen. Methods. In total, 42 goats were randomly assigned into seven treatments: without water restriction, WR (W0, control); WR of 70% of ad libitum WI (W70); WR of 50% ad libitum WI (W50); WR of 70% of ad libitum WI + 3 g VC daily (W70+); WR of 50% of ad libitum WI intake + 3 g VC daily (W50+); WR of 70% of ad libitum WI + 3 g VC and extra 5 g VC given every 8 days (W70++); WR of 50% of ad libitum WI + 3 g VC and extra 5 g VC given every 8 days (W50++). The goats were fed for 75 days and killed following standard procedures. Bodyweight changes, thaw loss, ultimate pH (pHu), thiobarbituric acid reactive substance (TBARS), moisture and fat content, sensory attributes and FA profile of the meat were evaluated. Key results. Results indicated that the decreased final weight in the untreated groups (W70 and W50) was reduced (P > 0.05) in the treated groups (W70+, W50+, W70++, W50++). The treatment effect was not significant (P > 0.05) on pHu, thaw loss and TBARS values. The moisture and fat content in the water-restricted groups were lower (P < 0.05) than in W0. The meat sensory appearance was affected (P < 0.05) by WR. Regardless of VC concentration, vaccenic and docosahexaenoic acid increased (P < 0.05), while linolenic acid decreased as the WR levels increased. Conclusions. WR of 70% and 50% of ad libitum WI, with or without VC, did not negatively affect the meat’s lipid oxidation and FA profile. Implications. Limited WI reduces body weight. However, a daily dose of VC could help reduce body weight loss during water scarcity.
Food habits and beliefs about Moringa oleifera among South African student mothers: a qualitative study
(EDP Sciences, 2022) Hedhili, Amel; Akinyemi, Babatope Ebenezer; Otunola, Gloria Aderonke ; Husson, Florence ; Valentin, Dominique
The problems of malnutrition constitute a major challenge in South Africa, particularly affecting the underprivileged populations ofthe EasternCape and Limpopo provinces. The present study aimedto gain an understanding of how to improve the nutritional intake of South African university student mothers and their children bytheintroduction ofMoringa oleifera intheir food. Focus Group Discussion wasimplemented attwo previously historically disadvantaged universities with predominantly black student populations, namely the University of Fort Hare and the University of Limpopo. Findings from the participants’ discussion about food habits and barriers to healthy eating show that there is a gap between healthy eating knowledge and eating habits. Despite the highlevel of awareness of the importance of nutritional intake, most of the study participants and their children consume less healthy foods. Due to the high cost of healthy food and their limited income, student mothers face substantial financial constraints when trying to make healthy changes in their food habits. Moreover, student mothers’ positive beliefs about the nutritional benefits of Moringa are insufficient to encourage its consumption. Finally, student mothers agree about using Moringa as a nutritional supplement. Maize porridge (pap) appears to be the preferred staple food for Moringa supplementation because of its palatability, satiating power, availability, affordability, and ease of preparation.
Geochemistry of the mudrocks and sandstones from the Bredasdorp Basin, offshore South Africa: Implications for tectonic provenance and paleoweathering
(De Gruyter, 2021-10-12) Baiyegunhi, Temitope Love ; Liu, Kuiwu ; Gwavava, Oswald ; Baiyegunhi, Christopher ; Rapholo, Maropene
An inorganic geochemical investigation of mudrocks and sandstone from the southern Bredasdorp Basin, off the south coast of South Africa was carried out to unravel the provenance, paleoweathering, and tectonic setting of the basin. Seventy-seven representative samples from exploration wells E-AH1, E-AJ1, E-BA1, E-BB1, and E-D3 underwent geochemical analysis involving major and trace elements. The major oxide compositions show that the sandstones could be classified as sub-arkose and sublithic arenite. The provenance discrimination diagrams based on major oxide geochemistry revealed that the sandstones are mainly of quartzose sedimentary provenance, while the mudrocks are of quartzose sedimentary and intermediate igneous provenances. The discrimination diagrams indicate that the Bredasdorp sediments were mostly derived from a cratonic interior or recycled orogen. The bivariate plots of TiO2 versus Ni, TiO2 against Zr, and La/Th versus Hf as well as the ternary diagrams of V–Ni–Th∗10 suggest that the mudrocks and sandstones were derived from felsic igneous rocks. The tectonic setting discrimination diagrams support passive-active continental margin setting of the provenance. Also, the closely similar compositions of the analysed samples and recent sedimentary rocks of the East African Rift System perhaps suggest a rifted basin tectonic setting for the Bredasdorp Basin. Chemical index of alteration (CIA) indices observed in the sandstones suggest that their source area underwent low to moderate degree of chemical weathering. However, the mudrocks have high CIA indices suggesting that the source area underwent more intense chemical weathering, possibly due to climatic and/or tectonic variations.
Middle-out ecology: small carnivores as sentinels of global change
(Wiley, 2022-04-28) Do Linh San.; Marneweck C.; Allen B.; Toowoomba Q.; Butler A.; Harris S.; Jensen A.; Saldo E.; Somers M.; Titus K.; Muthersbaugh M.; Ashoka A.; Jachowski D.
Species that respond to ecosystem change in a timely, measurable, and interpretable way can be used as sentinels of global change. Contrary to a pervasive view, we suggest that, among Carnivora, small carnivores are more appropriate sentinels than large carnivores. This reasoning is built around six key points: that, compared to large carnivores, small carnivores 1) are more species-rich and diverse, providing more potential sentinels in many systems; 2) occupy a wider range of ecological niches, exhibiting a greater variety of sensitivities to change; 3) hold an intermediate trophic position that is more directly affected by changes at the producer, primary consumer, and tertiary consumer levels; 4) have shorter life spans and higher reproductive rates, exhibiting more rapid responses to change; 5) have smaller home ranges and are more abundant, making it easier to investigate fine-scale management interventions; 6) are easier to monitor, manage, and manipulate. Therefore, we advocate for incorporatinga middle-out approach, in addition to the established top-down and bottom-up approaches, to assessing the responses of ecosystems to global change.
Nitrogen Use Efficiency of Quality Protein Maize (Zea mays L.) Genotypes
(MDPI, 2022-05-05) Adeoluwa, Olusola Oluyinka ; Mutengwa, Charles Shelton ; Chiduza, Cornelius ; Tandzi, Ngoune Liliane
Use of more nutrient-use efficient Quality Protein Maize (QPM) varieties will likely playa pivotal role in maintaining or increasing crop yields and nutritional values in fields where soils are degraded. This study aimed to: (i) assess the nitrogen use efficiency (NUE) of different QPM inbred lines at various levels of nitrogen (N) fertilizer application; (ii) determine the relationships among NUE indices and yield; and (iii) determine the appropriate rate of fertilizer application for QPM genotypes under conditions of this study. Thirty-two QPM inbred lines were evaluated at 0, 30, 60, 90 and 120 kg N ha−1 N fertilizer application in a split-plot randomized complete block design with two replicates at the University of Fort Hare Crop Research farm, South Africa. Results revealed highly significant differences (p ≤ 0.001) for total nitrogen in biomass (Bio Total N), total nitrogen in grain (G Total N), grain yield, NUE and almost all the indices estimated across N levels. The top three genotypes which showed high-yielding potential at 30 kg N ha−1 include L2 (6.24 t/ha), L3 (6.47 t/ha) and L4 (6.34 t/ha), and were considered the most N-efficient genotypes under low N soils. The highest grain yields (6.74 t/ha) and highest NUtE (Nitrogen Utilization Efficiency) (1.93 kg grain/total N) were obtained at 90 kg N ha−1 . Highly significant and positive correlation coefficients were found between NUE and yield (+0.9), NUE and NUtE (+0.9), NUE and HI (Harvest Index) (+0.5), NUtE and yield (+0.99), HI and yield (+0.5) and NUtE and HI (+0.5). Highest nitrogen uptake efficiency (NUpE) was obtained from the lowest fertilizer rate, which was 30 kg N ha−1
Prevalence of classes 1 and 2 integrons in multidrug‑resistant Acinetobacter baumanni isolates recovered from some aquatic environment in South Africa
(Nature Research, 2022-11-24) Adeniji, Oluwaseun Ola ; Elsheikh, Elsiddig A. E.; Okoh, Anthony Ifeanyin
Proximate, Vitamins, Minerals and Anti-Nutritive Constituents of the Leaf and Stem of Helichrysum odoratissimum (L.) Sweet: A Folk Medicinal Plant in South Africa
(MDPI, 2022-10-20) Afuape, Abolaji Olajumoke ; Afolayan, Anthony Jide; Buwa-Komoreng, Lisa Valencia
Helichrysum odoratissimum (L.) Sweet (Asteraceae) is a perennial shrub used in South African folk medicine to combat human diseases such as diabetes, coughs, asthma, and diarrhoea, and for wound treatment. This study evaluated the leaf and stem of H. odoratissimum for their nutritive and anti-nutritive qualities using the standard methods of the Association of Official Analytical Chemists (AOAC), atomic absorption spectrometry (AAS) and colorimetry. Crude fat and protein were high in the leaf (7.61% and 7.82% DW), but low in the stem (2.25% and 3.4%), respectively. The neutral detergent fibre (NDF) content was significantly higher in the stem (68.5%) compared to the leaf (43.6%), while non-fibre carbohydrate (NFC) in the leaf (24.93%) was higher than in the stem (15.67%). Mineral analysis showed that both the leaf and stem of H. odoratissimum are good sources of potassium, calcium, sodium, magnesium, phosphorus and iron. Appreciable amounts of vitamins B2, C and E in the leaf and stem supports the folkloric utility of the plant in the traditional treatment of wounds, coughs and colds. A tolerable amount of phytate in both leaf (0.36%) and stem (1.06%) might be a factor for safer consumption of the plant as food and medicine. These findings suggest the use of the plant as a source for dietary supplementation and ethnomedicinal applications.
Soil C sequestration and CO2 fluxes under maize-based Conservation Agriculture systems in the Eastern Cape, South Africa
(Taylor and Francis, 2021-05-15) Muzangwa, Lindah ; Mnkeni, Pearson Nyari Stephano ; Chiduza, Cornelius
Traditional farming methods deplete soil carbon and contribute to carbon dioxide (CO2) emissions. We investigated the effects of Conservation Agriculture principles on C sequestration and CO2 flux from two agroecological regions in the Eastern Cape province, South Africa, over five cropping seasons in the period 2012–2015. The field trials were laid in a split–split plot design. The main treatments were the tillage system, as conventional tillage or no-till. The sub-treatments were the crop rotation pattern: maize–fallow–maize (MFM); maize–fallow–soybean (MFS); maize– wheat–maize (MWM); or maize–wheat–soybean (MWS). Residue management after each crop in rotation was residue removal (R–) or residue retention (R+). The biomass and C-inputs by the crop rotations were both in the order: MWM > MWS > MFM > MFS. R+ resulted in greater levels of particulate organic matter (POM) than R–. The former was the only factor to significantly (p < 0.05) increase soil organic carbon (SOC) in the 0–5 cm depth layer at both sites after two years. CO2 flux under conventional tillage was 20% higher than with no-till. The CO2 fluxes were significantly influenced by air temperature (p < 0.001, r2 = 0.41) and soil bulk density (p < 0.001, r2 = 0.16). The results suggest that MWM or MWS crop rotation in conjunction with R+ under no-till offer the greatest potential for biomass and C-inputs, and consequently C sequestration, in sub-humid and semi-arid agroecological regions of South Africa.
Solar Photovoltaic Modules’ Performance Reliability and Degradation Analysis—A Review
(MDPI, 2022-08-17) Alimi, OA; Meyer, EL ; Olayiwola, O
The current geometric increase in the global deployment of solar photovoltaic (PV) modules, both at utility-scale and residential roof-top systems, is majorly attributed to its affordability, scalability, long-term warranty and, most importantly, the continuous reduction in the levelized cost of electricity (LCOE) of solar PV in numerous countries. In addition, PV deployment is expected to continue this growth trend as energy portfolio globally shifts towards cleaner energy technologies. However, irrespective of the PV module type/material and component technology, the modules are exposed to a wide range of environmental conditions during outdoor deployment. Oftentimes, these environmental conditions are extreme for the modules and subject them to harsh chemical, photo-chemical and thermo-mechanical stress. Asides from manufacturing defects, these conditions contribute immensely to PV module’s aging rate, defects and degradation. Therefore, in recent times, there has been various investigations into PV reliability and degradation mechanisms. These studies do not only provide insight on how PV module’s performance degrades over time, but more importantly, they serve as meaningful input information for future developments in PV technologies, as well as performance prediction for better financial modelling. In view of this, prompt and efficient detection and classification of degradation modes and mechanisms due to manufacturing imperfections and field conditions are of great importance towards minimizing potential failure and associated risks. In the literature, several methods, ranging from visual inspection, electrical parameter measurements (EPM), imaging methods, and most recently data-driven techniques have been proposed and utilized to measure or characterize PV module degradation signatures and mechanisms/pathways. In thispaper, we present a critical review of recent studies whereby solar PV systems performance reliability and degradation were analyzed. The aim is to make cogent contributions to the state-of-the-art, identify various critical issues and propose thoughtful ideas for future studies particularly in the area of data-driven analytics. In contrast with statistical and visual inspection approaches that tend to be time consuming and require huge human expertise, data-driven analytic methods including machine learning (ML) and deep learning (DL) models have impressive computational capacities to process voluminous data, with vast features, with reduced computation time. Thus, they can be deployed for assessing module performance in laboratories, manufacturing, and field deployments. With the huge size of PV modules’ installations especially in utility scale systems, coupled with the voluminous datasets generated in terms of EPM and imaging data features, ML and DL can learn irregular patterns and make conclusions in the prediction, diagnosis and classification of PV degradation signatures, with reduced computation time. Analysis and comparison of different models proposed for solar PV degradation are critically reviewed, in terms of the methodologies, characterization techniques, datasets, feature extraction mechanisms, accelerated testing procedures and classification procedures. Finally, we briefly highlight research gaps and summarize some recommendations for the future studies.
Stress amelioration potential of vitamin C in ruminants: a review
(Springer, 2021-12-27) Akinmoladun, Oluwakamisi Festus
Ruminants, as well as other livestock, can synthesize vitamin C (VC) in their liver, and therefore, dietary requirements from exogenous supplementation are often ignored. However, metabolic demand may be exceeded, leading to a decreased endogenous synthetic capacity of VC following exposure to stressful conditions. Such conditions include high thermal load, limited water intake (induced by water scarcity), physiological status and infectious diseases. The obvious consequences are decreased performance, susceptibility to infections and increased mortality. This review discusses the potential role of vitamin C in ruminants’ stress management and summarizes the in vitro and in vivo research to date. The different administration routes, comparative advantages and supplementation outcomes on growth, production parameters and physiological status were also identified. Also, areas where there was a lack of evidence or controversy, including critical literature research gaps, were identified, while the mechanism of VC’s actions on significant outcomes was explained.

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