Department of Agricultural and Rural Engineering

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    ItemOpen Access
    Electrical properties of maize kernels contaminated with aflatoxin
    (2018-09) Muga, Francis Collins; Workneh, Tilahun Seyoun; Marenya, Moses Okoth
    The purpose of this study was to investigate the effect of aflatoxin contamination on the dielectric constant of maize kernels. A factorial experiment comprising of three levels of moisture content (13.3%, 15.3%, and 16.4%), three frequencies (25, 50, and 100 kHz), and nine levels of aflatoxin contamination (0, 1.5, 2.6, 10, 50, 100, 150, 172, and 230 μg kg-1) was used. The maize kernels were poured into a custom-built sample holder comprising a shielded parallel plate capacitor. An ISO-TECH LCR-821 meter was used to measure the capacitance, from which the dielectric constant was computed. The results indicated that moisture content and frequency significantly (p≤0.05) affected the dielectric constant. The dielectric constant increased with increase in moisture content and decreased with increasing frequency. However, aflatoxin contamination level had no significant (p>0.05) effect on the dielectric constant of maize kernels. The coefficient of determination (R2) of dielectric constant and aflatoxin contamination levels was low (R2 = 0.2687), indicating a poor correlation between the aflatoxin levels and the dielectric constant of maize kernels. Based on the findings, the dielectric constant is unsuitable for predicting the level of aflatoxin contamination in maize kernels within the 20-200 kHz frequency range.
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    ItemOpen Access
    Evaluation of solid food waste for biogas and manure production: a case study of the University of Venda Canteen Solid Food Waste
    (2023-05-29) Mhlanga, Prosper; Marenya, M. O.; Tinarwo, D.; Tavengwa, N. T.
    The ever-increasing food waste generated globally attracts grave concerns due to associated environmental and socio-economic implications. One way to mitigate these adverse consequences is to use the food waste as feedstock for valuable energy and fertilizer generating anaerobic digestion (AD) process. While AD is a widely accepted method for managing and valorising food waste (FW), in South Africa, its use is in the infancy stage. Lack of awareness and adequate knowledge of the potential of FW for biogas and manure production could be the reason for the observed slow uptake of AD in South Africa. This study evaluated the energy and manure production potential of solid FW generated by a typical South African university (the University of Venda) canteen using the AD co-digestion of solid FW and cow dung (CD). In the first part of the study, a 2 x 5 factorial experimental design was used to assess the effect of substrate mixing ratios and temperature on biogas yield, methane content, and biochemical methane potential (BMP) of pure FW and CD and co-digestion of FW and CD for predetermined mixing ratios. FW and CD mixed on a wet mass basis at ratios 0:100, 25:75, 50:50, 75:25, and 100:0 (w/w) were batch incubated at 35±1℃ and 55±1℃. Experimental results were subjected to analysis of variance (ANOVA) at a 5% level of significance. Where a significant ANOVA result was obtained, the mean separation was done using Fisher’s least significant difference (LSD) test at a 5% level of significance. The obtained results showed that the temperature and substrate mixing ratios significantly (p < 0.05) affected biogas yield, biogas methane content, and BMP. The highest biogas yield and BMP were 4903.33 ± 38.84 mL and 301.879 ± 2.07 mLCH4/g VS at 35 °C, and 7151.67 ± 11.55 mL and 401.88 ± 1.98 mLCH4/g VS at 55 °C. The lowest biogas and BMP yields were 5301.67 ± 62.51 and 328.278 ± 4.265 mLCH4/g VS at 55 °C, and 3291.67 ± 81.45 mL and 328.28 ± 4.26 mLCH4/g VS, respectively, for mono-digestion of FW at 55 ° and 35 °C. Overall, co-digestion of FW and CD produced higher biogas yield and BMP than mono-digestion of the substrates at both test temperatures. These findings can be used to size heated and unheated biogas plants using co-digested FW and CD substrates. In the last part of the study, a 2 x 2 factorial experimental design was used to assess the effect of substrate type and temperature on the quality of bio-slurry. The bio-slurry samples were collected from mono-digestion of FW and CD which were incubated at 35±1℃ and 55±1℃. The obtained results indicated that bio-slurry quality was significantly affected (p < 0.05) by substrate type, temperature, and the interaction between substrate type and temperature. Bio-slurries had lower total solids (TS %) and (volatile iii solids/total solids) VS/TS% compared to undigested FW and CD. Bio-slurry from the AD of FW and CD at 55 ℃ had significantly higher (p < 0.05) NPK concentrations than bio-slurry obtained from AD at 35 ℃. The highest nitrogen (0.25%), phosphorous (1.61%) and potassium (1.25%) concentrations were obtained from bio-slurry obtained the AD of CD at 55 ℃. Characterization data for bio-slurry from mono-digested FW and CD can be used to advise biogas plant owners, agricultural extension officers and the public on the application rates of co-digested FW and CD slurry as manure depending on crop nutrient requirements.
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    Investigation of Coping Mechanisms on Food Systems Synergy Discrepancies Caused by Climate Change Among Young Agripreneurs in Musina Municipality of the Vhembe District
    (2026-05-19) Phaswana, Dakalo; Tshikororo, M.
    Climate change continuously disrupts agricultural stability by affecting all segments of the food system. Climate change determinants, such as rising temperatures, and extreme weather events, disrupt the food system, leading to discrepancies within the food system, including market volatility. The study aimed to investigate the coping mechanisms used by young agripreneurs in Musina municipality to address discrepancies in food systems synergy caused by climate change. The study sample consisted of 94 participants, and simple random sampling was used to select the sample. A structured questionnaire was used as a data collection tool. Descriptive statistics were employed to analyse the socio-economic characteristics of youth agripreneurs and determine the food system discrepancies that youth agripreneurs are facing. Multinomial logistic regression was employed to assess the impact of food system synergy discrepancies on the sustainability of youth agripreneurs. The study uncovered that the majority of youth agripreneurs were females and aged between 30 and 35; Furthermore, a significant number of youth agripreneurs possessed secondary education, followed by tertiary education. The study also revealed that major disruptions within the industry segment included an increase in maintenance costs, fluctuations in input prices, delayed supply, irregular input supply, and production inconsistency. Within the commerce segment, the major disruptions that youth agripreneurs highlighted were reduced supply quality, a lack of storage facilities, and a high perishability rate. In the trade segment, major disruptions included market price fluctuations, changes in consumer demand, and supply competition. The study also revealed that most discrepancies faced by youth agripreneurs severely affect their short-term sustainability, more so than their medium-term and long-term sustainability. The study also uncovered that most youth agripreneurs diversify their input suppliers, markets, and distribution channels as their coping mechanism. The study conclude that while most youth agripreneurs are predominantly females with moderate education, they employ more reactive than proactive coping mechanisms to mitigate climate induced impacts. The study recommends prioritising investments in input manufacturing facilities to stabilise the input prices.
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    Investigation of Technical and Operational Determinants of Sustainability of Agricultural Cooperatives in the Vhembe District, South Africa
    (2026-05-19) Mushukwa, Thanyani Cynthia; Tshikororo, M.; Nefale, T. A.
    Many residents of the Vhembe District Municipality are primarily affected by food insecurity, unemployment, and poverty. As a result of these primary issues, most people turn to farming to ensure food security, alleviate poverty, and generate jobs in their rural communities. Farmers often join forces by forming cooperatives, which allow them to share resources, support one another, and strengthen their business under improved conditions. These cooperatives not only enhance agricultural productivity but also foster resilience and solidarity within rural communities. The study investigated the technical and operational determinants of the sustainability of agricultural cooperatives. The research used a quantitative method. The study was conducted in Vhembe District Municipality. A purposive sampling method was used to sample the four local municipalities within the Vhembe District Municipality. A sample size of 123 agricultural cooperatives was used for analysis. Data were collected using a questionnaire administered during face-to-face interviews. Three methods of data analysis were used in the study: descriptive statistics, discriminant analysis, and a binary logistic regression model. The study revealed the socio-economic characteristics of respondents, with most respondents being between 45 and 59 years old and having more than 10 years of farming experience. The study also found that most agricultural cooperatives were not sustainable (56.9%), while those that were sustainable accounted for 43.1%. The results indicated that agricultural cooperative members could not operate their cooperatives continuously for an extended period of time. The study found that governance largely differed based on decision-making processes, stakeholder involvement, and leadership composition within the agricultural cooperatives. The study concluded that some technical and operational factors contribute to the sustainability of agricultural cooperatives, but most were found to be unsustainable. These are some of the challenges that agricultural cooperatives face: monitoring and evaluation, leadership issues, conflicts among members, member dishonesty, and member attrition. The study concludes by recommending regular monitoring and evaluation of operational and technical aspects to enhance the sustainability of agricultural cooperatives.