Ergonomic evaluation of manually-operated peanut butter mills

No Abstract Available JASSA: Journal of Applied Science in Southern Africa Vol.8(2) 2002: 76-8

Removal of nutrient and heavy metal loads from sewage effluent using vetiver grass, Chrysopogon zizanioides (L.) Roberty

Urban cities in many developing nations face the challenge of relieving the pressure exerted on overloaded sewage treatment works. Apart from limited financial capacity, complementary treatment methods like phyto-extraction of pollutants from the effluent have not been fully exploited, particularly in southern Africa. A study was conducted in Harare, Zimbabwe, to assess the potential of vetiver grass, Chrysopogon zizanioides, in removing N, P, Zn, Mn and Ni loads in sewage effluent from primary clarification, under hydroponic conditions. Vetiver grass was grown from tillers on floating trays suspended in effluent, and the total concentrations of selected parameters were monitored in both effluent and vetiver grass at 0, 7, 14 and 21 days of retention in effluent. Higher pollutant reduction (62–100%) in effluent, with respect to all parameters, under vetiver grass compared to no vetiver treatment (9–27%), was recorded by Day 21. Effluent pH remained stable at 7.44–7.64. Smaller changes were found for N (9.8 from 27.5 mg∙ℓ–1) and P (2.0 from 5.3 mg∙ℓ–1) than for the heavy metals. Vetiver grass dry biomass accumulated at 3.8–4.7 g∙tiller–1∙week–1, while heavy metal extraction (up to 6.2 mg Zn, 3.3 mg Mn and 0.06 mg Ni tiller–1) by root uptake increased with time at an exponential rate (R2, 0.73–0.83). The study established that, while root uptake was a significant feature of the clean-up process, the corresponding high reduction of heavy metals in effluent suggests multiple removal mechanisms, including bio-sorption by microorganisms producing an immobilised microbial biomass on the container wall. A deliberate lowering of effluent pH may increase root uptake thereby possibly reducing the clean-up time and improving effluent quality. There is potential for application of this technology in cities struggling with the cost of conventional sewage treatment

Farmer perceptions on climate change and variability in semi-arid Zimbabwe in relation to climatology evidence

Farmers in semi-arid Zimbabwe prioritise climate variability as their major agricultural productivity-reducing problem. This paper raises the importance of considering local farmers perceptions on climate risk, as this greatly influences on-farm investments and decision-making in agricultural management and production in semiarid Zimbabwe. A study was conducted in two districts of semi-arid Zimbabwe using participatory research techniques, to investigate farmers perceptions of climate variability and whether these perceptions correspond with historical climatic data. The study showed that farmers perceived climatic and weather patterns to have changed over the past decade or two, as indicated by erratic rainfall patterns, decreased rainfall and temperature increases, leading to crop productivity decline and increased livestock morbidity and mortality. Majority of respondents (75%; n=81) were highly risk-averse, perceiving that most of the seasons in any ten given years could be poor. The climatic data show no evidence that corroborates the farmers perceptions, with only temperature showing a clear signal, indicating the influence of other non-climatic factors. The climate data show rainfall variability to be a normal characteristic of the study sites, with deviations from the climatic rainfall means (or the poor seasons) being cyclical and occurring once in every three seasons over the past 40 years. The study highlights strategies that farmers could implement to enhance agricultural productivity in the semi-arid areas to adapt to climate change and variability

Postharvest agriculture in changing climates: Its importance to African smallholder farmers

Climate change and variability affect not only the field stages and yields of crops, but also what happens to them after harvest. There has been little discussion of the impacts of climate change on postharvest agriculture, and still less on these impacts in developing countries. Many studies have focused on potential crop yield and pre-harvest implications of different climatic projections, but have omitted an analysis of the need and ability to then protect this increasingly valuable harvest as a vital aspect of food security. Postharvest systems will be affected by changes in temperature, rainfall, humidity, extreme events and the natural and human responses to climate change and variability. This study describes typical grain postharvest systems in east and southern Africa and discusses the likely impacts of different climate change trends on postharvest activities, assets and human well-being outcomes. Adaptation opportunities for creating more climate resilient postharvest agricultural systems and associated livelihoods are identified. Many of these adaptation opportunities are already known and understood by postharvest service providers, highlighting the significant challenge of getting postharvest knowledge into use at a larger scale. A discussion is presented on the factors influencing attempts to strengthen the adaptive capacity of postharvest systems, such as its invisibility, its omission from training curricula, innovation system challenges, the policy bias towards pre-harvest agricultural spending, limited understanding of gender and diversity aspects of postharvest roles, and the dominance of maize in the food system. The study recognises the crucial role of postharvest agriculture in helping communities adapt and cope with change