Mineralogy and Geochemistry of Soils of Ultramafic Origin from the Great Dyke, Zimbabwe and Gillespie County, Texas

Although soils developed from ultramafic parent materials have significance to agriculture, ecology and health, their bio-geochemistry is poorly understood. The mineralogical and bio-geochemistry of soils formed from the ultramafic parent materials of the Great Dyke, Zimbabwe and Gillespie County, Texas was investigated. The objectives were to determine the mineralogical and bio-geochemical properties of the soils in order to assess the potential impact and challenges to agriculture, and environmental quality. Soil samples were taken from the crest, shoulder, footslope and the toeslope. Chemical analyses were performed by nuclear and spectroscopic techniques. Mineral characterization was conducted by x-ray diffraction (XRD) and spectroscopic techniques. Microbial whole-community structure was determined by the fatty acid methyl esters (FAME) technique. The results indicate wide chemical and mineralogical compositions among the studied sites. The soils contain relatively high concentrations of heavy metals (some sites contain Cr(VI)), but low levels of K and Ca. The highest concentrations of trace metal were associated with chromite, Fe oxides and serpentinite. The concentrations of Mg were higher than those of Ca and varied between Zimbabwe and Texas soils largely due to the parent materials. Unique to these soils is the occurrence of talc, serpentine, chlorite, Fe-rich smectite, amphiboles, pyroxenes, Fe and Cr oxides in relatively large amounts. These soils also lack micas and have neglible amounts of kaolinite and feldspars. Palygorskite and serpentine occurred in specific soil horizons and at specific landscape positions. FAME profiles indicate that the soil microbial community structure is predominantly bacteria and fungi (including arbuscular mycorrhiza fungi) at each landscape position across the transect. Biomarkers for actinomycetes were undetectable. The proportions of Gram-positive bacteria were higher than those of the Gram-negative bacteria. Very low levels of nutrients (Ca and K), higher Mg/Ca molar ratios, and the relatively high concentrations of heavy metals in these soils impact agricultural productivity. High concentrations of heavy metals, the presence of the Cr(VI) as well as its great potential to form in these soils might impact microbial activity and environmental quality. The occurrence of fibrous minerals (e.g serpentine and amphiboles) in these soils will likely impact human health

Intake and growth performance of Brahman and Boran crossbred heifers fed on optimized ash-based vitamin-mineral winter block with bentonitic clay binders

Though use of cement as a binder has produced acceptable results in the manufacture of feed block, there are questions on the possible negative health effects and high cost associated with the use of building cement in the production of feed blocks. The objective of the study was to compare supplementation effect of cement and bentonite + cement as binders in optimised ash-based winter blocks on feed intake, weekly weight gain and hair characteristics of beef cattle. Sixteen Brahman x Boran crossbred heifers with initial body weight of 250 ± 5kg were allocated to four treatments in a completely randomized design. Treatments based on the binder used in fabricating the optimized ash-based vitamin-mineral winter block were: cement agglutinated block, bentonite + cement agglutinated block, negative control (no supplement), and positive control (commercially available winter block). Animals were penned and fed on Rhodes grass (Chloris gayana) hay constituting 11% crude protein (CP); 8 MJ/kg DM for seventy days (dry season). Feed and supplement blocks were weighed daily animal weights were collected on weekly basis. Hair samples were measured at the beginning and end of the experiment. There was no significant difference in voluntary feed intake between bentonite + cement block and the positive control (P0.05). Block intake was significantly higher (P0.05) for the commercially available block (0.70±0.05kg/head/day) than in the cement agglutinated block (0.44±0.04 kg/head/day) and the bentonite + cement agglutinated block (0.49±0.04 kg/head/day). All animals that received supplement block had significantly higher weight gains than those that did not receive supplement (P0.05). There was no significant difference in hair length across all treatments (P0.05). Ash-based winter block agglutinated by a combination of cement and bentonite clay is a viable supplement which helps trim down amount of cement in feed blocks and improve animal performance. Use of the locally produced optimised ash-based vitamin-mineral block for nourishing ruminant animals is highly recommended

A spatial assessment of stream-flow characteristics and hydrologic alterations, post dam construction in the Manyame catchment, Zimbabwe

The global hydrologic regime has been intensively altered through activities such as dam construction, water abstraction, and inter-basin transfers. This paper uses the Range of Variability Approach (RVA)  and daily stream flow records from nine gauging stations to characterize stream-flow post dam construction in the Manyame catchment, Zimbabwe. We identify which variables continue to be altered, upstream and at different distances downstream, to distinguish sections with the highest  potential for ecological disruption and to understand how hydrological alterations dissipate downstream of dams. Our results indicate that different sections of the same river have different stream-flow  characteristics post dam construction. The most adverse effects of dams were on downstream stretches of the river which were characterized by low flows, extreme low flows and an increased number of zero-flow days. These differences reflect the  operation rules of the Manyame catchment dams. While the change in stream-flow characteristics is  apparent in the 0–10 km range, it is slightly felt in the 11–20 km range and totally disappears at distances >20 km downstream of dams. These changes in stream characteristics, and that damming is only restricted to the upper third of the catchment, make the hydrologic fragmentations in the catchment minor. However, the continued hydrologic alterations post dam construction raise important concerns about the interactions of hydrology with other factors like sediment deposition upstream of dams and climate change. We  recommend that catchment managers target enhancing the natural flow variability of the river instead of meeting target flows.Keywords: damming, range of variability approach, stream-flow characteristic

Agro-Ecological Distribution and Consumption of Wild Harvested Edible Insects, Fruits, and Vegetables in Rural Zimbabwe

Natural resources are a valuable component of traditional food systems that contributes to food and nutrition. The distribution and consumption patterns of these natural resources still needs exploration for follow-up research and optimum utilisation. The aim of this study was to investigate the agro-ecological distribution and the consumption of wild harvested edible insects, indigenous fruits and vegetables in rural Zimbabwe. Secondary data generated from a cross-sectional survey targeting 11,973 randomly selected households rural districts was used. The results revealed that at least 14 wild harvested edible insect species, 26 indigenous fruits and 10 indigenous vegetables are commonly consumed. The results showed that the highly consumed indigenous fruits, vegetables and insects were widely distributed in all provinces irrespective of the agro-ecological region and varied due to rainfall pattern and also due to soil type. However, their distribution was in some cases restricted to specific administrative boundaries or provinces. Consumption pattern and preference for some insects, fruits and vegetables varied with province. The distribution and consumption data presented in this study offers an opportunity to advocate for the conservation, production, processing and promotion of specific species in districts by relevant stakeholders and can be used as an advocacy tool for policymakers

Independent and combined effects of improved water, sanitation, and hygiene, and improved complementary feeding, on child stunting and anaemia in rural Zimbabwe: a cluster-randomised trial.

BACKGROUND: Child stunting reduces survival and impairs neurodevelopment. We tested the independent and combined effects of improved water, sanitation, and hygiene (WASH), and improved infant and young child feeding (IYCF) on stunting and anaemia in in Zimbabwe. METHODS: We did a cluster-randomised, community-based, 2 × 2 factorial trial in two rural districts in Zimbabwe. Clusters were defined as the catchment area of between one and four village health workers employed by the Zimbabwe Ministry of Health and Child Care. Women were eligible for inclusion if they permanently lived in clusters and were confirmed pregnant. Clusters were randomly assigned (1:1:1:1) to standard of care (52 clusters), IYCF (20 g of a small-quantity lipid-based nutrient supplement per day from age 6 to 18 months plus complementary feeding counselling; 53 clusters), WASH (construction of a ventilated improved pit latrine, provision of two handwashing stations, liquid soap, chlorine, and play space plus hygiene counselling; 53 clusters), or IYCF plus WASH (53 clusters). A constrained randomisation technique was used to achieve balance across the groups for 14 variables related to geography, demography, water access, and community-level sanitation coverage. Masking of participants and fieldworkers was not possible. The primary outcomes were infant length-for-age Z score and haemoglobin concentrations at 18 months of age among children born to mothers who were HIV negative during pregnancy. These outcomes were analysed in the intention-to-treat population. We estimated the effects of the interventions by comparing the two IYCF groups with the two non-IYCF groups and the two WASH groups with the two non-WASH groups, except for outcomes that had an important statistical interaction between the interventions. This trial is registered with ClinicalTrials.gov, number NCT01824940. FINDINGS: Between Nov 22, 2012, and March 27, 2015, 5280 pregnant women were enrolled from 211 clusters. 3686 children born to HIV-negative mothers were assessed at age 18 months (884 in the standard of care group from 52 clusters, 893 in the IYCF group from 53 clusters, 918 in the WASH group from 53 clusters, and 991 in the IYCF plus WASH group from 51 clusters). In the IYCF intervention groups, the mean length-for-age Z score was 0·16 (95% CI 0·08-0·23) higher and the mean haemoglobin concentration was 2·03 g/L (1·28-2·79) higher than those in the non-IYCF intervention groups. The IYCF intervention reduced the number of stunted children from 620 (35%) of 1792 to 514 (27%) of 1879, and the number of children with anaemia from 245 (13·9%) of 1759 to 193 (10·5%) of 1845. The WASH intervention had no effect on either primary outcome. Neither intervention reduced the prevalence of diarrhoea at 12 or 18 months. No trial-related serious adverse events, and only three trial-related adverse events, were reported. INTERPRETATION: Household-level elementary WASH interventions implemented in rural areas in low-income countries are unlikely to reduce stunting or anaemia and might not reduce diarrhoea. Implementation of these WASH interventions in combination with IYCF interventions is unlikely to reduce stunting or anaemia more than implementation of IYCF alone. FUNDING: Bill & Melinda Gates Foundation, UK Department for International Development, Wellcome Trust, Swiss Development Cooperation, UNICEF, and US National Institutes of Health.The SHINE trial is funded by the Bill & Melinda Gates Foundation (OPP1021542 and OPP113707); UK Department for International Development; Wellcome Trust, UK (093768/Z/10/Z, 108065/Z/15/Z and 203905/Z/16/Z); Swiss Agency for Development and Cooperation; US National Institutes of Health (2R01HD060338-06); and UNICEF (PCA-2017-0002)