Zinc uptake by vegetables: Effects of soil type and sewage sludge

Studies were carried out to investigate how sludge applied to 3 soil types to improve the yield of carrots (Daucus carota) and spinach (Spinacea oleracea) would affect the amount of Zn taken up by thesevegetables. A 3 year old (type 1 sludge) and a 3 month old (type 2 sludge) sludge were applied to a vertisol, an arenosol, a chromic/calcic luvisol and a ferric luvisol at (v/v, %) ratios of 0:100, 5:95, 10:90,20:80, and 40:60 sludge : soil. Spinach and carrots were grown on these soil-sludge mixtures for 9 and 13 weeks, respectively, after which the concentration of Zn in both was determined. Sludge applicationresulted in an increase in total Kjeldahl nitrogen (TKN), available phosphorus, organic matter content, (OM) and cation exchange capacity (CEC) of soils. Percentage increase varied with soil type but rangedfrom 900 - 3600%, 700 - 3000%, 60 - 300% and 9 - 600% for TKN, available phosphorus, OM, and CEC, respectively. Sludge application also increased the fresh weight of spinach by up to 31% and carrots byup to 10%, these increases also varied with type of soil on which vegetable was grown. Spinach accumulated more Zn than carrots. Carrots and spinach grown on the arenosol had the highest mean concentration of Zn with values of 131.58 mg/kg and 86.33 mg/kg, respectively. Soil type, sludge age and sludge application rate may not individually affect the amount of Zn accumulated by these vegetables, but they could interact to increase the uptake

Microbiological and health related perspectives of geophagia: An overview

Geophagia, which refers to the deliberate eating of soil, is considered to be a deviant eating disorder, a sequel to poverty and famine but could also be observed in the absence of hunger and in both scenarios may be associated with high degree of mortality and morbidity. The phenomenon has been reported to be common among pregnant women, lactating women, school children and people with psychiatric disorders. The microbiology of soil shows a broad diversity and functionality of soil microflora which impact variously on soil and its consumption. Soil microbes contribute immensely to the quality of soil and even determine soil types. Geophagia may be beneficial or harmful. Beneficial aspects include the use of kaolin to treat diarrhea, gastritis, colitis, enhancement of bioactivities and maintenance of normal intestinal flora by commensal flora found in soil. Clay or soil containing special constituents are valuable oral and topical antimicrobials as well as adsorbents of toxins. Microbiological underpinnings of geophagia include the ingestion of eggs of parasitic worms such as Ascaris lumbricoides, Trichuris trichiura with the health consequences. Highly toxigenic bacteria such as Clostridium perfringens, Clostridium tetani, Clostridium botulinum, the causative agents of gas gangrene, tetanus and botulism and other human pathogens may be ingested. It has also been postulated that indirect consumption of soil may pose serious health problems. For example, nitrate run-off and leaching from soil into water bodies may lead to eutrophication and colonization by toxic cyanobacteria with ripple medical effects such as gastroenteritis. Some general health implications of geophagia include association with iron deficiency and anemia, intestinal obstruction, constipation, peritonitis, dental damage, eclampsia, iron deficiency and even mortality. The interplay of factors involved in geophagia, though varied, intricate and researched may not have been fully elucidated. Further concerted efforts aimed at multidisciplinary research are warranted so as to address gaps in the corpus of knowledge on the important subject.Keywords: Geohelminths, geophagia, health, microorganisms, soilAfrican Journal of Biotechnology Vol. 9(19), pp. 5784-5791, 10 May, 201

Physicochemical characteristics of geophagic clayey soils from South Africa and Swaziland

Physicochemical properties of geophagic clayey soils from South Africa and Swaziland were determined in order to appreciate their capability to perform the functions for which they are consumed and possible consequences of the practice in humans. Tests conducted included colour, texture, pH, electrical conductivity (EC), water retention capacity (WRC), organic matter (OM) content and cation exchange capacity (CEC). The colour of the clayey soils ranged from grey to red. The soils varied texturally from loam to clay and had pH values of between 5.0 and 7.4. Values obtained for EC and OM content were generally low but those for WRC of the clayey soils were above 50% for all samples. These clayey soils, due to their colour are inferred to contain different forms of iron oxide minerals including haematite and goethite, which may help alleviate symptoms of iron deficiency anaemia. Their relatively high WRC may increase their effectiveness in the absorption of moisture in the gastrointestinal tract and therefore confirms the possibility of using these clays in the treatment of diarrhoea.Keywords: Soil pH, texture, cation exchange capacity, diarrhoea, water retention capacityAfrican Journal of Biotechnology Vol. 9(36), pp. 5929-5937, 6 September, 201

Soil Heavy Metal Concentration Patterns at Two Speed Zones along the Gaborone- Tlokweng Border Post Highway, Southeast Botswana

Since 1988 Botswana has been experiencing an unprecedented increase in vehicular traffic which is suspected to be having contamination effects on soils along heavily used roads in the country. This study aimed atunderstanding the contamination trends of heavy metals on soils due to vehicular emissions. The soil physicochemistry (bulk density, particle size distribution, pH, electrical conductivity and cation exchange capacity),mineralogy (using x-ray diffraction techniques) and heavy metals (Cd, Pb, Cu and Zn) concentrations were determined for soil samples obtained along the roadside at 2m, 4m, 6m and 100 m of the Gaborone – TlokwengEmigration/Immigration Boarder Post Road, which is one of the busiest in the country. Bulk density of soil samples were from 1.19 to 1.4; and sand, loamy sand and sandy loam textural classes constituted the soil samples. The soil pH was from 5.09 to 8.57; the EC ranged from 6.27 ìS cm-1to 20.3 27 ìS cm-1 and the CEC values were from 10.2 meq100g-1 to 27.2 meq100g-1. Clay minerals were identified in the samples as well as feldspar and quartz. The concentration levels for Pb were from 0 mgkg-1 to 71 mgkg-1; Zn were from 5.23 mgkg-1 to 51.26 mgkg-1 ; Cu werefrom 0.3 mgkg-1 to 18.1 mgkg-1 and Cd 0 mgkg-1 to 2.4 mgkg-1 . The interplay of soil physico-chemistry and mineralogy on heavy metals concentrations is discussed. Although levels of heavy metals concentrations fell below normal ranges, the values obtained were generally higher than those from some developed and developing countries.@JASE