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

Physico-chemical, mineralogical and chemical considerations in understanding the 2001 Mabeta New Layout landslide, Cameroon

Landslides are part of natural catastrophic disasters destroying both biological and physical entities including loss of human lives. An evaluation of soil properties involved in landslides is significant in itsmanagement. To this effect, soil samples from the 2001 landslide occurrences in the Mabeta New Layout, Limbe, Cameroon were analysed using standard techniques to determine texture, pH, electrical conductivity (EC), bulk density (Db), water absorption percent (WA), linear shrinkage, plasticity index (PI), loss-on-ignition (LOI),mineral content and major cations. Results obtained were: bulk density (0.89 – 1.08 g/cm3), LOI (19.4 - 25.7%), water absorption (23.4 – 29.1%), linear shrinkage (5.4 – 8.3%), volume shrinkage (4.8 – 8.5%), PI (13.5 –20.75%), major cations ((Fe2O3 : 9.91 – 23.24%), (Al2O3 : 9.88 – 28.48%), (CaO : 0.73 – 1.3%), (MgO : 0.55 –2.80%), (K2O : 1.06 – 1.59%), (Na2O : 0.77 – 0.89%)), pH (5.17 – 6.90) and EC (16.53 – 149.20ìS/cm). Values from physico-chemical analyses, secondary minerals abundance index (SMAI) and chemical index of alteration (CIA) of the soils were reflective of particles with high potential for sliding. With major contributions from favourable slope, seismic and hydrologic forces, the event occurred

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