Effects of Chromolaena and Tithonia Mulches on Soil Properties, Leaf Nutrient Composition, Growth and Yam Yield

Plant materials differ in their chemical composition, rate of decomposition and suitability as mulch materials. Experiments were conducted on an Oxic Tropuldalf of southwestern Nigeria at Owo to study the effect of Chromolaena and Tithonia mulches applied at 0.0, 5.0, 7.5, 10.0 and 12.5 t ha-1 on soil chemical properties, leaf nutrient composition, growth and tuber yield of white yam (Dioscorea rotundata Poir). Both Chromolaena and Tithonia mulches reduced soil bulk density and temperature. They also increased concentrations of organic matter, N, P, K, Ca and Mg in the soil, and N, P, K, Ca and Mg in the leaves. The mulches also increased growth and yield of yam compared with the control. The values of soil organic matter, N and P, and leaf N and P concentrations increased with increasing mulch rate. Chromolaena mulch and Tithonia mulch applied at 10.0 and 7.5 t ha-1, respectively, were found to be suitable for yam production. Tithonia mulch compared with Chromolaena mulch produced higher values of soil chemical properties, leaf nutrient concentrations, growth and yield of yam. Tithonia mulch produced 19% and 18% higher tuber yield compared with Chromolaena mulch in the first and second cropping seasons, respectively

Carbon Monoxide as Indoor Pollutant in Kano Metropolis

The level of carbon monoxide concentrations in three different residential areas of Kano municipality has been determined. Health effects of carbon monoxide are not only determined by its pollution level, but the time spent breathing polluted air. Samples of carbon monoxide gas in three different residential districts within the Kano Metropolis; the high (city), medium (Sabon gari) and low (Nassarawa) density residential districts were assessed. The frequency distribution pattern for the gas is skewed towards high frequency of low concentration with a mean and standard deviation of 4.93 ± 3.08ìg/m3. Evidence linking high level of indoor carbon monoxide tolow birth weight and increase in prenatal deaths necessitates the need to periodically check the levels of the gas within each house hold in the metropoli

An Assessment of the Levels of Heavy Metals, Nitrates and Nitrites in Three Leafy Vegetables from Selected Rural and Urban Markets in Kwara State, Nigeria

The concentration of some heavy metals, nitrates and nitrites in leafy vegetables sold in selected markets in Ilorin and its environment were investigated. Three leafy vegetables (Amaranthus hybridus, Celosia argentea and Corchorus olitorious) were used in this study. The concentration of selected heavy metals (cadmium, lead, copper, zinc and arsenic), nitrates and nitrites in the leaves were analyzed using standard methods and compared with the permissible limits recommended by the Food and Agricultural Organization (FAO)/WHO Expert Committee on food additives. The concentration of cadmium was significantly higher than the permissible limits (0.20 mg/kg) for all the vegetable types across locations. However, the concentrations of lead, copper, zinc and arsenic which ranged from 0.06 to 0.13 mg/kg, 0.09 to 0.18 mg/kg, 0.05 to 0.16 mg/kg and 0.08 to 0.17 mg/kg were lower than the permissible limits for all the vegetables and in all locations. The concentration of nitrates in the leafy vegetables ranged from 0.09 to 0.37 mg/kg and was within the safe limit (< 3.70 mg/kg) as recommended by (FAO)/WHO Expert Committee on food additives while nitrite was not detected. In conclusion, monitoring of vegetables for toxic heavy metals is essential for food safety in Nigeria. Although lead and arsenic were below safe limits they have the tendency to accumulate to toxic level in consumers. There is the need to increase the essential micronutrient content of soils around the study area given the low concentration of Cu and Zn in the leafy vegetables.Keywords: Food safety, toxicity, micronutrients and concentrations