The effect of crude oil pollution on heavy metal content in the soil, microbial population, and growth performance of maize and cowpea was investigated. The heavy metals determined were lead, cadmium, iron, nickel, zinc and copper. Microbial population and growth performance of maize and cowpea in both polluted and unpolluted soils samples were evaluated. Results showed that higher concentration of heavy metals was observed in all crops planted in polluted soil, polluted site vegetation and soils. The total heterotrophic bacteria was 89% lower in the polluted soil than in the unpolluted soil while fungi was 78% lower in the polluted soil when compared to the unpolluted soil. However, hydrocarbon utilizing bacteria and fungi was 22% and 24% higher in the polluted soil than in the unpolluted soil respectively. Maize and Cowpea performed poorly in polluted soil when compared with unpolluted soil as evidenced in the growth parameters measured for both crops.
This study examined microbial population (MP) and heavy metal load in the soil and mango leaf, along Ogbomoso-Oyo road (high traffic density) and Ogbomoso-Ifeodan (low traffic density). Mango leaves (about 3m from the ground) were sampled at three spots (10km intervals) and three distances of 0-10, 10-20 and 20-30m from the edge of the road. Soil was sampled at 0-15 and 15-30cm depth under mango trees. The samples were analyzed for Pb, Cd, Cr, Zn with atomic absorption spectrophotometer and total MP using nutrient media preparations. On the High Traffic Density (HTD) road, 20-30m distance, the soil contained higher amount of Lead (7.71±0.76), Cadmium (8.36±0.59), Chromium (0.48±0.02) and Zinc (5.58±0.37mg/kg). MP was higher at 0-10m with Total microbial count of 10.5±1.46×10 5 Cfug-1 and Total fungi count of 0.83±0.23×10 5 Cfug-1. Microbial population was higher along LTD than HTD road. Mango leaf contained significantly higher metal content along HTD road Pb (4.31), Cd (4.63), Cr (0.03) and Zn (5.04mg/kg) than LTD road. Microbial population was higher at LTD than HTD, and Mango accumulated higher heavy metals at HTD than LTD. Implications of heavy metals and microbial populations on food chain were discussed.
ABSTRACT.A field work was carried out to investigate the extent to which selected soil chemical properties can influence weed species distribution. There were sixteen treatments of two factors (Fertilizer type and weeding regimes) laid out in RCBD. The treatments included four fertilizer types; no fertilizer (F1), inorganic fertilizer -NPK 15:15:15 applied at 100 kg NPK/ha (F2), organic fertilizer -phosphocompost applied at 2.5 t/ha and organomineral -50% NPK 15:15:15 plus 50% phosphocompost. Four weeding regimes: weedy treatment (W1), weeding once (W2), weeding twice (W3) and weed free (W4). Weed free and weed once significantly improved maize growth and yield parameter under inorganic and organomineral fertilizer types. Increasing soil pH, organic carbon and available phosphorus significantly reduced total weed biomass with plot that received no fertilizer been responsible for highest weed population. In organic fertilizer treatment significantly reduced soil pH from the initial 6.5 to 6.0 though, it combination with weed once or weed twice gave highest grain yield. Better nutrition (in terms of improved soil nutrient especially macro nutrient and organic carbon) when combined with weeding once can ascertain proper weed management and sustainable maize production. INTRODUCTIONThere are innumerable reports on the inhibitory effects of weeds on crop plants [1] and weeds can cause crop yield reduction up to 90% [2] Weeds compete with crops for nutrients, sunlight and other essential components in the environment required for good crop development and lead to yield reduction of the choice crop plant [3].A total of 263 weed species belonging to 38 families were found in crop fields in West Africa. Broad-leaved weeds (72%) and grasses (24%) dominated the total weed spectrum, whereas sedges (4%) were minor, weed species richness per field was similar across all agroecological zones and averaged about 16 per field [4]. Unweeded fields in Nigeria produced between 17 and 30 tons per hectare of fresh weed weight [5]. Weeds cause about $36 billion annual damage in the United States alone, unchecked, weeds effectively outcompete crops for resources and decrease the yield of food, feed, and fiber [6]. Weeds are persistent, adaptable, stress tolerant, competitive, and capable of extreme levels of reproduction More than 400 biotypes of weeds have evolved resistance to one or more of all the major groups of herbicides [7].A good understanding of how plants alter the soil ecosystem is critical to the management of crop-weed interactions and the consequent impacts of weed management practices on soil quality. Weeds are often perceived as exerting only negative effects on crop growth through competition for limiting soil nutrients, water, and light, thus necessitating management practices aimed at reducing these effects. While there is ample evidence to support this perception [8], there is also an increasing body of theory [9] and experimental evidence [10] suggesting that the specific characteristics of the weed community (i.e....
A field work was carried out to investigate the extent to which selected soil chemical properties can influence weed species distribution. There were sixteen treatments of two factors (Fertilizer type and weeding regimes) laid out in RCBD. The treatments included four fertilizer types; no fertilizer (F1), inorganic fertilizer – NPK 15:15:15 applied at 100 kg NPK/ha (F2), organic fertilizer – phosphocompost applied at 2.5 t/ha and organomineral – 50% NPK 15:15:15 plus 50% phosphocompost. Four weeding regimes: weedy treatment (W1), weeding once (W2), weeding twice (W3) and weed free (W4). Weed free and weed once significantly improved maize growth and yield parameter under inorganic and organomineral fertilizer types. Increasing soil pH, organic carbon and available phosphorus significantly reduced total weed biomass with plot that received no fertilizer been responsible for highest weed population. In organic fertilizer treatment significantly reduced soil pH from the initial 6.5 to 6.0 though, it combination with weed once or weed twice gave highest grain yield. Better nutrition (in terms of improved soil nutrient especially macro nutrient and organic carbon) when combined with weeding once can ascertain proper weed management and sustainable maize production.
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