In Cameroon, the noctuid Busseola fusca is the most important pest of maize. The braconid Cotesia sesamiae, which is the most common larval parasitoid of noctuid stemborers in eastern Africa, was absent on B. fusca attacking maize. Thus, it is planned to introduce several strains of the parasitoid from Kenya. Pre-release surveys were undertaken in major maize growing areas to catalogue stemborer species, and larval and pupal parasitoids on maize and four wild host plant species. On maize, B. fusca was the predominant borer in all ecozones except for the lowland coastal forest, usually accounting for 60-99%, followed by the pyralid Eldana saccharina in the forest zone and the crambid Chilo sp. in the mid-altitudes. Contrary to what was reported before, the noctuid Poeonoma serrata -and not B. fusca -was the predominant borer on elephant grass, constituting 70-96% of all borers. On wild sorghum in the forest zone, the noctuid Sesamia poephaga was the most abundant species, while on Panicum sp., Chilo sp. predominated. On Setaria megaphylla in the forest zone, Chilo sp. was the most abundant species followed by Busseola quadrata. Busseola fusca was scarce on all wild grass species, indicating that previous reports on the predominance of this pest species on wild host plants were the result of misidentifications. Three tachinid and 16 hymenopteran parasitoids were obtained, most of them from B. fusca and P. serrata, on maize and Pennisetum purpureum respectively. C. sesamiae was scarce and never recovered from B. fusca on maize. In view of the new findings, acceptability and suitability studies involving the different stemborer species identified from wild plant hosts are required to determine if they will form a reproductive sink or perennate C. sesamiae populations during the off-season when maize is scarce and B. fusca is diapausing.
Struvite, from human urine, is an alternative phosphorus (P) fertilizer. This study evaluated P release from struvite and its effectiveness for maize in Inanda (Ia), Sepane (Se) and Cartref (Cf) soils. Phosphorus sorption isotherms were determined, an incubation study determined the release pattern of P from struvite, and a pot trial compared struvite with single superphosphate (SSP) on maize P uptake. The amount of P at equilibrium (where Q = 0) in the Cf was 1.39 mg L , respectively. The extractable P in all three soils increased with time, with evidence of declining P release after Day 8. Struvite was most effective as a P source in the Cf followed by Se and Ia. Compared to SSP, there was significant improvement in maize grown on the Cf, while the reverse occurred in the Se. Maize grown in the Ia did not respond to either struvite or SSP. It was concluded that the phosphorus sorption was the main limiting factor that governed struvite effectiveness as a P source.
The disposal of treated wastewater from an anaerobic baffled reactor (ABR) effluent into water bodies can cause pollution. Treated wastewater management through irrigation of crops has the potential of increasing crop production through nutrient uptake while reducing the risks of environmental pollution. However, this study aimed to investigate the effect of irrigation with ABR effluent on Swiss chard yield, nutrient (N and P) uptake and leaching. Field experiments were done over three seasons at Newlands, Durban, South Africa. The experiments were laid out in a randomised complete block design with three treatments: ABR effluent irrigation (ABR), tap water irrigation with fertiliser (TWF) and rain-fed with fertiliser (RFF). Data were collected on nutrient (N and P) leaching at 30 and 50 cm depths, crop growth, soil chemical properties and nutrient uptake.Effects of irrigation with ABR effluent on soil chemical properties, Swiss chard growth, plant nutrient uptake and leaching were comparable to TWF and RFF treatments. This implies that irrigating crops with ABR effluent is a potential method for wastewater management in a manner that will not cause environmental pollution while benefiting peri-urban farmers.
In urban areas, human activities result in the discharge of a variety of chemical substances into the environment. This affects soil quality, plant species diversity and human security. To suggest appropriate management strategies that ensure soil quality and human security amid urbanization, this study assessed the relationship between macrophyte diversity and some soil characteristics of wetlands that are adjacent to urban, peri-urban and rural areas in Bamenda Municipality, Cameroon. Plant communities were sampled for species composition and relative abundance, using the Braun-banquet method. Species richness was evaluated using Simpson’s diversity index. Twenty-one soil samples (0–25 cm depth) were randomly collected within the wetlands and analyzed for their physicochemical characteristics using standard methods. The hierarchical cluster analysis (HCA) was used to group the wetlands under managing units. The dominant species ranked in order of abundance in the rural wetland were Raphia farinifera > Ludwigia hexandra > Coix spp. > Leersia hexandra > Ehchinochloa paramidelis. The Peri-urban wetland dominant species stood at Commelina bengalensis > Leersia hexandra > Cyperus distance > Ehchinochloa pyramidalis. In the Urban segment, Pennisetum purpureum > Echinochloa pyramidalis > Tithonia diversifolia > Leersia hexandra were the abundant species. The Simpson index of diversity was 0.94 for the urban and 0.96 for the peri-urban and rural sites respectively. The soils were slightly acidic with pH KCl ranging from 4.87 to 5.41. From the coefficient of variability classes, Sand, pH-H2O, pH-KCl, and Na consistently varied slightly across the three sites. Two significant clusters (management units) representing a combination of urban, and peri-urban/rural were formed from the hierarchical dendrograms. The Mann–Whitney U test revealed a significant (P < 0.05) lower exchange acidity in the rural than the urban sites indicating contamination of the urban site, reducing its macrophyte diversity. Intensification and extension of urbanisation are gradually reducing the macrophyte diversity and also contaminating the soils of the wetlands of the Bamenda municipality in Cameroon, warranting monitoring. The chemical composition of soils in the urban cluster needs early remediation by encouraging the planting and monitoring of certain plants that can already take up the elements.
The physicochemical properties of soils within the Mount Cameroon region are constantly changing due to their altitudinal gradient and diverse land-use systems. This modification poses a threat to the inhabitants of this area as their livelihood depends on these soils. Information about an impact of altitude and land-use systems on soil physicochemical properties in the eastern flank of Mount Cameroon is scanty and needs investigation. Soil samples, collected from different land-use systems along altitudinal gradients within the Buea zone (older lava flow) and Ekona zone (20th century lava flow), were analysed for their physicochemical properties using standard methods. The relationships among soil properties; altitude and land-use systems were established using correlation analysis and the analysis of variance (ANOVA). Sand and clay varied significantly (p<0.05) with altitude. Soils under mixed cropping with legumes had the highest pH values while those under mixed cropping without legumes had the lowest pH values. Calcium (Ca2+) and magnesium (Mg2+) dominated the exchange complex. Total nitrogen (N) and organic carbon (OC) ranged from 0.18 % and 1.50 %, respectively in soils under mixed cropping without legumes to 0.81 % and 6.55 %, respectively in soils under fallow land. There were significant (p<0.05) positive correlations between pH and Ca2+, pH and effective cation exchange capacity (ECEC), pH and moisture content (MC), and Ca2+ and MC. Soils from the Ekona zone located at the leeward side of the mountain and receiving more essential nutrients from the weathering of the young lava flow had a better-quality potential compared to soils from the Buea zone located at the foot of an older lava flow. The Ekona zone could be harnessed for extensive agricultural activities. Management practices should therefore take into account all cultural practices, which enrich soils for sustainable crop production and soil maintenance.
AimsIn urban areas, human activities result to the discharge of a variety of chemical substances to the environment, playing a substantial role in soil quality, plant species diversity and human security. In order to suggest appropriate management strategies that ensures soil quality, their sustainable utilization and human security in the midst of urbanization, this study assesses the relationship between macrophyte diversity and some soil characteristics of wetlands in Bamenda Municipality, Cameroon at different stages of urbanization. It examines (i) macrophyte diversity and soil characteristics of wetlands adjacent urban and peri-urban areas. MethodsPlant communities were sampled for species composition and relative abundance, using the Braun-banquet method. Species richness was evaluated using the Simpson’s diversity index. Twenty-one soil samples (0 - 25 cm depth) were also randomly collected within the wetlands and analyzed for their physico-chemical characteristics using standard methods. The hierarchical cluster analysis (HCA) was used to group the area under managing units. ResultsFrom the results, 50 macrophytes species distributed in 28 families were documented in the area. The species observed were mostly emergent herbaceous plants (grasses) with only few shrubs and trees. The Simpson indices of diversity were 0.94 and 0.96 for the urban and control sites, respectively. The soils were slightly acidic. Sand, pH-H2O, pH-KCl, Na were consistently least variable across the three sites. Two significant clusters representing a combination of urban and peri urban/rural were formed from the hierarchical dendrograms for classification of the chemical variables for the surface soils wetlands with associations to plants species. The Mann-Whitney U test, revealed a significant lower (P <0.05) concentration of the chemical constituents of the control site and the urban sites indicating contamination.ConclusionIntensification and extension of urbanisation is reducing the diversity of the wetlands of the Bamenda municipality warranting monitoring.
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