Some springs in Awing, North West Cameroon, were assessed in order to ascertain their quality for human consumption. Achialum, Meupi, and Ala'amiti quarters in Awing depend on springs as the major source of drinking water and inhabitants consume it in its natural state without prior assessment and treatment. Water samples were collected from Achialum, Meupi, and Ala'amiti and analysed for organoleptic, physicochemical, and bacteriological parameters using standard methods. Results of organoleptic and physicochemical parameters showed that most of the parameters fell below WHO limits. Water quality index results, based on physicochemical parameters only, showed that Achialum and Ala'amiti springs were of good quality while Meupi spring was of poor quality. Water quality index may not carry enough information about the real quality situation since a single bad parameter value can give misleading information about the water quality. However, the bacteriological aspect revealed the presence of faecal coliforms and pathogenic bacteria in all the springs that justified the high rate of water borne diseases recorded in the area. This poor water quality could be associated to poor hygiene and farming practices. Thus, the population of Awing should implement home water treatment methods such as boiling, filtration, or chlorination before consumption.

We lack an understanding of nitrogen (N) cycles in tropical forests of Africa, although the environmental conditions in this region, such as soil type, vegetation, and climate, are distinct when compared with other tropical forests. Herein, we simultaneously quantified N fluxes through precipitation, throughfall, and 0-, 15-, and 30-cm soil solutions, as well as litterfall, in two forests with different soil acidity (Ultisols at the MV village (exchangeable Al 3+ in 0-30 cm, 126 kmol c ha -1 ) and Oxisols at the AD village (exchangeable Al 3+ in 0-30 cm, 59.8 kmol c ha -1 )) over 2 years in Cameroon. The N fluxes to the O horizon via litterfall plus throughfall were similar for both sites (MV and AD, 243 and 273 kg N ha -1 yr -1 , respectively). Those values were remarkably large relative to other tropical forests, reflecting the dominance of legumes in this region. The total dissolved N flux from the O horizon at the MV was 28 kg N ha -1 yr -1 , while it was 127 kg N ha -1 yr -1 mainly as NO 3 --N (~80%) at the AD. The distinctly different pattern of N cycles could be caused by stronger soil acidity at the MV, which was considered to promote a superficial root mat formation in the O horizon despite the marked dry season (fine root biomass in the O horizon and its proportion to the 1-m-soil profile: 1.5 Mg ha -1 and 31% at the MV; 0.3 Mg ha -1 and 9% at the AD). Combined with the published data for N fluxes in tropical forests, we have shown that Oxisols, in combination with N-fixing species, have large N fluxes from the O horizon; meanwhile, Ultisols do not have large fluxes because of plant uptake through the root mat in the O horizon. Consequently, our results suggest that soil type can be a major factor influencing the pattern of N fluxes from the O horizon via the effects of soil acidity, thereby determining the contrasting plant-soil N cycles in the tropical forests of Africa. ARTICLE HISTORY

Soil water erosion is a major agricultural concern in tropical Africa with high precipitation and low soil fertility where Oxisols are generally distributed. A field experiment was conducted in east Cameroon during the rainy season in 2013 to investigate the effects of surface mulching with the residues of Imperata cylindrica on soil losses and surface runoff water generation in a cassava cropland on an Oxisol. Three treatments were established using two small plots for each treatment: bare plot (BA), cassava plot (CA) and cassava with mulch plot (CM). Soil loss and surface runoff water were measured, and water budgets of rainfall, surface runoff and soil moisture within rainfall events were measured in all treatment plots. Runoff coefficients in all treatment plots were suppressed below 8·0% because the large volume of large pores of surface soil of Oxisols contributed to the high drainage capacity over a rainy season even under wet soil moisture conditions. Total soil loss in CM was decreased by 49% compared with that in BA and CA, despite there not being a large difference in runoff water among treatments. These results suggest that surface mulching with the residues of I. cylindrica can substantially suppress soil losses caused by particle detachment by raindrops, while it maintain soil surface with originally high permeability in cassava croplands on Oxisols. Copyright © 2016 John Wiley & Sons, Ltd.

This research work was aimed to assess the quality of agricultural soils of Awing-North West Cameroon by elucidating some physicochemical properties and heavy metals in the soils. Agricultural yields in Awing have witnessed a decline in recent years and farmers have repeatedly used fertilizers to improve on their agricultural yields. It is thus important to test the soil in order to ensure not only high productivity but its quality as well and suggest methods to increase agricultural yields, while preventing soil and water pollution. Twenty soil samples were randomly collected from four sites, Achialum, Meupi, Nepele and Ala'amiti, in Awing and analysed for physicochemical and heavy metal properties using standard methods. Results showed that all the soils had low bulk densities (0.76-0.89 g cm -3 ), low pH values (4.1-6.0), low electrical conductivities (0.02 -0.11 mS cm -1 ), low available phosphorus (1.55-14.26 mg kg -1 ) and the soil textural class was dominated by loam. The mean available concentrations of heavy metals ranged from 0.24-2. 73, 0.64-5.13, 13.79-34.51, 29.45-92.27, 0.00-0.80, 0.24-4.54, 0.68-1.39, 0.30-0.47 mg kg -1 for Zn, Cu, Mn, Fe, Pb, Ni, Cr and Cd respectively. Results of heavy metal analysis showed that the soils were contaminated to different levels (above FAO/WHO limits) by the different heavy metals. Natural origins, fertilizer application and domestic waste were identified as the major sources of heavy metals in the soils. Future research should focus on the development of methods to quantify lime-enhanced mobilization of nutrient ions and lime-induced immobilization of heavy metals in these soils.

Micronutrient status of top soils (0 -25 cm) collected from intensively cultivated soils (typic dystrandept) in the Bambouto highland of Cameroon was investigated. Thirty-six soil samples were collected within a 100 m × 100 m grid. 16 of them were analyzed for pH, organic carbon, cation exchange capacity (CEC), Total N (totN), available P, exchangeable K, Ca and Mg, and 36 samples were analyzed for Cu, Mn, Fe and Zn. The status of trace elements was compared with soil critical levels and soil-based risk thresholds, and was declared deficient, sufficient or toxic. The soils were generally, slightly acidic, of high organic and nitrogen status and of adequate concentrations in exchangeable bases and available P. Mean values of Fe, Cu, Mn and Zn were 58.59, 0.52, 29.20 and 4.99 ppm, respectively. Relative to critical levels, 53% and 8% of the soils examined were deficient in Cu and Zn respectively while in all soils, Fe and Mn were above critical levels. The concentrations of the micronutrients investigated (except for Fe in 3% of the soils) were lower than toxic thresholds prescribed by European Economic Community (EEC) and the United States Environmental Protection Agency. Farmers' current level of agricultural intensification has no threats on micronutrient toxicity. However, because of Cu and Zn deficiency observed in some fields, an analysis of spatial variability is required to guide site specific soil nutrient management. Furthermore, in order to obtain quality produce and protect the environment, a balanced fertilizer recommendation including NPK + Cu + Zn is required for intensively cultivated typic dystrandept soils in the Bambouto highlands.