Effect of substrates on germination and seedling emergence of sunflower (Helianthus annuus L.) at the Yongka Western Highlands Research/Garden Park, Bamenda-Cameroon

A study was carried out at the Yongka Western Highlands Research Garden Park, Nkwen­Bamenda in Cameroon to evaluate the effect of substrates on the germination and seedling emergence of sunflower (Helianthus annuus L.). Seeds of African Giant variety were used with six substrate media (sawdust, sand, soil, sawdust­sand, sawdust­soil and sand­soil). The experiment was laid out in a Randomized Complete Block Design in three replications. Germinated seeds were counted daily for a 15 days period. To estimate seedling emergence from two Weeks After Sowing (WAS) up to four WAS, data on seedling height and number of leaves were recorded. The results showed that germination started 8 days after sowing for all substrates. Germination rate was significantly affected by the substrates but the rates were less than 80%. The highest germination rate was recorded on the soil substrate (75%) while the lowest rate (25%) was recorded on the sawdust substrate. Seedlings on the sawdust substrate were also less vigorous and had less leaves (12.67 cm height and 4.7 leaves) than those on other substrates at four WAS (50–63 cm and 12.6–15.3 leaves). Based on the results, it is recommendable to use the soil substrate to nurse African Giant seeds

Geotechnical and physico chemical properties of clays associated with landslides in volcanic and metamorphic terrains in Cameroon, Central Africa

Comparative studies of geotechnical properties of soils from landslide scars within volcanic rocks in Alou Sub-Division located in the Bambouto caldera and from a major landslide scar within Precambrian metamorphic rocks (gneisses and granites) located at Kekem indicated a range of bulk densities of 0.93 to 1.12 g/ml and water content from 27 to 44% from the volcanic terrains while bulk densities and water content in the metamorphic rocks ranged from 1.14 to 1.52 g/ml and 7 to 35% respectively. Granulometric analyses based on the determination of Atterberg's limits indicated the predominance of silts of high plasticity in both areasalthough the proportion of the fine fraction (clay, silt and fine sand) was generally higher in the volcanic rocks. Mineralogical properties obtained from X-ray diffraction (XRD) patterns indicated the predominance of feldspars, chiefly microcline and gibbsite, with appreciable proportions of clays (montmorillonite, kaolinite, goethite, chlorite and halloysite) within the volcanic rocks while the gneisses were dominated by quartz and muscovite with some proportions of montmorillonite, kaolinite and feldspars with the clay fractions being more variable in the volcanic rocks (13 to 44%) than in the metamorphic rocks (23 to 29%). The presence ofmontmorillonite, a type of clay which has the ability to absorb water and swell, is an indication of a major contributor to the susceptibility of both terrains to sliding when subjected to high rainfall. This was revealed by data on intense precipitation during the specific months of the landslide events which led to elevated groundwater levels with raised pore water pressure in the highly weathered and loose materials resulting in increased shear stress and reduced shear strength with the eventual failures of the slopes causing the landslide disasters witnessed in both geological terrains.Keywords: Landslide scars, geotechnical properties, montmorillonite, Cameroon Volcanic Line, metamorphic rocks, high rainfall

Réponse de deux variétés de tournesol (Helianthus sp.) à la fertilisation à base de fiente de poule sur un Hapli-Humic Ferralsol du Yongka Western Highlands Research Garden Park (YWHRGP) Nkwen-Bamenda, Cameroun, Afrique centrale

Response of Two Sunflower (Helianthus sp.) Varieties to Poultry Manure Fertilization on a Hapli-Humic Ferralsol at the Yongka Western Highlands Research Garden-Park (YWHRGP) Nkwen-Bamenda, Cameroon, Central Africa. An experiment on a Hapli-Humic Ferralsol was conducted at the YWHRGP, Nkwen-Bamenda, to evaluate the response of two sunflower varieties (Helianthus sp.) to five levels of poultry manure (0; 1.2; 2.8; 4.2 and 5.6 Tons/ha). Italian White and African Giant varieties were used. The experiment was laid out in a randomized complete block design with three and six replications for African Giant and Italian White varieties, respectively. Poultry manure was analyzed and growth, development and yield parameters were collected. The acid soil (pH≤5.5) showed nutrient deficiencies. The poultry manure (pH=7.8) is rich in essential nutrients and had a significant effect on sunflower growth parameters. The 4.2 Tons/ha manure level maximised growth and yield parameters of the African Giant variety. For the Italian White variety, 5.6 Tons/ha manure level gave a head weight yield (0.74 Tons/ha) lower than that of the African Giant (1.33 Tons/ha). Significant differences were also observed between the two varieties. However, the African Giant variety appears to be more adapted for seed production, while the Italian White variety appears to be best indicated for use as an ornamental plant or to produce cut flowers

Use of Correlation Relationships to Enhance Understanding of Pedogenic Processes and Use Potential of Vertisols and Vertic Inceptisols of the Bale Mountain Area of Ethiopia

Five Vertisols and two Vertic Inceptisols developed from basalt and alluvial materials were characterized for physical and chemical properties. Correlative statistical relationships were established among physical and chemical properties including cation exchange capacity (CEC), percent total clay, electrical conductivity (EC), base saturation % (BS), pH-H2O, pH-KCl, CaCO3 equivalent, organic carbon (OC), total nitrogen (TN), P-Bray and P-Olsen. Correlative relationships were established among parameters for all horizons of the soils studied as well as among parameters within individual horizons. P-Olsen was highly correlated with OC and TN; simple coefficients of determination (r2) were 0.81 and 0.69, respectively. CaCO3 was highly correlated with pH-H2O and pH-KCl; r2 values were 0.68 and 0.60, respectively. Similar correlations were obtained for pHKCl vs pH-H2O and pH-KCl vs EC, with r2 values of 0.92 and 0.70, respectively. Total nitrogen was also very highly correlated with OC (r2= 0.88). Base saturation was highly correlated with pH-KCl and pH-H2O giving r2 values of 0.62 and 0.64, respectively. When correlative relationships were carried out among parameters within individual horizons very high correlation coefficients were obtained for OC vs TN (r= 0.98 - 1.00), OC vs P-Olsen (r= 0.96 - 0.99), BS vs pH-KCl (r= 0.82 - 1.00), BS vs pH-H2O (r= 0.86 - 1.00). Most of the simple correlation coefficients obtained for EC with pH-KCl and pH-H2O were > 0.81. High correlation coefficients (0.80 - 1.00) were obtained for % clay vs total CEC for most soils studied. Regression relationships developed constitute useful predictive indices for estimating agronomic properties from existing physical and chemical data and soil survey reports of the Bale Mountain area of Ethiopia. This study has demonstrated that statistical correlation can be used to cross-check the quality of analytical data both among horizons of different soil profiles and within individual soil profiles from prior established relationships