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Access to information on soil nutrients status and variability is essential in understanding the potential of soils and their responsiveness to management interventions in agriculture. The current study evaluated soil nutrients status in selected agroecological zones (AEZs) of Cameroon and identified variations and their adequacy for maize (Zea mays L.), sorghum (Sorghum bicolor L. (Moench)), and cassava (Manihot esculenta Crantz) production. A total of 163 soil samples were collected from surface (0–15 cm) layer for the determination of pH, organic matter (OM), estimated nitrogen release (ENR), sulphur (S), calcium (Ca), magnesium (Mg), potassium (K), sodium (Na), boron (B), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), aluminium (Al), phosphorus (P), total exchangeable capacity (TEC), and base saturations. The results showed different degrees of variability in soil nutrients ranging from low to very high in all the AEZs. The soils in all the AEZs were consistently deficient in available phosphorus, sulphur, boron, and zinc in varying proportion and might be inadequate to supply cultivated maize, sorghum, and cassava with the nutrients needed to achieve optimal growth. The soils were also prone to Mg-induced K deficiency, which could limit the growth of maize, sorghum, or cassava. These results therefore suggest that management of inherent soil properties should be based on-site specific situations.

Assessment of genotypic and phenotypic diversity of the rain-fed Sorghum in the sahelian zone of Cameroon. Objectives: This study was conducted to determine the genotypic and phenotypic diversity in the accession of the rain-fed Sorghum in the sahelian zone of Cameroon and to estimate the genetic parameters, which can be used to create new varieties of Sorghum in Cameroon. Methodology and results: Forty-four (44) accessions were grown in a randomized complete bloc design with three replications. The results showed there was a large morphological diversity among the Sorghum accessions. Furthermore, these diversities were organized around vegetative and yield characters, which divided the accessions into three groups. The individual in group three (3) showed interesting performance in term of plant height and grain yield parameters. The analysis of genotypic and phenotypic parameters showed that there was low influence of the environmental factors on the performances of the accessions. Conclusions applications of findings : There was a the low difference between the phenotypic and genotypic variances for all characters. High broad sense heritability estimates recorded for all characters and the expected genetic advance were variables. The high expected genetic advance observed in the vegetative characters are better in the yield characters. The results from this study provide useful information in selection of parents that breeders could exploit in sorghum improvement program in Cameroon.

In the present study, two topomorphic vertisols profiles used for sorghum production were described and characterized. After macroscopic characterization, physicochemical, mineralogical and geochemical analyses were made. Physicochemical analyses were made by standard methods while mineralogy was determined on clay fraction (˂2µm) by X-ray diffraction coupled to Fourier transform infrared spectroscopy. Geochemical analysis was determined on 180µm fraction by inductively coupled plasma-Atomic Emission Spectroscopy (ICP-AES) and mass spectrometry (ICP-MS). Results revealed that studied vertisols were average deep, less differentiated with desiccations cracks and gilgai micro relief. The angular blocky structure and clayey texture were observed. They were alkaline (7.3 ≤ pHwater ≤ 8.4) and recorded a low to moderate organic matter and nitrogen contents. Cation exchange capacity was high reaching 52.24 meq 100g-1 and exchangeable cations were moderates with Ca 2+ (3.69-29.6 meq 100g-1) the most represented cation. Vertisols were made of smectites associated to kaolinite and a lesser content of quartz. Illites and calcite were also identified in some horizons. On the geochemical point of view, Si02 (55.87-83.64%), Al2O3 (6.08-20.25%), Fe2O3 (2.09-6.39%) and K2O (1.43-2.24 %) were the dominant oxides. Traces elements were represented essentially by Ba (518-1202 mg kg-1), Zr (334-685 mg kg-1) and Sr (71-190 mg kg-1). The overall features are suitable to dry season sorghum production. The amount of smectites seemed to be an important factor affecting their water holding capacity on which dry season sorghum production depends. Improved cropping systems have to be developed to sustain productivity in vertisols with low smectites and where annual rainfall is lesser.

The study of the soils from Mbé and Wack is carried out in the framework of the knowledge of soils from the Adamawa Region of Cameroon and their erodibility was investigated using erodibility indices obtained through physico-chemical data. Eleven topsoils (0 -20 cm) samples were collected on different land use and their susceptibility to erosion was assessed. The water dispersible clay (34.92 -121.75 g•kg −1 ), the clay dispersion ratio (0.45 -0.84) and the dispersion ratio (0.75 -0.89) were high in the studied soils while the clay aggregation (13.16 -42.27g•kg −1 ) and the clay flocculation index (0.16 -0.55) were low to moderate indicating their high erodibility. The soils under natural vegetation, more clayey, displayed the highest amount of water dispersible clay while cropped soils recorded the smaller ones. Globally, in cropped soils, those under cereals displayed the highest clay dispersion indices than those under tubers. This suggests that tubers cropping practices in studied soils enhance their erodibility. Statistical analyses revealed that amorphous Al and Fe are elements which limit soils erodibility while K + and 4 NH + promote soils particles dispersion. Sustainable management of these soils will consist on limiting runoff through agricultural practices such as direct seedling and orienting tillage perpendicularly to slope gradient.

The discovery of new ecological fertilizers can sustainably enhance plants nutrition. In that point of view, the present study aimed to demonstrate the high concentration of water from cooked beans in organic compounds, various mineral salts and water. For that purpose, moulds were used because of the above listed elements as their basic feeding needs. Cold water from cooked beans was collected and kept during five days at open-air; the evolution of its aspect was daily followed up. The experimental design was a randomized complete block in 10 replicates; an eleventh bucket filled with the same water was used to perform some of its characterization. The moulds are Aspergillus L. The water from cooked beans is a heterogeneous mixture and particularly a globular proteic suspension. At rest, it organizes itself in a superficial flaky domain and a lower liquid domain. The flaky domain is mainly organic and the liquid domain is mainly both mineral and aqueous. The density of the flaky domain was 0.964 and that of the aqueous domain was1.011. The average speed of the growth of Aspergillus L. at the surface of the water from cooked beans was 3,17 cm2/H; they cover then in five days a surface of 379.74 cm2. The exponential growth of Aspergillus L. at the surface of the water from cooked beans generated a continuous decreasing of the pH; this behavior shows that the water from cooked beans seems to be an adequate substrate; it then implicitly contains all the nutrients required for their optimal development; this include water, organic matters and mineral salts among which nitrogen, potassium, phosphorus, sulfur and calcium can be named; it is then a complete liquid organic fertilizer. That water appears also as a high grade activator for soils micro flora. Peasants could thus save a lot of money by using this liquid single or in combination with other fertilizers to promote the sustainable development of agriculture in their ecosystems.

Abstract. Research carried out on soil organic carbon stock (SOCS) in the Sudano-Sahelian region of Cameroon is very rare. The few existing studies are mostly available in reports and concern in most cases carbon stocks in plant biomass. In order to contribute to the documentation on soils in this part of the country, the present work was designed to evaluate the SOCS in the main soil types and the influence of environmental factors and soil properties on these stocks under the natural dry tropical area of the Sudano-Sahelian zone of Cameroon. The study was undertaken in four sites, including three natural forest reserves (Laf, Zamai, Kosohon) and one national park (Mozogo), located at different latitudes. Three replicates were collected at each site, giving rise to three sampling points chosen per site, from 0 to 75 cm depth, for the determination of SOCS. At each sampling point, soils were sampled using depth increments of 25 cm from the surface. The studied area is covered by Haplic Vertisols, Dystric Arenosols, Dystric Leptosols and Dystric Planosols. Total SOCS (T-SOCS) content, which refers to a depth of 75 cm, decreases with increasing latitude, with 249±26.26 Mg ha−1 in Vertisols at Laf forest reserve most southerly located, 199±8.00 Mg ha−1 in Arenosols at Zamai forest reserve, 166±16.63 Mg ha−1 in Leptosols at Kosohon forest reserve and 161±8.88 Mg ha−1 in Planosols at Mozogo national park most northerly located, regardless of the altitude. No significant correlation was noted between T-SOCS and the altitude. A good correlation was noted between precipitation which decreases with increasing latitude and T-SOCS, indicating the importance of climate in the distribution of T-SOCS in the study area, which directly influences the productivity of the vegetation. More than 60 % of the SOCS was stored below the first 25 cm from the soil surface, a peculiarity of SOCS in drylands. The SOCS in the Sudano-Sahelian area of Cameroon is mainly influenced by climate and vegetation.