Browsing by Author "Amara, Denis Magnus Ken"

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Effect of Land Uses on Soil Erodibility in the Njala Area of Southern Sierra Leone
(Scientific Research Publishing, 2022) Amara, Denis Magnus Ken
Soil loss through erosion continues to pose serious challenges to increasing the smallholder agricultural productivity in Sierra Leone. While emphasis on sustainable land use practices continue to gain attention among land users, however, the rate of adoption among smallholder farmers is still very low and hence, in most part of the country soil fertility has been declining at alarming rates. In the Njala area, studies have shown that soil loss ranges from moderate to high. Though soil erosion has been identified as a major soil fertility declining factor, however, the effect of land use practices on the inherent resistance of soil materials to erosion is lacking. This study was therefore conducted to assess the effect of land uses on soil erodibility. The results showed that the soils are coarse sandy loam with high sand content. The dispersion ratios and erosion indices of soils under cassava, plantain, maize and guava were above the minimum thresholds of 15.0 and 10.0 respectively, thus indicating that these soils are highly erodible compared to soils under fallow and sweet potato which have dispersion ratios and erosion indices below the minimum thresholds. Clay content was inversely proportional to and significantly correlated with dispersion ratio and erosion index while the correlations between silt + clay, dispersion ration and erosion index, and silt, silt + clay and dispersion ratio were negative and non-significant. Considering the coarse nature of soils, landscape features and high erodibility indices, these soils would need special soil and water conservation practices to counter further degradation. These may include following, agroforestry, silvi-pasture, controlled and rotational grazing. In addition, awareness of sense of self-responsibility and forest policies and regulations are needed.
Land Suitability Assessment for Maize and Paddy Production in Bogur Microwatershed Using Remote Sensing and GIS Techniques
(Infogain Publication, 2016) Amara, Denis Magnus Ken
˗˗˗˗The main aim of this study was to assess the soils of Bogur microwatershed in Northern Transition Zone of Karnataka for sustainable production of maize and paddy.Seven land qualities including water availability index (W), oxygen availability (O), nutrient availability index (NAI), water retention (I), rooting conditions (R), excess of salts (Sa) and topography (T) were selected and their suitability evaluated.Four soils series: Singhanhalli, Bogur, Mugli and Venkatapur and seventeen soil units including SGH-c-d4-Be1 belonging to Singhanhalli series; MGL-cl-d3-De2 belonging to Mugli series; BGR1-sl-d4-Ce2, BGR2-c-d5-Be1, BGR3-sl-d4-Ce3 and BGR4-cl-d5-Ce2 belonging to Bogur series; and VKP1-sc-d4-Ce2, VKP2-sl-d3-Ee4, VKP3-c-d5-Be1, VKP4-sl-d2-Be1, VKP5scl-d4-De3, VKP5-scl-d3-De2, Vkp5-scl-d4-Be2, VKP5-scl-d3-Ce2, VKP6-cl-d4-Ce2, VKP7-sl-d2-De3, and VKP8-sl-d4-De3 belonging to Venkatapur series, were identified.Singhanhalli series covers 78.5 ha (10.3%);Mugli series covers 22.1 ha (2.9%); Bogur series covers 237.3 ha (31.2%); and Venkatapur series covers 406.6 ha (53.5%).One mapping unit, VKP2-sl-d3-Ee4 which accounts for 10.2 ha (1.3%) of the study area, was not evaluated for crop production because it is a non-cultivable land.The results revealed that 33.8 ha (4.4%) is moderately suitable, 312.7 ha (41.1%) is marginally suitable and 387.7 ha (51%) is not suitable for maize; whereas for paddy, all sixteen mapping units which account for about 734.2 ha (96.5%) of study area is marginally suitable.These results could be used as baseline information needed for mapping specific soil resource constraints for sustainable production of these crops in the study area.
Quantification of precipitation deficits on different time scales in Sierra Leone using standard precipitation index
(Springer Science+Business Media, 2022-12-19) Amara, Denis Magnus Ken
Rainfall erosivity estimation for Sierra Leone using non-parametric indices
(Springer Science+Business Media, 2019-08-14) Amara, Denis Magnus Ken
Soil Fertility Management in Sugarcane
(IntechOpen, 2025-10-09) Amara, Denis Magnus Ken
Sugarcane commonly known as “Saccharum officinarum L” is a major cash crop that holds significant importance in global sugar production. It contains roughly 84% pure juice and 16% dietary fiber and offers both sweetness and digestive benefits, promoting regular bowel movements. Sugarcane is a nutrient-intensive crop, and its continuous cultivation depletes soil nutrients. This makes it essential for nutrient restoration through proper soil management practices. Effective soil fertility management is therefore pivotal in achieving optimal yield, quality, and sustainability in sugarcane crop production. This ensures that sugarcane plants access essential nutrients throughout their growth cycle for maximum yield. Nutrients such as nitrogen, phosphorus, potassium, and various micronutrients are necessary for plant metabolism, photosynthesis, root development, and sugar accumulation. Adequate nutrient availability also contributes to better tillering, higher number of millable canes (NMC), and increased biomass production, all of which positively impact cane productivity. Deficiency of essential nutrients can hinder the growth and development of sugarcane, as well as impact various physiological processes. Hence, balancing nutrient availability and maintaining soil fertility is crucial for sustainable sugarcane production. Healthy soil enhances plant vigor and overall health and makes the crop more resistant to diseases and pests. Therefore, regular soil testing is a valuable tool for identifying nutrient status, deficiencies, and developing appropriate nutrient management strategies. Soil testing and analysis can help in determining the specific nutrient needs of the soil, allowing for more targeted and efficient fertilization. This chapter therefore discusses the key issues pertaining to the management of soil health and fertility for sustainable sugarcane production.
Soil quality under different land uses in hot semiarid agro-ecological region of India
(Hind Agri-Horticultural Society, 2014-12-15) Amara, Denis Magnus Ken
A study was undertaken to identify important soil quality indicators and develop soil quality index for different land uses in Singhanhalli-Bogur micro watershed of northern transition zone of Karnataka. Soil samples were collected and analyzed following standard analytical procedures. Principal component analysis (PCA) was used to select a minimum data set that best represent soil functions of the study area. Five soil quality indicators, namely clay, silt, porosity, exchangeable Mg and organic carbon were identified as the best soil attributes that represent soil functions. A high degree of correlation was observed between the soil attributes. The soil quality varied from low to high. A major portion of the study area was under medium and high soil quality but larger portion was under medium soil quality. Soil quality under forest was higher than open scrub, plantation and agriculture. The application of organic and inorganic fertilizers as well as appropriate land uses such as forestry was recommended in order to improve the soil quality of the study area.
Studies on Land Resource Inventory for Agricultural Land Use Planning in Northern Transition Zone of India through Remote Sensing and GIS Techniques
(Scientific Research Publishing, 2021) Amara, Denis Magnus Ken
Land suitability analysis is a prerequisite to achieving optimum utilization of available land resources. Hence, a study on land resource inventory for agricultural land use planning was conducted in the Northern Transition Zone of India to determine land capability and develop a suitability map for wheat and sorghum-based on physical and climatic factors of production using remote sensing and GIS techniques. Detailed soil survey information was used for this exercise. Four series (Singhanhalli, Mugli, Bogur and Venkatapur series) were identified and mapped into seventeen mapping units. Land capability classification showed that a greater portion of the study area belonged to class III followed by class IV with limitations of erosion, wetness and varying soil properties. Four land capability classes viz., II, III, IV, and VI, and seven subclasses viz., IIsf, IIItsf, IVs, IVt, IVts, IVtsf and VIt were identified. Major limitations of these subclasses were slope, erosion, depth, texture, coarse fragments, pH, organic carbon and base saturation. Soil suitability assessment revealed that the soils are moderately suitable to permanently not suitable. About 234 ha (31.6%) is moderately suitable, 494 ha (65.0%) marginally suitable and 10.2 ha (1.3%) permanently not suitable for wheat; while 78.5 ha (10.3%) is moderately suitable, 633.4 ha (82.3%) marginally suitable and 32.6 ha (4.3%) permanently not suitable for sorghum respectively. The moderate, marginal and permanent non-suitability was due to moderate, severe and very severe limitations respectively. However, it is possible to achieve potential yield of the crops in the study area if these limitations are addressed.
Studies on the Genesis of Soils in Jong River Basin in the Northern Province of Sierra Leone
(Scientific Research Publishing, 2022) Amara, Denis Magnus Ken
The soil resources of Sierra Leone remain an integral part of sustainable agricultural development but knowledge of the suitability of soils and their management requirements for a variety of land uses is still lacking to a greater extent. In this view, a detailed soil survey of three chiefdoms in Northern Sierra Leone was undertaken to evaluate the genesis of soils and interpret soil-landscape properties and their relationships using the toposequence and free style approach of soil survey. Three major soil types, viz, gravelly, gravel-free over gravel and gravel-free soils, formed either directly or indirectly from weathered and disintegrated parent materials of two geologic origins namely Rokel River Series (comprising of sandstone, shale and mudstone), and Granite and Acid Gneiss were identified. The gravelly soils are formed from sandstone and sandy shales of the Rokel River Series, which upon weathering released iron and hydrated oxides that hardened into plinthite upon drying. The gravel-free over gravel soils are formed from acid gneiss containing acid and intermediate igneous and metamorphic rocks, which upon weathering produced sandy clay textured soils whereas the gravel-free soils are derived from sedimentary rocks (shales and mudstones) of Rokel River Series, which upon weathering and action of organisms produced sandy clay loam and sandy clay textured soils. The gravel-free over gravel soils are mostly located in the summit and back slopes and show dark brown to dark yellowish-brown hue and moderate chroma, weak to moderate structure and absence of coarse fragments in the 0 - 40 cm layer, and a strong brown hue and high chroma, very weak fine angular blocky structure having abundance of coarse fragments from 40 cm and above. In these soils, the compactness of ironstone and sandstone gravels increases with depth. The gravel-free soils are found on three landscape positions, viz, back slopes, foot slopes and toe slopes. On the back and foot slopes, the soils are characterized by very dark brown to dark yellowish-brown hue and high chroma, sandy loam to sandy clay texture, coarse angular to moderate sub-angular blocky structure and absence of coarse fragments throughout the horizon. In these soils, the clay content and sand grain sizes were observed to increase with depth. On the toe slopes, the soils show black to greyish-brown hue and low chroma, silty loam to sandy loam, structureless and high water holding capacity.