School of Agriculture, Environment, Water and Natural Resources Management (JA)

Influence of sulfur, calcium and magnesium supplementation on the post-harvest and storage quality of onions for increased production and marketability in Kenya

Wed, 01 Jul 2026 00:00:00 GMT

Influence of sulfur, calcium and magnesium supplementation on the post-harvest and storage quality of onions for increased production and marketability in Kenya Akuja, Thomas E.; Kirambia, Rosemary K.; Xavier, Briggx Nchogu Onion (Allium cepa) is a vital crop in Kenya, both in the diet due to its nutritional health benefits as well as its economic gains. However, the potential of onions as a functional food is limited due to suboptimal agronomic practices, poor soil nutrient management, and high post-harvest losses, which affect marketability. Therefore, this research aimed to investigate the effects of sulfur, calcium, and magnesium supplementation on the growth, yield, and bulb development of onions to increase production and marketability. The research adopted RCBD in two sites in Kenya: Kisaju-Kajiado County and Koma-Machakos County. Experimental treatments included varying levels of sulfur, calcium, and magnesium supplementation and their combinations at different levels in onions and their effects were evaluated towards the pests and diseases, onion bulb firmness and prices/kg. Normality, regression, and chisquare preliminary tests were performed on the data using SPSS software and the data were found to be parametric. ANOVA tests were then performed, and where significant differences were found, post-hoc tests were performed. All onion varieties at all treatments in site 1 reported few incidences of onion chafer grub pest attacks and rot disease, with 0 reported cases across most plots. "Texas Grano” yellow onion variety bulbs were more stable at S, Ca&Mg application at 60kg/ha with 0.39g weight loss after two weeks of curing. “Texas Grano” yellow onion at S, Ca&Mg@40kgs/ha reported the highest gross market prices of KES 180/kg with 15 onions due to reduced pest and disease incidences, as well as firm bulbs. Correlation analysis was also performed, and a weak relationship of 13.7% was found between bulb firmness and the gross market prices/kg. Therefore, based on the results, this research study concluded that the use of sulfur, calcium, and magnesium supplements significantly increases onion growth, yield, and bulb development, and significantly increases onion production and marketability. The study contributes to improving onion production and yield, as well as the crop's economic value, to address food security. The findings are therefore beneficial to onion farmers, policymakers, and other key stakeholders in the field of agriculture. DOI No.: 10.24940/theijst/2026/v14/i7/ST2607-001

Effect of varying rates and combinations of sulfur, calcium and magnesium supplementation on the growth, yield and bulb development of onions for increased production and marketability in Kenya

Wed, 01 Jul 2026 00:00:00 GMT

Effect of varying rates and combinations of sulfur, calcium and magnesium supplementation on the growth, yield and bulb development of onions for increased production and marketability in Kenya Akuja, Thomas E.; Kirambia, Rosemary K.; Xavier, Briggx Nchogu Onion (Allium cepa) is a vital crop in Kenya, both in the diet due to its nutritional health benefits as well as its economic gains. However, the potential of onions as a functional food is limited due to suboptimal agronomic practices and poor soil nutrient management, which affect its production and marketability. Therefore, this research aimed to investigate the effects of sulfur, calcium, and magnesium supplementation on the growth, yield, and bulb development of onions to increase production and marketability. The research adopted RCBD in two sites in Kenya: Kisaju-Kajiado County and Koma-Machakos County. Experimental treatments included varying levels of sulfur, calcium, and magnesium supplementation and their combinations at different levels in onions and their effects were evaluated towards the bulb weight/scallion biomass, bulb diameter and onion profitability. Normality, regression, and chi-square preliminary tests were performed on the data using SPSS software and the data were found to be parametric. ANOVA tests were then performed, and where significant differences were found, post-hoc tests were performed. Onions subjected to treatment of S, Ca&Mg@40kgs/ha reported the highest gross market prices, at KES 180/kg, due to the high bulb weight and scallion biomass, measured as an average of 15 onions on the "Texas Grano" variety. Ca&Mg@30kg/ha had the highest bulb diameter with 42.6mm. The Kisaju-Kajiado site had the highest general performance and profitability, with net returns of KES 76.94/kg on average, with the "Red Creole" variety having the highest at S, Ca&Mg@40kg/ha, with net returns of up to KES 77.44/kg on average. Correlation analysis was also performed, and a strong relationship of 95% was found between bulb weight and scallion measure and the market prices/kg. Therefore, based on the results, this research study concluded that the use of sulfur, calcium and magnesium supplements significantly boosts onion growth, yield and bulb development, increasing the production and marketability of onions in turn. The study contributes to improving onion production and yield, as well as the crop's economic value, to address food security. The findings are therefore beneficial to onion farmers, policymakers, and other key stakeholders in the field of agriculture. DOI No.: 10.24940/ijird/2026/v15/i7/JUL26007

Spatial and statistical analysis of groundwater chemical composition in Mui basin block C, Kitui County, Kenya: Relationships among ph, nitrates, and total dissolved solids

Mon, 22 Jun 2026 00:00:00 GMT

Spatial and statistical analysis of groundwater chemical composition in Mui basin block C, Kitui County, Kenya: Relationships among ph, nitrates, and total dissolved solids Kibos, Nurh K.; Ogondo, Julian A.; Kerandi, Noah M. Groundwater quality assessment is critical for sustainable water resource management in arid and semi-arid regions. This study investigated the spatial distribution and interrelationships among pH, nitrate concentrations, and total dissolved solids (TDS) in groundwater from Mui Basin Block C, Mwingi Central, Kitui County, Kenya. Water samples were collected from all existing 32 sampling points comprising boreholes, shallow wells, and earth dams, representing shallow (1 - 10 m), moderate (10 - 30 m), and deep (>30 m) aquifer systems. Physicochemical analysis was conducted following standard methods, and spatial distribution patterns were mapped using Inverse Distance Weighting (IDW) interpolation in ArcGIS. Statistical analyses, including descriptive statistics, one-way ANOVA, and Pearson correlation, were performed to examine relationships among parameters. Results revealed mean values of pH 7.84 ± 0.89, TDS 964.74 ± 893.76 mg/L, and nitrate 56.11 ± 44.52 mg/L. ANOVA indicated no significant variation in these parameters across different aquifer depths (p > 0.05), suggesting uniform hydrogeochemical processes throughout the basin. Strong positive correlations were observed between electrical conductivity and TDS (r = 0.99, p < 0.01), and moderate correlations between nitrate and salinity parameters. Spatial analysis revealed elevated TDS and nitrate concentrations in the central and southeastern portions of the basin, likely influenced by geological formations, agricultural activities, and limited recharge. The findings indicate that groundwater quality in Mui Basin Block C is primarily controlled by water-rock interactions and anthropogenic inputs rather than aquifer depth, with implications for targeted water quality management strategies in similar semi-arid environments. DOI: 10.4236/gep.2026.146005

Litho-structural mapping via machine learning and geodata on remotely sensed data in the Tharaka-Kanzungo, Kitui-Kenya

Fri, 31 Oct 2025 00:00:00 GMT

Litho-structural mapping via machine learning and geodata on remotely sensed data in the Tharaka-Kanzungo, Kitui-Kenya Odek, Jerald; Boitt, Mark; Thiong’o, Kuria; Kariuki, Patrick C. Litho-structural mapping is critical for resource exploration and hazard assessment, supporting economic development. This study applies Planetscope and ALOS Palser DEM data to conduct lithological and structural mapping in the Tharaka-Kanzungo region of Kenya's Northern Kitui County. The approach integrates support vector machine classification with manual (shaded relief) and automatic (PC Line module) lineament extraction. Planetscope’s high spatial resolution enabled effective rock unit discrimination, while ALOS Palser DEM data enhanced linear-structural analysis. SVM classification achieved 76.24% accuracy and a kappa of 70%, successfully identifying lithologies such as granitoid gneiss, semi-pelitic, calc-silicate, sillimanite-biotite, hornblendite, and crystalline limestone. Comparative results showed automatic methods detected more, shorter lineaments sensitive to texture and vegetation, whereas manual extraction captured fewer, longer, and distinct orientations. Stereographic projections further revealed tectonic features including shear foliations and lineations, aiding tectonic interpretation. The dominant NE-SW and NW-SE trends indicate structural influence on fluid pathways and potential mining zones. The integration of remote sensing techniques with ground-based validation produced a high-accuracy geological map, consistent with existing data. This approach demonstrates strong potential for updating maps and guiding mineral exploration in remote or inaccessible regions. DOI: 10.7176/JEES/15-5-02