Effects of organic fertilizers and irrigation regimes on soil moisture content and beetroot (Beta vulgaris L.) performance in Northern Ghana

Abstract:

Beetroot (Beta vulgaris L.) is a highly nutritious and economically valuable crop globally; however, its optimal production in tropical and semi-arid regions is increasingly threatened by declining soil fertility, erratic rainfall, and rapid soil moisture depletion. These constraints are particularly severe in the semi-arid ecological zone of Northern Ghana, where high evapotranspiration rates and poor soil moisture retention significantly limit crop development and yield. To address these challenges, this study evaluated the effects of different organic fertilizers and irrigation regimes on soil moisture content, growth, and yield performance of beetroot. A pot experiment was conducted at the University for Development Studies in Ghana, during both wet and dry seasons using a factorial design. Treatments included three organic amendments (Cow Dung, Sheep Droppings, and Compost) and a control, combined with three irrigation regimes (100%, 75%, and 50% Crop Water Requirement [CWR]). Growth parameters (plant height, number of leaves, leaf area, Leaf area index and chlorophyll content) and crop yield parameters (root length, bulb weight, dry bulb weight, bulb diameter, and water use efficiency) were monitored.

Analysis of Variance (ANOVA) revealed that the efficacy of the treatments varied significantly by season. During the wet season, the application of organic fertilizers showed no significant difference (p>0.05) on most growth and yield parameters. Conversely, in the dry season, organic amendments had a significant effect on fresh bulb weight (p<0.05) and total yield (p<0.05), with compost producing the highest vegetative growth and yield. Result also indicated that soils amended with sheep droppings consistently recorded the highest soil moisture content across all irrigation levels, demonstrating superior moisture retention capacity. Furthermore, ANOVA demonstrated that irrigation regimes significantly impacted the final yield (p<0.05) and Water Use Efficiency (p<0.05). The 100% CWR regime produced the maximum fresh bulb yield of 4.45 t/ha, whereas deficit irrigation significantly constrained production, reducing yields to 2.80 t/ha at 75% CWR and 2.46 t/ha at 50% CWR. A significant interactive effect between organic amendments and irrigation regimes (p<0.05) was recorded for bulb weight, with the combination of compost and 100% CWR resulting in the highest overall yield (8.06 t/ha). The study concludes that while sheep droppings are most effective for soil moisture conservation, the application of compost under full irrigation (100% CWR) is the optimal strategy for maximizing beetroot productivity in Northern Ghana. This approach can help farmers increase production, use water effectively and maintain soil health in drought-prone regions, paving the way for more resilient agricultural systems.