Impact of poultry manure and groundnut shell on soil fertility, growth and tomato yield (Solanum lycopersicum l.) in the Gambia’s west coast region, the Gambia

The study explored the use of groundnut shells to improve soil fertility and enhance tomato growth and yield in an Inceptisol at the National Agricultural Research Institute. Four treatments were tested using a Randomized Complete Block Design (RCBD) with three replications: groundnut shells at 5 tonnes per hectare, poultry droppings at 5 t ha-1, a mixture of both at 2.5 t ha-1 each, and a control group. Results showed that organic manure effectively boosts soil fertility, serving as a viable alternative to inorganic fertilizers in central Gambia. Groundnut shells provided higher levels of potassium, calcium, magnesium, and organic carbon. The combination of poultry droppings and groundnut shells led to significant improvements in plant height, diameter, leaf area, and fruit yield compared to the control group. Additionally, soil pH increased from 5.4 to 6.5, and nitrogen levels rose from 0.34 gkg-1 to 0.77 g/kg with the combined treatment, achieving a 44% increase. Overall,the study recommends using groundnut shells and poultry droppings to optimize tomato.