Evaluation of surface nutrient balances and economic performance of the banana enterprise at Kabanyolo

Abstract

Banana is a crop grown globally and it is of major economic importance, and is the fourth most important food crop after rice, wheat and maize. The productivity of the East African highland banana has been declining despite the efforts being done particularly in areas with low soil fertility. Despite the low yields and soil fertility problems, fertilizer use is low since farmers are poor and cannot afford the high input costs. Sustainability of the system depends on the balance between the nutrient inputs used and offtake of nutrients from the harvests. A study was conducted to evaluate the surface nutrient balances and economic performance of banana enterprise at Kabanyolo. The study was conducted on the old banana plantations covering 4.2 hectares for the year 2022. The nutrient balances were determined using the partial nutrient balance approach since it is fairly simple and cost effective. The data sources included literature and farm records. The results collected were recorded and nutrient balances and gross margins computed. The results showed that the organic materials used included maize stovers, poultry manure, and soybean straw. These materials were got from the farm itself after previous harvests. The nutrient concentrations of the organic materials were determined and the amount of nutrients supplied calculated. N (345.97kg/ha/yr) was the most applied nutrient, followed by K (258kg/ha/yr), and lastly P (87.46kg/ha/yr). The nutrient concentrations in the harvested parts were determined, and the amounts of nutrients extracted through harvest calculated. K (112.1kg/ha/yr) was the most extracted nutrient through harvest, followed by N (27.3kg/ha/yr) and lastly P (4.3kg/ha/yr). K was extracted most because of its role in fruit maturity and improving bunch and finger size. The surface nutrient balances were calculated and N had the highest balance of (318.6kg/ha/yr), followed by K (146.1kg/ha/yr) and lastly P (83.2kg/ha/yr). The nutrient use efficiencies were highest for K (0.43) than N (0.08) and P (0.05). The gross margin of the banana enterprise was a positive gross margin of shs.3,085,108 per hectare, hence because of use of the cheap organic materials used at the farm. The positive balances and low use efficiencies indicate surplus of nutrients in the system which could be an environmental threat. Overall productivity of the enterprise is only about one third of productivity reports on- farm and these should be addressed to improve use efficiency of surplus nutrients.