Nutritional summary for bananas
Bananas have a very high nutrient demand – more so than most other crops.
With plantations yielding up to 100t/ha, nutrient removal is also very high. However, because 60% of the crop’s roots are in the top 15cm of soil, and the fact that nutrient leaching and volatilization are also major problems, careful fertilizer use, recycling leaf litter and compost is critical. Early removal of suckers will minimize nutrient cycling from the mother plant.
Common practice is to use frequent applications of fertilizer – particularly of nitrogen and potassium - throughout the season to maintain optimum growth. The early stage of vegetative growth is particularly important for bunch development. At this time, high levels of nutrients are needed to ensure establishment of the plant crop and also the setting of ratoon suckers. The plant crop in particular, requires higher levels of nutrients than that normally utilized by ratoon crops. The ratoon banana crop benefits from nutrient recycling from the mother plant and leaf litter, and hence fertilizer rates can be reduced.
Macronutrients
Uptake of potassium can be more than the total of all other nutrients combined and between 3-4 times higher than the amount of nitrogen needed. Peak demand is around flowering. Research shows that the majority of the crop’s total potassium needs should be applied before peak flowering. Both plant and ratoon crops utilize similar amounts of potassium during the season, with removal of around 5-7kg/t of fruit.
| Macronutrient Removal (kg/t of Fruit) | ||||||
| Cameroon | ||||||
| Type | N | P | K | Ca | Mg | S |
| Banana (average of 2 crops) | 1.97 | 0.25 | 6.60 | 0.21 | 0.32 | 0.27 |
| Plantain (average of 4 crops) | 1.6 | 0.23 | 5.04 | 0.15 | 0.21 | 0.14 |
| Ref: Marchal and Mallessard - 1979 | ||||||
Nitrogen is needed throughout the season to fuel growth, but the main period of uptake is during leaf and pseudostem growth. Plant crops have a slightly greater need for nitrogen earlier in the season than ratoon crops. Around 6kg of nitrogen is utilized for every tonne of whole plant material produced. Because the banana plant cannot store nitrogen, regular fertilizer applications are important to avoid deficiencies, particularly under conditions of high leaching.
Calcium is the third most important nutrient for the crop with around 3kg/t of plant and fruit utilized per season. Main uptake is before shooting or the shot stage of growth .
Phosphorous needs are small, generally less than 1kg/t of plant and fruit in Cavendish bananas. The crop requires a constant supply throughout the growth period.
Magnesium uptake is relatively even throughout the growth period. While between 30 – 40% of total nitrogen, phosphorus and potassium uptake ends up in the bunch, only 10-15% of the total calcium and magnesium finds its way into the fruit. However, calcium and magnesium are particularly important for good fruit integrity and long-term storage as well as overall banana yield.
The most rapid uptake of sulfur occurs from the sucker to shooting stage and the plant utilizes around 1kg/t of plant and fruit.
Micronutrients
While much lower amounts of micronutrients are needed to satisfy good growth, iron, zinc, manganese, boron, copper and molybdenum are key elements.
Iron is needed in largest quantities and, alongside manganese it is important to fuel growth.
Boron and zinc have a role to play in improving crop quality. Uptake of micronutrients is greatest during the early stages of growth.
