French: Banane; Spanish: Plátano, Banano; Italian: Banana; German: Banane
Permanent crop with a succession of herbaceous
generations by vegetative sprouting. Mostly triploid.
- for the Cavendish group of sweet bananas
(which account for nearly all international trade), 1 400 - 3 500/ha,
according to sunshine, cultivar, cropping technique and marketing
constraints such as the premium paid for larger-sized individual fruits.
With intensive mechanization and/or very high plant densities, in widely
spaced single or double rows closely planted within the row; otherwise
evenly spaced square or rectangular planting.
Flowering (plant crop):
- Cavendish group, 5-10 months after planting,
depending on planting material, climate, irrigation, cultivar and
Time from flowering to harvest: 80-180 days for
both plant and ratoon crops, depending mainly on climate ("heat
Figures for other varieties are less well established but differ little from the above.
Total uptake in normal conditions is, on the basis of available information:
Variations are due to the harvest index (much higher for the Cavendish group than for many other varieties), nutrient status (except nitrogen, the nutrient content of fruit is less affected than that of other plant parts by deficiency or excess) and the de-suckering technique. The figures given are for total net uptake at the harvesting stage: they do not include amounts lost in pruning/de-suckering, or wilting of older leaves, or through leaching by rainfall. Note that roots may account for 5-10 % of the total uptake, and corm 10-12 % (5 % in the case of CaO).
K absorption is largest during bunch growth (hidden and visible); N and P continous uptake from planting (or sucker start) to bunch emergence.
Plant analysis data
The International Reference Sampling (IRS) method, which was agreed at a conference held in the Canary Islands in 1975, requires leaf samples to comprise inner (i.e. closest to the midrib) exact halves of strips taken from both sides of the lamina and at its exact mid-length, from the third youngest fully expanded leaf either at full bunch emission (all female hands and no more than three male hands being visible) or at approximate floral initiation. Because the choice of sample is highly critical, published data and the basis of other sampling methods or where the sampling method is not clearly stated should be treated with great caution and tested against IRS data by the user to obtain conversion tables.
Unfortunately, not enough experience has been accumulated with the IRS method to be able to assess definitely all its standards. The table below includes, in italics, some non-IRS data where sufficient information was available for conversion to be practicable, and, in parenthesis, values expressed as mere orders of magnitude where such conversion was not possible.
Whilst N and K should be supplied according to the very high biomass requirements of the crop, attention must be given to maintaining an appropriate soil cationic balance. On most soil types this means (with pH around 6.0) about 80 % CEC saturation by K, Mg and Ca in the approximate proportions 1:3:6. Dressings of dolomite and/or limestone, for incorporation into the soil, should be calculated so as to achieve and maintain these proportions in the top 20 cm of soil. On highly unsaturated soils with a high cation exchange capacity, this may seldom be possible, in which case attention should be given principally to the K:Mg ratio, which should never exceed 1:2 in ferrallitic or sandy soils or 1:1 in volcanic or organic soils. The level of exchangeable K should preferably be raised to about 10 % of the total exchangeable cations by a basal application in the first year and subsequently maintained by dressings calculated to compensate for removals and leaching losses.
The amounts of N and K2O to be given to a plant crop should be calculated from the expected yield on a particular field and the total uptake per metric ton of whole bunches as quoted earlier. N application should be split into a number of dressings so as to provide a continuous supply from planting right through to harvest, with smaller and more frequent dressings where the risk of loss by leaching is higher (Godefroy et al, 1989), ranging from intervals of 1-3 months in relatively dry climates down to every 2-4 weeks in the humid tropics with suitable modification in seasons of high growth potential or in seasons affected by cold or drought. Subject to the demands of maintaining a correct cationic balance, the K application is generally divided in a rather similar manner to that of N except that dressings should be smaller at the beginning of the growth period and increased during the months immediately before and after flowering.
Similar calculations may be made for ratoon crops, making due allowance for the large losses resulting from chopping down the mother plants, and the more rapid growth during a shorter time period. In practice, the same average monthly rates as for the plant crop are generally adopted.
Preferred nutrient forms
Given adequate S, the cheapest forms of N and K fertilizers available may be used. Potassium nitrate, although acceptable in theory, is scarcely ever used except in irrigation water, due to its high cost and liability to loss by leaching. Where there is a need for added S, this can be given either in the form of a sulphate-based N fertilizer or, preferably on acid soils, potassium sulphate, so that S would account for 3-5 % of the total input unless abundant organic manure is used. Double K-Mg sulphates (Patentkali, etc) are useful where Mg deficiency is incipient. The preferred form of P depends on soil pH and P-fixation capacity. Where appropriate, rock phosphates can contribute, with lime and/or dolomite, towards CEC saturation; and low-P compound fertilizers are convenient except on soils where P-fixation capacity is high.
Present fertilizer practices
Departures from recommended usage often result in low yields, through under-use, or in poor quality and uneconomic production due to imbalanced or over-use or incorrect timing.
Organic manures are excellent for improving soil conditions and provide variable amounts of macronutrients, which must be taken into account if imbalances are to be avoided; they may also supply all the micronutrients needed. Cattle or chicken manures, at rates of 35-120 t/ha, are widely used in some countries, and in others, residues such as coffee pulp, cacao shells and composted town refuse, while copious mulching with grasses or branches has been common practice for decades in many regions. Where high yields are obtained by using only mineral fertilizers, the soil organic matter content can be improved by returning around 200 t/ha/year of plant residues, but care must be taken to ensure that adequate amounts of all macro- and micronutrients are provided.
N fertilizer is used almost everywhere unless abundant organic manure is applied; but even with abundant manure application K fertilizer must also be given except on volcanic soils containing very high reserves. Mg is considered the third most important nutrient, whether incorporated in a soil amendment or broadcast as a straight fertilizer (Epsom salts or kieserite) or in mixed or compound fertilizers.
Most fertilizers are hand-spread except when basal dressings are incorporated during land preparation. However, there is considerable controversy over the best method of placement. With good control of nematodes and soil aeration, an even broadcast would appear more logical, but applications in practice are often concentrated within a circle of 1.0-1.5 m diameter around the pseudo-stem, or (after flowering) in a crescent shape around the daughter plants. In mechanized fields the fertilizers are often spread along the rows.
Foliar feeding is efficient with the right nutrients and wetting agents. It is preferably used successfully for micronutrients, especially when they can be mixed with the aerial oil-fungicide sprays regularly applied against Sigatoka disease in tropical climates. Rates of 5-10 kg/ha Zn, B or Mn (in descending order of importance) applied in this way once to three times a year are sufficient, instead of soil applications of 20 kg/ha or more which are often ineffective because of blocking antagonisms.
Some individual growers apply amounts up to 1 200 kg/ha N, 800 kg/ha P2O5, 1 800 kg/ha K2O yearly, but the most common practices for Cavendish cultivars in various countries are summarised in the following table. The higher figures correspond broadly with the highest yields. The less productive stands, whether of Cavendish or other cultivars, receive less fertilizer but are less profitable.
GODEFROY, J.; MARCHAL, J.; NAVILLE, R.: Fertilisation des cultures fruitières en Afrique intertropicale. Fruits 40 (5), 327-344 (1985)
LAHAV E.; TURNER, D.: Banana Nutrition. Internat. Potash Inst., Berne, Switzerland (1983)
MARTIN-PREVEL, P.: La nutrition minérale du bananier dans le monde. Fruits 35 (9), 503-518+,nd (10), 583-593 (1980)
MARTIN-PREVEL, P.: Banana. In MARTIN-PREVEL, P.; GAGNARD, J.; GAUTIER, P. (eds.), Plant Analysis as a Guide to the Nutrient Requirements of Temperate and Tropical Crops. Ed. Lavoisier, New York-Paris (1987)
SOTO, M.: Bananos. Univ. Costa Rica, San José (1985)
Author: P. Martin-Prevel, Institut de Recherches sur les Fruits et Agrumes (IRFA), Centre de Recherches CIRAD de Montpellier, Montpellier, France