Water trenches are dug mainly as a means to harvest water and channel it into the field to the plants. However, they can also help to control soil erosion. The larger the trench, the more water it will harvest.
A trench can be any length but should, ideally, be about 2 ft wide and at least 1 ft deep. Trenches must be dug across the gradient (or slope) of the field.
Field size and gradient will determine how many trenches are needed, and how far apart they should be. The bigger the field, the closer the trenches. Preferably, one trench should be dug after every two lines of plants (6m-8m apart).
Fields with a steep gradient will require more trenches to arrest water runoff. In some cases, grass may have to be planted on the upper side of the trenches to further reduce erosion. Any type of grass can be used, but vetiver grass is very good for this purpose. It is best to dig trenches either before the bananas are planted, it is best to dig trenches either before the bananas are planted, or as soon as possible afterwards.
If trenches are dug when the plants are established and growing, the roots will be damaged. Over time, as soil is washed into them, the trenches will ‘silt up’, so they will need to be reopened and maintained.
Forking the soil in the trenches, to break any hard crust that may have formed and loosen it, is also important and will ensure that the water can percolate into the field.
Mulching is the covering of soil with plant residues. It is another way to help retain moisture in a field. The deeper the mulch, the better the soil moisture retention will be. Blanket mulching with thick grass is recommended.
Benefits of mulching
- Ensures better water retention in the soil
- Reduces soil erosion
- Improves soil fertility in the long run.
- Mulch suppresses weeds
How to mulch
- Spread the mulch like a blanket, up to depth of about 30cm from base of the banana.
- Appropriate mulch should be between at least 8-15 cm thick.
- Place the mulch 1.5 - 2 ft from the mats to allow space for forking to loosen the soil and for effective weevil control. When mulch is close to the mat, roots tend to come up towards the surface and this weakens the plant making it susceptible to toppling.
- In a newly established field, apply mulch around the plant (spot mulching)
- Any other grass or weeds that grow up through the mulch must be hand weeded.
- Do not use a hoe for weeding, banana roots feed near the surface of the soil and will be damaged if a hoe is used.
- Remove weeds (such as couch grass, comelina, and cyperus) from mulch materials as these can multiply in the field and increase the weeds burden.
- Preferably apply dry crop residues
- Banana residues (self- mulch) e.g. leaves, chopped pseudo stems
- Other crop residues e.g. maize stover, rice straw, bean straw, napier grass
- When using external banana residues, avoid using materials affected by pests and diseases.
Weed control is important when maintaining a banana plantation. Weeds and other unwanted plants compete with the banana for water and nutrients, and so should be removed. Do not use a hoe to weed the field.
Banana roots stay close to the surface of the soil and spread laterally, forming a ‘mat’ across the planting area. Weeding with a hoe will damage the roots and weaken the plants which, in turn, will affect the yield.
Weeding must only be done by hand or, at a later stage, with herbicide. Once the weeds have been uprooted, they should be removed from the field and destroyed
Detrashing refers to the removal of unwanted, dead or dying leaves at regular intervals. Healthy banana plants produce one new leaf every two weeks. As the plant grows, some leaves will be dead, some will be dying, and some will be forming.
How to de-trash
- Starting from the outermost layer of leaf sheaths, trim any dead leaves with a sharp knife or curved knife.
- Be sure to only cut the dry leaves and sheaths to avoid contact with plant sap.
- Only the dead and dry leaves must be detrashed and arranged between banana plants as mulch.
- Never cut or detrash functional leaves, these are needed for photosynthesis.
Importance of de-trashing
- Detrashing regularly keeps the plantation healthy
- Prevents latent infections of banana bacterial wilts, black sigatoka which can be spread by transfer of sap from plant to plant by the tools if the leaves are not dead and dry.
- Improves penetration of sunlight
- Improves air circulation in the field
- Provides internal mulch
- Prevents harboring of banana weevils
- Makes the plantation look attractive
This is the removal of unwanted or excess suckers from banana plant to maintain the optimum plant population per mat. The number of suckers around each plant (mat) must be restricted so that competition for resources is limited. Keeping 2 - 4 suckers per mother plant is advisable, depending on the bunch and yield size you want or require.
This can either be as 1 mother plant and 2 daughter plants, or as 1 mother plant, 2 daughter plants, and 2 smaller daughter plants.
Use a de-suckering spear and not how to avoid injury to the mother plant and other suckers.
Water suckers should be removed and destroyed. Keep the strongest of the sword suckers; these can be used to produce future crops.
Staggered sucker selection - this is the selection of suckers in stages such that the farmer has a continuous harvest. While selecting suckers, the farmer should not only focus on choosing vigorous suckers but should also consider selection based on the suckers’ growth stages and direction in order to ensure continued production.
Importance of staggered sucker selection
- Allows the farmer to have a consistent harvest throughout the year.
- It reduces nutrient competition because nutrients are well utilized by the suckers that remain on the mat at that particular time.
- The higher the number of plants the higher the nutritional requirements.
Corm removal is the removal of the unwanted corm from the banana plant. This is important because it helps to destroy the breeding ground for weevils.
Appropriate corm removal procedure
In corm removal, a farmer needs to use clean tools (Pick axe & panga). Corm removal depends on extent of weevil damage in the field. If the field is clean, corms that are immediately adjoined to suckers are left to support the mat but they should be covered with soil. All other previous corms should be removed.
If the harvested corm is heavily damaged, cut off the damaged tissue and leave the clean part to support the mat.
Removed corms should be cut into small pieces to ensure quick drying and destruction of eggs and larvae of the weevils.
Male bud Removal
When they flower, at about 8 - 9 months, banana plants produce both male and female parts. However, the male part, or bud, is not needed and should be removed.
Why remove male bud?
- This is done to encourage all of the plant’s nutrients to go to the female part, which is developing into the fruit. Male buds also have natural openings through which Banana Bacterial Wilt could enter the plant, so removing them minimizes the risk of disease.
- Male buds are easy to recognize - they look like long tails with heads (see image below).
- Male bud removal could ensure a good bunch weight.
It is recommended to remove the male bud if sheaths of last cluster have dropped off. Use a forked stick and not sharp objects to prevent disease spread to avoid damaging the banana fingers. Fix the forked stick towards the middle of the male bud stalk and twist clockwise until it drops off.
Forking is the loosening the soil around the mat using a forked hoe. Forking the soil breaks any hard crust that may have formed and loosens it thus ensuring the water to percolate into the field.
Benefits of forking
- Improves infiltration of water into the soil
- Reduces run off and thus controls soil erosion
- Enables the plant to easily access externally applied nutrients e.g. from manure
Intercropping is the growing of more than one crop in the same field, especially in alternating rows. The goal of intercropping is to produce a greater yield on a given piece of land by making use of resources that would otherwise not be utilized by a single crop.
However, a farmer needs to understand the appropriate crops recommended for inter-cropping with banana, their impact on banana performance and possible diseases that may arise from intercropping.
How and when to intercrop
When bananas have just been planted is the time to consider whether or not you want to intercrop. When intercropping, it is important to fertilize and mulch the field to maximize the moisture and nutrient content of the soil. Intercropping is possible in a field that has already been mulched.
Some crops are more suitable for inter cropping with banana than others. Perennial crops, such as lemon should not be mixed with bananas. Never intercrop banana with root crops such as potatoes because digging the soil to plant and harvest them will cause damage to the banana or cereal crops like maize, rice etc.
- Where banana is the main crop, for every two lines of banana, plant one line of coffee (Robusta at 3mx3m and Arabica at 2.4m x 2.4m) or one coffee bush versus 4 banana mats, that is, coffee bushes shouldn’t exceed 500 per hectare (about 200 plants per acre).
- If coffee is the main crop, the banana mats should not exceed 750 mats per hectare (about 303 plants per acre).
- When intercropping with beans, farmers are encouraged to plant beans in rows to minimize competition. At flower shooting stage, deleaf bananas to not less than 7 leaves in order to reduce shading the beans. It is also important to incorporate crop residue from the beans as mulch.
- If you must plant other crops such as roots, tubers and other crops, plant at the edges of the banana field e.g. cassava, Irish potatoes, sweet potatoes, vegetables etc.