Agriculture and Environment: Bananas

Better Management Practices: Use of Agrochemical Inputs

In some areas, the application of agrochemicals is becoming more targeted and use per hectare is declining.

Closer monitoring of nutrient imbalances, infestation rates, and the movement of disease vectors is a key technique used to determine the type of chemical to use as well as the best time for application.

Farms in Costa Rica using this technique have reduced their pesticide spraying, for example, from 47 to as low as 35 times per year (Panfilo Tabora, personal communication).

Increasing the efficiency of fertiliser use
Many chemicals applied to banana plantations are lost rapidly due to leaching. Smaller, more targeted to applications spread out over the course of the year, for example, increase the efficiency of fertiliser use. However, the overall efficiency is still lower than it needs to be if the fertilisers are applied by themselves.

Use organic matter in applications
One of the best ways to increase the efficiency of fertiliser use is to incorporate applications in organic material (either what is already on the field or mixed with compost) so that they bind and are released more gradually. This reduces leaching and makes the nutrients available in a slow release form over a longer period of time.

Planting cover crops
Cover crops planted below the bananas are an efficient way of accomplishing this goal. Not only do they provide organic matter, but some species also fix nitrogen that would otherwise have to be added to the soil. Different cover crops work better in banana plantations located in different parts of the world.

Enrichment planting with legumes
Another strategy is to invest in a more intense, enriched fallowing of degraded areas or areas that are at the end of the current production cycle. Enrichment planting with legumes for 3-5 years can rebuild the soil and decrease nematode problems.

During the fallow, the cover crops are enriched with the nutrients that their deep roots bring up to the plants. The leaves become rich in potassium and phosphorous, which have been leached down in the soil over the years. The roots become rich in nitrogen, as a result of the nitrogen-fixing bacteria that live in root nodules on legumes. Fallowing also builds up organic matter in the form of litter on the surface, which acts as mulch and eventually increases soil organic matter as it decomposes and is incorporated back into the soil (Panfilo Tabora, personal communication).

Reducing foliar spray applications
There are also other techniques to deter the growth of specific diseases, including the use of resistant varieties as described in the previous section. In a 3 year experiment on the commercial operation of an independent banana grower in Costa Rica, sprayings of beneficial microorganisms have increased yields, reduced foliar chemical spray frequency by 15%, and eliminated 75% of the nematicide applications.

The microorganisms included lixiviates derived from compost and bokashi (fermented banana waste, described later in the section on reducing wastes) (Panfilo Tabora, personal communication). There are indications that this approach can be improved further. Experiments at EARTH's commercial banana farm have reduced foliar spray applications of pesticides by 30%.

Experiences at EARTH's commercial banana farm
This overall approach has now become standard practice on plantations. EARTH researchers found that when beneficial microorganisms were incorporated into the spraying applications, the number of healthy leaves increased. Such applications have been followed by a marked drop in pest infestation (Panfilo Tabora, personal communication).

However, with increased areas coming under cultivation, the total use of chemicals and the cumulative impacts are increasing even though per-hectare applications may be declining in some regions, so more work needs to be done in this area.

At EARTH University's packing house, there is a very deliberate separation of the fungal sprays to treat the banana cluster base (crown) from the rest of the water treatments used in processing. The fungal spray drips are collected and diverted to a dedicated settling pond where the chemicals degrade; the settling pond is covered so the chemicals cannot be further diluted.

Working towards elimination of fungal sprays
EARTH University has also begun to experiment with a naturally derived fungicidal compound that would allow for the elimination of fungal sprays altogether. The natural compound is based on citrus seed extracts and has been used for some two years. By all counts, both at the production end and with the buyers, it has performed well. Natural chemicals have increasingly become the norm (Panfilo Tabora, personal communication). Through these and other strategies, EARTH University in Costa Rica has been able to reduce pesticide use by more than half.

Reducing the use of metals
In Costa Rica it has also been observed that after some twenty to thirty years of continuous spraying of manganese (from the fungicide mancozeb), zinc, iron, and copper, these metals have accumulated to levels that are considered toxic to banana roots.

This tends to stress or debilitate the roots and make them more susceptible to nematodes. Experiments at EARTH University's commercial farm suggest that applying organic matter to the soil can halve levels of these metals, and result in healthy and numerous roots (Panfilo Tabora, personal communication).

A recent comparison of the chemicals used by the Chiquita company's Better Banana-certified farms in Costa Rica to a progressive but uncertified competitor suggest that the certification program is having positive impacts on the use of nearly all pesticides. The study found that up to 2002, there was an overall trend to reduce the use of all chemicals with the exception of post harvest fungicides, which showed an increase.