Friday, 21 December 2012 00:00
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Banana can protect coffee from the effects of climate change

Growing coffee and banana together not only generates more income for small-holder farmers, compared to growing either crop alone, but it can also help coffee production to better cope with the effects of climate change, a recent study has shown.

The study, which sought to understand the potential impact of climate change on coffee-based livelihoods in the East African highlands, found that the areas suitable for growing Arabica coffee will drastically decrease in the future leading to losses in the region that may exceed US$100 million annually. This is not only a threat to the countries’ foreign revenue, but it also puts at risk the livelihoods of millions of small-holder farmers depending on the crop.

The researchers from the International Institute of Tropical Agriculture (IITA) in collaboration with those from the Colombian-based International Center for Tropical Agriculture (CIAT), used climate models and climate analogues to predict the impact of climate change on coffee production.

The researchers walked down the slopes of Rwenzori Mountains, in Uganda, where the lower one goes, the temperatures get progressively warmer and drought stress becomes a more serious problem—similar to walking into a “future climate”.

The approach illustrated that areas below 1,300m may well become completely unsuitable for Arabica coffee production. In areas between 1300-1700m, coffee will be severely affected if current farming practices that use traditional varieties and make limited use of water conservation and shade technologies remain unchanged.

In Uganda, coffee is the most important export crop generating approximately 20 per cent of the foreign exchange earnings. One-third of the coffee export value is from Arabica coffee, which requires a particularly cool tropical climate that is only found at higher altitudes, generally above 1400m. Arabica is therefore very sensitive to a rise in temperature induced by climate change. Coffee is also among the top three commodity exports in Ethiopia, Rwanda, Burundi, and Tanzania.

Shade provided by shade trees or banana can help coffee to cope with the warmer climate and with drought shocks. Research has shown that shade can reduce the temperature in the understory plants by up to 2º C or more.

Past research by IITA also showed that growing coffee and banana together increased the farmers’ income – the coffee yield remained the same despite creating room for the banana and the farmer gained additional income from selling the banana. This study strengthens the case for growing coffee and banana together as it provides both short- and long- term benefits to farmers.

“Strategies to help farmers cope with climate change will often be more successful if farmers are also able to see the immediate benefit of their investment.

By growing banana and coffee, in a year’s time, the farmers will be earning extra money from selling banana,” says Dr Piet van Asten, an agronomist with IITA based in Uganda and one of the researchers. “And if coffee fails, then bananas will still provide the farmer with food and income. It is a perfect win-win situation for both crops and the farmers.”

The researchers also interviewed farmers in the region who said the climate was already changing—the droughts were becoming longer, rainfall was becoming more erratic, and the rainy seasons were becoming shorter. This negatively affected the flowering of coffee and reduced the sizes of the berries.

The farmers had also observed that pests and diseases such as leaf miners, coffee berry borers, mealy bugs, and leaf rust were on the rise. However, the study found that leaf rust incidences were 50 per cent lower in coffee that was shaded by banana compared to the unshaded plants.

The findings are supported by another study by Alessandro Craparo from the University of Witwatersrand with support from IITA, CIAT, and CGIAR Consortium Program on Climate Change and Agricultural Food Security (CCAFS) and the Tanzania Coffee Research Institute (TaCRI) that is looking at the influence and impact of climate change variability on Arabica coffee in the Mt Kilimanjaro area. It found that every minimum temperature increase of 1º C would lead to a yield loss of almost 100 kg/ha, representing 20 per cent of the current yield.

The only drawback to adding shade to coffee is that it demands more nutrients and farmers will have to invest in maintaining the soil fertility.

“The downside of adding shade or shade crops to a coffee system is that it increases competition among the different plants for water, nutrients, and light. This competition needs to be managed by using good agronomic practices such as integrating fertilizers and organic nutrient inputs, appropriate plant density and canopy management, and good soil and water conservation practices to adapt successfully to climate change,” Dr Van Asten said.

The studies on impact of climate change on coffee systems in Uganda received support from Climate Change, Agriculture and Food Security (CCAFS), the Consortium for Improving Agriculture-based Livelihoods in Central Africa (CIALCA) project, Oxfam, USAID, Wageningen University (WUR), and a wide range of coffee sector partners in the region.


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