Coffee – with or without?

You only had to look at the coffee under shade to see it was in better condition.

A major research programme: Connecting, enhancing and sustaining environmental services and market values of coffee agroforestry in Central America, East Africa and India (CAFNET), came to an end in 2011. Research in Rwanda has provided vivid proof of the virtues of growing trees on smallholder coffee gardens. This was just one of many CAFNET projects.

"During the 1960s and 1970s, coffee growing experienced its own green revolution," explains Fabrice Pinard, a coffee scientist seconded to the World Agroforestry Centre by the Centre de Coopération Internationale en Recherche Agronomique pour le Développement in France. Many growers and companies abandoned traditional methods of growing coffee under shade and began to plant coffee in rows under full sun. These intensive systems of production required the use of large quantities of fertilizers, pesticides and water, and they worked well in Brazil, Colombia and various other parts of the tropics.

Little wonder, then, that many governments encouraged smallholders to adopt similar systems. However, the results have often been pitiful. "Many smallholders can't afford to buy fertilizers or irrigate their coffee, and they're getting a fifth or less of the yield that they would be getting if they could afford the inputs needed to sustain full sun coffee," says Pinard.

The plight of these farmers encouraged CAFNET to examine the influence of shade on coffee production. The project focused on 50 smallholdings in Kivu, Rwanda. At each, the researchers studied the performance of four randomly chosen coffee bushes under shade and four growing in full sun.

Under shade, the mean harvest of coffee cherries over the 3-year research period was 9.6 kg per bush, compared to 7.1 kg in full sun. The production of green coffee was also higher under shade. "You only had to look at the coffee under shade to see it was in better condition," says Pinard. "The leaves were greener and more plentiful." He believes this is because cultivated coffee, whose ancestors come from the forests of Ethiopia and the Congo Basin, is adapted to shade conditions. It only performs well in full sunlight when it has a plentiful supply of fertilizer and water.

But why hadn't farmers planted more trees if it was so obvious that shade was beneficial? The answer is partly political. When the governments in Rwanda and Kenya first began to promote intensive systems of production, farmers were forbidden from planting trees in their coffee gardens. Fortunately, the extension services now recognize the virtues of providing shade and they are promoting tree-planting.

"Our research provides clear evidence to support this policy," says Pinard. It also provides guidance about which species of tree work best. Leguminous trees, such as Acacia and Albizia species, help to improve soil fertility, while avocado (Persea americana) and a local fig, Ficus thonningii, seem to stimulate coffee production.