Partners

Institut de recherche agricole pour le développement (IRAD, Cameroon)
Montpellier Supagro (France)

This work was conducted within the Agroforesterie-Cameroun research platform in partnership.

For further information

Jagoret P., Michel-Dounias I., Snoeck D., Ngnogué H.T., Malézieux E., 2012. Afforestation of savannah with cocoa agroforestry systems: small-farmer innovation in central Cameroon. Agroforestry Systems, 86: 493-504. Doi: 10.1007/s10457-012-9513-9

Cultivating biodiversity to convert grasslands into productive cocoa plantations

06/2013

Cocoa growing is generally seen as one of the factors in the deforestation of humid tropical zones. However, in central Cameroon, on the contrary, it is helping with reforestation: in the region, many farmers set up their cocoa plantings on grasslands. To be able to do this, they have invented complex agroforestry systems in which food and fruit crops, forest trees, palms and cocoa trees are combined and succeed each other. Researchers from CIRAD and their partners in Cameroon have analysed the functioning of these cocoa plantings, which, with similar yields to plantings set up on forest land, are an example of successful ecological intensification.

In Africa, cocoa growing is associated with deforestation, since cocoa trees are generally planted on recently cleared forest land. In Cameroon, it has less of an impact, since farmers only partly clear the forest to plant their cocoa trees, which they then grow as part of complex agroforestry systems.

In the transitional forest-grassland zone in the centre of the country, farmers also plant cocoa on grasslands dominated by satintail grass (Imperata cylindrica ). How to they manage to convert these grasslands, which are apparently unsuitable for cocoa, into productive, sustainable cocoa plantings? What crop combinations and successions do they practice to achieve this?

To answer these questions, a team from CIRAD and IRAD studied farmer practices in the Bokito region, where almost half the cocoa plantings were set up in grassland areas.

Yields similar to those of gallery forest plantings

In the region, setting up cocoa plantings on grasslands is an old practice, dating back to the 1950s, which subsequently regressed with the development of cocoa growing in gallery forests. Since 1980, with forest land becoming increasingly scarce, cocoa plantings have more often been set up on grasslands than on forest land.

Although grasslands are not suitable for cocoa, farmers manage, after twenty years or so, to achieve raw cocoa yields similar to those of plantings set up in gallery forests: around 320 kilos per hectare. To do this, they have developed complex plot management systems, in terms of both time and space.

How do you set up cocoa plantings on grasslands?

The first step is to eradicate Imperata , a weed that is particularly harmful to crops. To do so, the farmers plant oil palms or annual crops. The former eradicate Imperata within six to eight years, while the latter take four to six years.

By sowing oil palms at high density, within four to five years, the farmers obtain a dense cover that prevents Imperata regrowth. They then reduce the number of palms and plant cocoa trees at a density of 1500 plants per hectare, along with fruit species such as oranges, bush butter trees, avocadoes and kola trees. They preserve or introduce some forest trees to provide the shade required for the young cocoa trees, and also to boost soil fertility. For a further two to three years, they weed the plots by hand until the tops of the trees provide continuous cover.

The other way of controlling Imperata is to sow short-cycle annual crops - groundnut, squash and maize - in manually ploughed plots. After two to three years, the farmers plant their cocoa trees and, as in the previous case, fruit trees and oil palms, keeping some forest trees. The annual crops are intercropped with the woody species for a further two to three years.

In both cases, the farmers then manage their plots so as to maintain shade to foster cocoa tree growth, while removing any surplus trees and replacing felled oil palms and diseased or dead cocoa trees. In this way, the agroforestry system gradually reaches a state of equilibrium.

Cultivating biodiversity and boosting soil fertility

The biodiversity of these cocoa plantings on grasslands tends to increase in the course of time: the Shannon-Weaver index increases from 1.97 in plantings less than ten years old to 2.26 in those more than forty years old. For instance, in a sample of 47 cocoa plantings, the researchers recorded almost 5000 intercropped trees from 67 species.

Soil fertility increases without applying fertilizers. Soil carbon content is 2.2% in ten-year-old plantings, compared to 1.7% in the neighbouring grasslands. It reaches 3.1% in plantings over forty years old.

These agroforestry systems enable farmers to restore degraded grassland soils and produce as much raw cocoa as in forest cocoa systems, without any inputs and in conditions that are theoretically unsuitable for cocoa.

These agroforestry practices could be a valid response to the climate change Africa is set to experience in the future, by maintaining production in a context that will be less favourable to cocoa growing.

CIRAD is a founder member of
Agreenium

Photos