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Cocoa-based agroforestry vs fallow: what option for soil quality regeneration in the Peruvian amazon?

Deheuvels O., Saj S., Xavier-Rousseau G., Valverde J., Robiglio V.. 2017. In : Booklet of abstracts of the first International Symposium on Cocoa Research ISCR 2017. Lima : ICCO, p. 273-274. International Symposium on Cocoa Research – ISCR 2017 : Promoting Advances in Research to Enhance the Profitability of Cocoa Farming. 1, 2017-11-13/2017-11-17, Lima (Pérou).

In the Peruvian Amazon, a significant amount of the agricultural landscape is cultivated with cocoa (Theobroma cacao) mostly grown under the shade of Musacea and timber trees. There, deforestation and its control are one of the main environmental issues for the Peruvian government and further, for the international community. In these landscapes, farmers who want to establish new plantations have the choice between tropical forest and degraded lands. Most of the latest are abandoned pastures or annual crops with mostly red ferralitic soils heavily unsaturated. As a response to the loss of fertility, farmers have currently two alternatives: entering illegally into the natural forest or practicing shifting cultivation on a long term basis that can reach more than 15 years. In this last case, the fallow lands, locally called “Purma”, are named under three categories according to the height of the pioneer vegetation: (i) low (10 years). Our study has been conducted with former coca farmers moved 20 years ago by the Peruvian government to the Ucayali department to produce cocoa. There, we compared soil quality, cadmium content and plant biomass including fine roots at 0-20 and 20-50 cm depth, among three land uses: (i) 31 agroforestry cocoa plantations at different ages, (ii) 24 low, 24 medium and 22 high “purmas”, and finally (iii) 22 forest patches as a control. Our results provide an interesting basis to discuss the ability of cocoa-based agroforestry systems to maintain and even restore soil fertility in degraded landscape at the Amazonian forest margin. The evolution of Cadmium content depending on land use and fallow period gives interesting indications for further investigations.

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