Distribution of coarse and fine roots of Theobroma cacao and shade tree Inga edulis in a cocoa plantation
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Cocoa (Theobroma cacao L.) is often cultivated below legume shade trees, but root interactions between the species are not well known. The first step in understanding these interactions is the description of spatial root system distribution of cocoa and shade trees.
We studied the root distributions of cocoa and Inga edulis Mart. (inga) in an agroforestry plantation in the humid tropics of Costa Rica.
Fine roots were sampled by soil coring, and a fractal root architecture model parameterised with data from partial root excavations was used for determining coarse root distribution.
Fine root length in the 0–50 cm soil layer was 26,762 and 22,026 km ha−1 for cocoa and inga, respectively, with 24 % and 23 % of fine root length of cocoa and inga, respectively, in the 0–2 cm layer. Horizontally, root distributions of the two species with cocoa at 3 × 3 m and inga at 9 × 9 m spacing overlapped strongly, while inga did not cover all points at 18 × 18 m spacing.
Both species seem to efficiently capture nutrients released from the litter layer on the soil surface, and nutrient leaching in shaded cocoa plantations is unlikely. The proximity of root systems may facilitate N exchange between the N2-fixing inga and cocoa, but competition for other nutrients is likely.
KeywordsAgroforestry Fractal networks Organic farming Resource sharing Root architecture Root length
We thank Mr. Ricardo Palacios, the farm manager, for accommodating our research with cocoa cultivation in the plantations, Mr. Miika Kurppa for supervising the coarse root measuring team and Mr. Oscar Gayle for assisting in fine root sampling and processing.
The study was funded by the Academy of Finland (grant 129166) and the EARTH University Research Committee.
- Atger C, Edelin C (1994b) Stratégies d’occupation du milieu souterrain par les systèmes racinaires des arbres. Rev Ecol (Terre Vie) 49:343–356Google Scholar
- Gold MA, Rietveld WJ, Garrett HE, Fisher RF (2000) Agroforestry nomenclature, concepts, and practices for the USA. In: Garrett HE, Rietveld WJ, Fisher RF (eds) North American agroforestry: an integrated science and practice. American Society of Agronomy, Madison, pp 63–77Google Scholar
- Gómez Luciano CA (2008) Distribución de Raíces Finas de Inga edulis y Theobroma cacao en el Suelo de un Sistema Agroforestal Orgánico. Proyecto de Graduación. Universidad EARTH, Guácimo, p 17Google Scholar
- Jonsson K, Fidjeland L, Maghembe JA, Högberg P (1988) The vertical distribution of fine roots of five tree species and maize in Morogoro, Tanzania. Agrofor Sys 6:63–69Google Scholar
- Mogollón Frasca BA (2007) Efecto de la disponibilidad de nitrato y amonio, en la distribución de raíces en un sistema agroforestal. Proyecto de Graduación. Universidad EARTH, Guácimo, p 26Google Scholar
- Smith SE, Read DJ (2008) Mycorrhizal symbiosis, 3rd edn. Academic, New York, p 787Google Scholar
- van Noordwijk M (1993) Roots: length, biomass, production and mortality. In: Anderson JM, Ingram JSI (eds) Tropical soil biology and fertility: a handbook of methods. CAB International, Wallingford, pp 132–144Google Scholar
- van Noordwijk M, Lawson G, Soumaré A, Groot JJR, Hairiah K (1996) Root distribution of trees and crops: competition and/or complementarity. In: Ong CK, Huxley P (eds) Tree–crop interactions: a physiological approach. CAB International, Wallingford, pp 319–364Google Scholar