Shade tree effects in an 8-year-old cocoa agroforestry system: biomass and nutrient diagnosis of Theobroma cacao by vector analysis

Farm product diversification, shadeprovision and low access to fertilizers often resultin the purposeful integration of upper canopytrees in cocoa (Theobroma cacao) plantations.Subsequent modification to light and soil condi-tions presumably affects nutrient availability andcocoa tree nutrition. However, the level ofcomplementarity between species requires inves-tigation to minimize interspecific competition andimprove resource availability. We hypothesizedbeneficial effects of upper canopy trees on cocoabiomass, light regulation, soil fertility and nutri-ent uptake. We measured cocoa standing biomassand soil nutrient stocks under no shade (mono-culture) and under three structurally and func-tionally distinct shade trees:Albizia zygia(D.C.)Macbr, a nitrogen fixer;Milicia excelsa(Welw.), anative timber species; andNewbouldia laevis(Seem.), a native small stature species. Vectoranalysis was employed to diagnosis tree nutrition.Cocoa biomass was higher under shade (22.8 forsole cocoa versus 41.1 Mg ha–1for cocoa underMilicia), and declined along a spatial gradientfrom the shade tree (P< 0.05). Percent canopyopenness differed between the three shade spe-cies (P= 0.0136), although light infiltration waswithin the optimal range for cocoa productionunder all three species. Soil exchangeable K wasincreased underNewbouldia, while available Pdecreased and total N status was unaffected underall shade treatments. Nutrient uptake by cocoaincreased under shade (43–80% and 22–45% forN and P, respectively), with K (96–140%) as themost responsive nutrient in these multistratasystems. Addition of low-density shade treespositively affected cocoa biomass close to theshade tree, however proper management of upperstratum trees is required for optimum cocoaproductivity and sustainability.

Bibliographic Details

Main Authors:	79925 Isaac, M.E., 124506 Timmer, V.R., 107706 Quashie-Sam, S.J. autores/as
Format:	biblioteca
Language:	eng
Published:	Amsterdam (Países Bajos): Springer, 2007
Subjects:	SOMBRA, BIOMASA, ABSORCION DE SUSTANCIAS NUTRITIVAS, FERTILIDAD DEL SUELO, PLANTAS DE SOMBRA, GHANA, INVESTIGACION EN LA FINCA, THEOBROMA CACAO, AGROFORESTERIA,
Online Access:	https://doi.org/10.1007/s10705-006-9081-3
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