caa a22 4500 463209095 CHVBK 20180405153135.0 cr unu---uuuuu 170326e20070601xx s 000 0 eng 10.1007/s10705-006-9081-3 doi (NATIONALLICENCE)springer-10.1007/s10705-006-9081-3 Shade tree effects in an 8-year-old cocoa agroforestry system: biomass and nutrient diagnosis of Theobroma cacao by vector analysis [Elektronische Daten] [M. Isaac, V. Timmer, S. Quashie-Sam] Farm product diversification, shade provision and low access to fertilizers often result in the purposeful integration of upper canopy trees in cocoa (Theobroma cacao) plantations. Subsequent modification to light and soil conditions presumably affects nutrient availability and cocoa tree nutrition. However, the level of complementarity between species requires investigation to minimize interspecific competition and improve resource availability. We hypothesized beneficial effects of upper canopy trees on cocoa biomass, light regulation, soil fertility and nutrient uptake. We measured cocoa standing biomass and soil nutrient stocks under no shade (monoculture) and under three structurally and functionally distinct shade trees: Albizia zygia (D.C.) Macbr, a nitrogen fixer; Milicia excelsa (Welw.), a native timber species; and Newbouldia laevis (Seem.), a native small stature species. Vector analysis was employed to diagnosis tree nutrition. Cocoa biomass was higher under shade (22.8 for sole cocoa versus 41.1Mgha−1 for cocoa under Milicia), and declined along a spatial gradient from the shade tree (P<0.05). Percent canopy openness differed between the three shade species (P=0.0136), although light infiltration was within the optimal range for cocoa production under all three species. Soil exchangeable K was increased under Newbouldia, while available P decreased and total N status was unaffected under all shade treatments. Nutrient uptake by cocoa increased under shade (43-80% and 22-45% for N and P, respectively), with K (96-140%) as the most responsive nutrient in these multistrata systems. Addition of low-density shade trees positively affected cocoa biomass close to the shade tree, however proper management of upper stratum trees is required for optimum cocoa productivity and sustainability. Springer Science+Business Media B.V., 2007 Ghana nationallicence Light availability nationallicence Multistrata system nationallicence Nutrient uptake nationallicence On-farm research nationallicence Soil fertility nationallicence Isaac M. Faculty of Forestry, University of Toronto, 33 Willcocks St., Earth Science Centre, M5S 3B3, Toronto, Canada aut Timmer V. Faculty of Forestry, University of Toronto, 33 Willcocks St., Earth Science Centre, M5S 3B3, Toronto, Canada aut Quashie-Sam S. Faculty of Renewable Natural Resources, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana aut Nutrient Cycling in Agroecosystems Kluwer Academic Publishers 78/2(2007-06-01), 155-165 1385-1314 78:2<155 2007 78 10705 https://doi.org/10.1007/s10705-006-9081-3 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10705-006-9081-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Isaac M. Faculty of Forestry, University of Toronto, 33 Willcocks St., Earth Science Centre, M5S 3B3, Toronto, Canada aut NATIONALLICENCE 700 1- Timmer V. Faculty of Forestry, University of Toronto, 33 Willcocks St., Earth Science Centre, M5S 3B3, Toronto, Canada aut NATIONALLICENCE 700 1- Quashie-Sam S. Faculty of Renewable Natural Resources, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana aut NATIONALLICENCE 773 0- Nutrient Cycling in Agroecosystems Kluwer Academic Publishers 78/2(2007-06-01), 155-165 1385-1314 78:2<155 2007 78 10705 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer