CONTEXT

Cocoa agroforestry systems differ in the diversity of shade tree species composition. Though cocoa benefits from shade, there is a lack of species-specific information on shade trees that enhance soil fertility and yield.

OBJECTIVE

We examined how soil characteristics and cocoa yield were affected by eight commonly retained forest tree species, compared with unshaded control plots over a 3-year period.

METHODS

Using 74 circular plots from 10 cocoa farms in the Western region of Ghana, we sampled soils from two random points within each plot. Soil nutrients at the beginning and end of the study were analyzed, and yield was expressed as number of harvested pods and dry weight of beans per hectare.

RESULTS AND CONCLUSIONS

Levels of soil K and Ca were below recommended values. Although soil available phosphorus (P) was higher in control plots than under shade trees, yield around shade trees were higher than on unshaded plots. Cocoa yield differences between shade tree species and control plots were significant only in the major crop season, but not in the minor crop season. Cocoa yields under Cedrela odorata, Khaya ivorensis, Terminalia superba and Milicia excelsa were significantly higher than on control plots. Hence, the inclusion of specific shade tree species in cocoa agroforestry systems is important to maintain high yields in cocoa systems with low inputs.

SIGNIFICANCE

To our knowledge, this study presents one of the first attempt to assess the impacts of specific shade tree species on soil characteristics and cocoa yield.

中文翻译：

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选定的遮荫树种提高了加纳低投入农林业系统的可可产量

语境

可可农林业系统在遮荫树种组成的多样性方面存在差异。虽然可可受益于遮荫，但缺乏关于提高土壤肥力和产量的遮荫树的特定物种信息。

客观的

我们研究了土壤特性和可可产量如何受到八种常见保留森林树种的影响，与 3 年期间的无阴影对照地块进行比较。

方法

我们使用来自加纳西部地区 10 个可可农场的 74 个圆形地块，从每个地块内的两个随机点取样土壤。分析了研究开始和结束时的土壤养分，产量以每公顷收获的豆荚数和豆类干重表示。

结果和结论

土壤钾和钙含量低于推荐值。尽管对照样地的土壤有效磷 (P) 高于遮荫地，但遮荫树周围的产量高于无遮荫地。遮荫树种和对照地块之间的可可产量差异仅在主要作物季节显着，但在次要作物季节不显着。Cedrela odorata、Khaya ivorensis、榄仁树和Milicia excelsa下的可可产量显着高于对照地块。因此，在可可农林业系统中加入特定的遮荫树种对于在低投入的可可系统中保持高产非常重要。

意义

据我们所知，这项研究首次尝试评估特定遮荫树种对土壤特性和可可产量的影响。