Purpose

Although litter decomposition and nutrient release patterns have been studied in cocoa agroforestry systems in general, studies focusing on organic and conventional cocoa systems are lacking which is critical as organic farms are particularly dependent on nutrient returns from decomposing litter.

Materials and methods

Dynamics in leaf litter decomposition and the mineralisation of macro- and micro-nutrients in organic and conventional cocoa agroforestry systems were studied using the litterbag technique for 12 months.

Results

The average monthly mass loss was more than two times higher on organic farms (9.2–14.4 g month⁻¹) compared to conventional farms (4.2–7.3 g month⁻¹) in the first five months. The annual rate of decomposition (k) was higher on organic farms (1.9) compared to conventional systems (1.4). The time required for 50% (t₅₀) and 99% (t₉₉) decomposition of leaf litter was both lower on organic farms (t₅₀ = 0.4 years, t₉₉ = 2.6 years) than conventional farms (t₅₀ = 0.5 years, t₉₉ = 3.5 years). The estimated k values for macro- and micro-nutrients on organic cocoa systems ranged from 2.3 for calcium to 4.5 for potassium compared to 1.6 (Ca) to 2.8 (K) on conventional farms. The k values of all nutrients (except nitrogen and phosphorus) were significantly greater on organic farms than conventional systems. The estimated k values for both litter decomposition and nutrient mineralisation correlated with soil pH and moisture content, but not initial litter chemistry.

Conclusions

Organic management of smallholder cocoa agroforestry systems enhanced leaf litter decomposition and nutrient mineralisation through improved soil conditions. Thus, organic management of cocoa agroforestry systems may contribute to sustainable cocoa production in smallholder systems through enhanced nutrient return from litter decomposition.

中文翻译：

---

小农可可农林中凋落物的分解和养分矿化：加纳有机农场和常规农场的比较

目的

尽管总体上已经在可可农林业系统中研究了凋落物分解和养分释放模式，但是缺乏针对有机和常规可可系统的研究，这是至关重要的，因为有机农场特别依赖于分解凋落物的养分返回。

材料和方法

使用垃圾袋技术研究了有机和常规可可农林业系统中叶片凋落物分解的动态以及大量和微量营养元素的矿化，历时12个月。

结果

在头五个月中，有机农场（9.2–14.4 g month ^-1）的平均月质量损失比传统农场（4.2–7.3 g month ^-1）高出两倍以上。与传统系统（1.4）相比，有机农场的年分解率（k）更高（1.9）。有机农场（t ₅₀  = 0.4年，t ₉₉  = 2.6年）上，凋落物分解的50％（t ₅₀）和99％（t ₉₉）所需的时间均比传统农场（t ₅₀  = 0.5年，t ₉₉  = 3.5年）。估计的k有机可可系统中宏观和微量营养素的含量范围从钙的2.3到钾的4.5相比，传统农场的从1.6（Ca）到2.8（K）。有机农场的所有养分（氮和磷除外）的k值均显着高于传统系统。凋落物分解和养分矿化的估计k值与土壤pH和水分含量相关，但与最初的凋落物化学性质无关。

结论

小农可可农林业系统的有机管理通过改善土壤条件促进了凋落物分解和养分矿化。因此，可可农林业系统的有机管理可通过提高凋落物分解的养分返回来促进小农系统中可可的可持续生产。