Effect of Biological Amendment on the Agro-morphology of Cocoa Companion Species (Irvingia gabonensis, Garcinia kola, Tieghemella heckelii and Beilschmiedia mannii) at the Nursery Stage

The use of organic amendments plays a crucial role in improving soil fertility and enhancing plant growth in agroforestry systems. This study evaluates the impact of different organic amendments on the morphophysiological parameters of four companion species of cocoa (Irvingia gabonensis (Kplé), Garcinia kola (Petit cola), Tieghemella heckelii (Makoré) and Beilschmiedia mannii (Bitéi)) at the juvenile stage. The aim is to determine the most effective amendment for promoting vegetative growth, biomass accumulation and photosynthetic activity.

The research was carried out on the experimental farm of ICRAF located in the La Mé region. Four treatments were set up: T0, which consisted of soil taken from the top 10 cm of an old cocoa plantation; T1, a blend of two-thirds T0 soil and one-third rice husk biochar; T2, which comprised T0 soil enriched with 0.5 kg of composted poultry manure and T3, a balanced mix of T1 and T2.

The results highlight that treatments T0 and T2 stand out due to their significant positive effects on overall vegetative growth, biomass production and the enhancement of photosynthetic activity. In particular, the enriched compost (T2) demonstrated remarkable efficacy in improving plant performance, underscoring its potential as a preferred amendment for crop cultivation. Although biochar (T1) showed lower performance on some global indicators, it exhibited specific and noteworthy effects, particularly on root development and leaf chlorophyll content.