# Effects of different tree species in an agroforestry parkland on soil fertility and maize yield in the Sudanese zone of Cameroon

Jacob Massai Tchima, Jean-Michel Harmand, Karel van den Meersche, Marie Sauvadet, Jules Bayala, Tchobsala Tchobsala, Ibrahima Adamou

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## ► To cite this version:

Jacob Massai Tchima, Jean-Michel Harmand, Karel van den Meersche, Marie Sauvadet, Jules Bayala, et al.. Effects of different tree species in an agroforestry parkland on soil fertility and maize yield in the Sudanese zone of Cameroon. World Congress on Agroforestry (WCA 2025), IUAF, Oct 2025, Kigali, Rwanda. pp.22. hal-05522840

HAL Id: hal-05522840

https://hal.science/hal-05522840v1

Submitted on 23 Feb 2026

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Distributed under a Creative Commons CC BY 4.0 - Attribution - International License
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Republic of Rwanda
Ministry of Environment

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6th World Congress on
# AGROFORESTRY

KIGALI-RWANDA, 20-24 OCTOBER 2025

Agroforestry for People, Planet & Profit

BOOK OF ABSTRACTS

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Preface

The 6th *World Congress on Agroforestry (WCA2025)* marks a pivotal moment in the global effort to advance agroforestry as a cornerstone of sustainable development. Held in Kigali, Rwanda, from 20–24 October 2025, the Congress convenes a diverse community of scientists, practitioners, policymakers, educators, farmers, and private sector actors united by a shared vision: harnessing the power of trees for people, planet, and profit.

Building on the momentum of previous congresses, WCA2025 provides a vital platform for dialogue, collaboration, and knowledge exchange across disciplines and regions. Under the main theme *Agroforestry for People, Planet & Profit*, participants explore how agroforestry can address some of the most pressing challenges of our time - land degradation, biodiversity loss, food insecurity, and climate change - while creating sustainable livelihoods and resilient landscapes.

This abstract book compiles the wide-ranging research, case studies, and innovations accepted for presentation at the Congress. The contributions reflect the dynamic and rapidly evolving nature of agroforestry, highlighting the integration of traditional knowledge with modern science and technology. The impressive response from authors worldwide underscores the growing recognition of agroforestry as a practical and scalable pathway toward ecological restoration and economic resilience.

The Congress program is organized around key thematic sessions, encompassing the contribution of agroforestry in a changing climate; its role in biodiversity and ecosystem services; livelihoods and sustainable food systems; bioeconomy; knowledge and innovation; financial and policy frameworks; silvopastoral systems; and multistrata perennial crop systems. Together, these themes capture the breadth and depth of contemporary agroforestry research and practice.

The organizers extend sincere appreciation to all contributors for their dedication, to reviewers for their critical insights, and to partners and sponsors for their steadfast support. It is our hope that the ideas and evidence presented in this collection will inspire further collaboration and innovation, helping shape policies and practices that secure a more sustainable and equitable future through agroforestry.

*World Congress on Agroforestry 2025 Secretariat*
Kigali, Rwanda
# Effects Of Different Tree Species in an Agroforestry Parkland on Soil Fertility and Maize Yield in The Sudanese Zone of Cameroon

Jacob Massaï Tchima<fnref n="1" />,<fnref n="2" />, Jean-Michel Harmand<fnref n="2" />,<fnref n="3" />,<fnref n="4" />, Karel Van den Meersche<fnref n="3" />,<fnref n="4" />, Marie Sauvadet<fnref n="3" />,<fnref n="4" />, Jules Bayala5, Tchobsala6, Ibrahima Adamou7

## Abstract.

In Africa, Sudano-Saharan farmers typically grow annual crops in diverse agroforestry parklands of variable tree densities. Parkland trees provide a variety of services, and their effects on soil properties and yields of associated crops are expected to be species-specific. This study was conducted in a parkland dominated by shea trees (Vitellaria paradoxa) in the village of Bame, located 52 km south of Garoua, in the Sudanese zone of the North Region of Cameroon (with an annual rainfall of 1012 mm). The study aimed to assess the effects of different tree species on soil properties and the yield of the associated maize in this parkland. The experimental design is based on 8 eightfarmers' plots containing the following seven agroforestry species: 6 species inherited from the previous tree savannah that was cleared about 40 years ago (Anogeissus leiocarpus, Burkea africana, Daniellia oliveri, Prosopis africana, Terminalia glaucescens, and V. paradoxa) and a 10-year-old planted species (Senna siamea) managed as a shrub with periodic pruning at the trunk base. The trees were partially pruned annually for fodder and/or firewood. The soil (Alfisol), derived from sandstone, was very sandy in the top layer, with less than 6% clay, and was poor in total carbon (C) and total nitrogen (N). Soil properties in the 0-10 cm layer and maize yield were assessed in 4 m<fnref n="2" /> subplots located at three positions: under the tree canopy, at the canopy edge, and in the open field. The subplots were selected South of the tree stems. All measured soil properties (pH, C, N, P Olsen, exchangeable Ca2+, K+, and Mg2+ contents) were generally improved under the tree canopies compared to the open field. All trees, most of which were pruned during the dry season, did not reduce crop yield when comparing maize yield under and at the edge of the canopy to that in the open field. On the contrary, a yield increase of more than 30% was observed under the canopy of P. africana, S. siamea, and T. glaucescens, compared with the open field. It is worth noting that canopy pruning reduced competition for light between trees and maize. Nutrient availability under the trees was positively correlated with maize yield. Furthermore, higher soil nitrification and nitrogen availability under the N2-fixing legume P. africana were associated with the significantly highest maize yield. This study demonstrated that parkland trees, which were inherited from old clearings and partially pruned annually, improved soil fertility under their canopy compared to the open field, without reducing maize yield during the observation period. Furthermore, contrasting effects between species on some soil properties and maize yield were observed, with a more substantial positive impact of the legume tree species on N availability and maize yield. Therefore, farmers should be encouraged to maintain parkland trees for soil conservation, crop production, and other benefits that trees provide.

<footnote n="1">¹Station polyvalente de recherche agricole de Garoua, IRAD, Garoua, Cameroon</footnote>

<footnote n="2">²World Agroforestry (CIFOR-ICRAF), Yaoundé, Cameroon</footnote>

<footnote n="3">³CIRAD, UMR Eco&Sols, Montpellier, France</footnote>

<footnote n="4">⁴Eco&Sols, Univ Montpellier, CIRAD, INRAE, IRD, Institut Agro, Montpellier, France</footnote>

<footnote n="5">⁵World Agroforestry (CIFOR-ICRAF) Ouagadougou, Burkina Faso</footnote>

<footnote n="6">⁶University of Maroua, Faculty of Science, Maroua, Cameroon</footnote>

<footnote n="7">⁷University of Ngaoundéré, Faculty of Science, Ngaoundéré, Cameroon</footnote>

<footnote>*Corresponding author: jacob.massai@yahoo.fr</footnote>