Long term impact of Acacia auriculiformis woodlots growing in rotation with cassava and maize on the carbon and nutrient contents of savannah sandy soils in the humid tropics (Democratic Republic of Congo)

Dubiez Emilien, Freycon Vincent, Marien Jean-Noël, Peltier Régis, Harmand Jean-Michel. 2019. Long term impact of Acacia auriculiformis woodlots growing in rotation with cassava and maize on the carbon and nutrient contents of savannah sandy soils in the humid tropics (Democratic Republic of Congo). Agroforestry Systems, 93 (3) : 1167-1178.

Quartile : Q2, Sujet : AGRONOMY / Quartile : Q2, Sujet : FORESTRY

Résumé : Rotational woodlots with N2-fixing trees may be efficient agroforestry systems, allowing farmers to alternate agricultural and wood-energy production on the same area. However, their long-term effect on soil fertility is poorly understood. The aim of this study was to investigate the influence of successive phases of Acacia auriculiformis stands growing in rotation with crops on the chemical properties of sandy and very poor tropical soils. The study was conducted 22 years after the afforestation of humid herbaceous savannah in Mampu, Democratic Republic of Congo. The chemical properties of top soil (0–20 cm) from control savannah plots were compared with those from acacia plots that had undergone one, two or three rotations of acacia during the 22 year period. We found that the soil properties under non-harvested acacia stands in a 1st rotation and under acacia stands in a 2nd or 3rd rotation following charcoal production and maize and cassava cultivation were similar. Soils under all acacia stands had higher C, N and NO−3–N contents, but were more acidic, and had lower contents of exchangeable Ca, Mg, K and Na than the control savannah soils. Despite the increase in soil C and N, the sustainability of the acacia rotational agroforestry system after 22 years of practice is in question due to the steady decrease of soil cations, soil acidification and the risk of a decline in tree and crop productivity. To improve the nutrient balance and the sustainability of this system, different practices are recommended such as the debarking of tree stems before carbonization, the restitution of small branches and charcoal residues to the soil, and the supply of natural rock phosphate.

Mots-clés Agrovoc : Acacia auriculiformis, agroforesterie, manioc, maïs, culture associée, arbre fixateur d'azote, rotation culturale, fertilité du sol, transport des substances nutritives, Fixation de l'azote, cycle du carbone, sol sableux, savane, Arénosol

Mots-clés géographiques Agrovoc : Afrique centrale, République démocratique du Congo

Mots-clés libres : Bateke Plateau, Agroforestry, Arenosol, Charcoal production, Shifting cultivation, N2 fixation

Classification Agris : F08 - Systèmes et modes de culture
K10 - Production forestière
F61 - Physiologie végétale - Nutrition
P33 - Chimie et physique du sol

Champ stratégique Cirad : CTS 2 (2019-) - Transitions agroécologiques

Auteurs et affiliations

• Dubiez Emilien, CIRAD-ES-UPR Forêts et sociétés (FRA) ORCID: 0000-0002-7097-5263 - auteur correspondant
• Freycon Vincent, CIRAD-ES-UPR Forêts et sociétés (FRA)
• Marien Jean-Noël, Université de Montpellier (FRA)
• Peltier Régis, CIRAD-ES-UPR Forêts et sociétés (FRA) ORCID: 0000-0002-8110-7322
• Harmand Jean-Michel, CIRAD-PERSYST-UMR Eco&Sols (CMR) ORCID: 0000-0002-8065-106X

Source : Cirad-Agritrop (https://agritrop.cirad.fr/587477/)

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