Planting nitrogen-fixing trees in tropical Eucalyptus plantations does not increase nutrient losses through drainage

Formaglio Greta, Krusche Alex Vladimir, Mareschal Louis, Bouillet Jean-Pierre, De Moraes Gonçalves Jose Leonardo, Nouvellon Yann, Delgado-Rojas Juan Sinforiano, Montebelo Alexandra, Ranger Jacques, Laclau Jean-Paul. 2023. Planting nitrogen-fixing trees in tropical Eucalyptus plantations does not increase nutrient losses through drainage. Forest Ecology and Management, 537:120940, 11 p.

Résumé : Planting nitrogen (N) fixing species can provide substantial levels of N for tree growth, but it can also result in large nutrient losses through deep drainage, threatening soil fertility. Nutrient losses through deep leaching have been little studied in tropical forest plantations and comprehensive studies are needed before planting these species on a large scale. We assessed nutrient fluxes in soil solutions collected in monocultures and mixed plantations of Acacia mangium and Eucalyptus grandis in Sao Paulo state (Brazil) on Ferralsols fertilized with potassium, phosphorus and lime. Soil solution sampling began after replanting the trees in an experiment that had already been conducted for six years in a first rotation. We collected soil solutions beneath the forest floor and at depths of 30, 100 and 300 cm, and determined nutrient concentrations monthly for 3.5 years. Drainage fluxes were calculated at the depth of the lysimeters by modeling the water fluxes with Hydrus 1D. The N concentrations in topsoil solutions were generally higher in Acacia than in Eucalyptus monocultures, confirming that the introduction of Acacia increases soil N availability. However, these differences were no more observed at 100 cm depth and total N leaching at 300 cm depth was low in all the treatments, with an average of 4.8 kg N ha−1 yr−1, probably due to the rapid root system development and high nutrient requirements of these fast-growing trees. Leaching fluxes of K+, Cl−, Ca2+ and Mg2+ peaked in the upper soil layers after fertilizer applications, but the fluxes drastically decreased in deep soil layers. The low fluxes of dissolved nutrients in deep gravitational solutions in our study suggest that the risks of nutrient leaching losses are low in fast-growing plantations established on deep Ferralsols. Our results show that planting N-fixing trees can enhance the N availability for plants without producing large leaching losses, which confirms the interest of mixed plantations with N-fixing trees.

Mots-clés Agrovoc : Eucalyptus grandis, arbre fixateur d'azote, fertilisation, fertilité du sol, Acacia mangium, plantation forestière, croissance, substance nutritive, système racinaire, forêt tropicale, sol tropical, lessivage du sol, Eucalyptus

Mots-clés géographiques Agrovoc : Brésil, Sao Paulo

Mots-clés libres : Acacia mangium, Mixed-species plantations, Drainage, Soil solution, Nutrient leaching, Brazil

Classification Agris : K01 - Foresterie - Considérations générales
F61 - Physiologie végétale - Nutrition

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

Agences de financement hors UE : Agence Nationale de la Recherche, Fundação de Amparo à Pesquisa do Estado de São Paulo

Projets sur financement : (FRA) Intensification écologique des écosystèmes de plantations forestières. Modélisation biophysique et évaluation socio-économique de l'association d'espèces fixatrices d'azote

Auteurs et affiliations

• Formaglio Greta, CIRAD-PERSYST-UMR Eco&Sols (FRA)
• Krusche Alex Vladimir, CENA (BRA)
• Mareschal Louis, CIRAD-PERSYST-UMR Eco&Sols (FRA)
• Bouillet Jean-Pierre, CIRAD-PERSYST-UMR Eco&Sols (MDG)
• De Moraes Gonçalves Jose Leonardo, USP (BRA)
• Nouvellon Yann, CIRAD-PERSYST-UMR Eco&Sols (FRA) ORCID: 0000-0003-1920-3847
• Delgado-Rojas Juan Sinforiano, Agro Ambiência Serviços Agrícolas (BRA)
• Montebelo Alexandra, CENA (BRA)
• Ranger Jacques, Académie d'agriculture de France (FRA)
• Laclau Jean-Paul, CIRAD-DG-Direction générale (FRA) ORCID: 0000-0002-2506-214X - auteur correspondant

Source : Cirad-Agritrop (https://agritrop.cirad.fr/604240/)

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