Florence Tardy, Jean-Pierre Bouillet, Jean-Paul Laclau, Marcelo Zacharias Moreira, D.R.M. Caldeira, José Leonardo de Moraes Gonçalves, Fernando Palha Leite, Carolina B. Brandani, Maureen Voigtlaender, Ranieri Ribeiro Paula, Didier Brunet, Universidade de São Paulo (USP), Universidade Estadual Paulista Júlio de Mesquita Filho = São Paulo State University (UNESP), Ecologie fonctionnelle et biogéochimie des sols et des agro-écosystèmes (UMR Eco&Sols), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA), Centro de Energia Nuclear na Agricultura (CENA ), University of São Paulo (USP), Celulose Nipo-Brasileira SA (CENIBRA), Universidade Federal do Espirito Santo (UFES), Cenibra, International Paper, Suzano Papel e Celulose, SOERE F-ORE-T network, which is supported annually by Ecofor, Allenvi and the French National Research Infrastructure ANAEE-F, Universidade Estadual Paulista (Unesp), UMR Eco&Sols, University of Montpellier, Coordenação de Pesquisa Florestal, UFES, Universidade de São Paulo = University of São Paulo (USP), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Département Performances des systèmes de production et de transformation tropicaux (Cirad-PERSYST), and Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)
Made available in DSpace on 2019-10-06T15:31:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-03-15 Mixing N-fixing trees with eucalypts is an attractive option to improve the long-term soil N status in fast-growing plantations established in tropical soils. A randomized block design was replicated at four sites in Brazil to compare the biogeochemical cycles in mono-specific stands of Eucalyptus (100E) and Acacia mangium (100A) with mixed-species plantations in a proportion of 1:1 (50A50E). Our study aimed to assess the effects of introducing A. mangium trees in Eucalyptus plantations on atmospheric N 2 fixation, N cycling and soil organic matter stocks. Litterfall and soil N mineralization were measured over the last two years of the rotation (4–6 years after planting). Aboveground N accumulation in the trees and C and N stocks in the forest floor and in the top soil were intensively sampled at harvesting age. N 2 fixation rates were estimated using the natural abundance of 15 N as well as by the difference between total N stocks in 100A and 50A50E relative to 100E (accretion method). While the 15 N natural abundance method was unsuitable, the accretion method showed consistently across the four sites that atmospheric N fixation reached about 250 and 400 kg N ha −1 rotation −1 in 50A50E and 100A, respectively. Except at one site with high mortality, N contents within trees at harvesting were approximately 40% higher in 100A than in 100E. Mean N contents in litterfall and N mineralization rates were about 60% higher in 100A than in 100E, with intermediate values in 50A50E. The amounts of N in litterfall were much more dependent on soil N mineralization rates for acacia trees than for eucalypt trees. Soil C and N stocks were dependent on soil texture but not influenced by tree species. N budgets over a 6-year rotation were enhanced by about 65 kg N ha −1 yr −1 in 100A and 40 kg N ha −1 yr −1 in 50A50E relative to monospecific eucalypt plantations. Introducing N-fixing trees in eucalypt plantations might therefore contribute to reducing the need for mineral N fertilization in the long-term. USP ESALQ Forest Science Department UNESP Departamento de Solos e Recursos Ambientais Universidade Estadual Paulista ‘Júlio de Mesquita Filho’ CIRAD UMR Eco&Sols Eco&Sols INRA CIRAD IRD Montpellier SupAgro University of Montpellier USP CENA, Av. Centenário, 303 CENIBRA Coordenação de Pesquisa Florestal, 35196-972 Belo Oriente Department of Forest Science and Wood UFES, 29550-000 Jerônimo Monteiro UNESP Departamento de Solos e Recursos Ambientais Universidade Estadual Paulista ‘Júlio de Mesquita Filho’