N2 fixation by two lupine species under different soil management systems: Transfer of fixed N2 from legume to intercropped eucalyptus

• Autor(a) principal: Carranca,Corina
• Data de Publicação: 2013
• Outros Autores: Madeira,Manuel, Torres,Maria Odete
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://scielo.pt/scielo.php?script=sci_arttext&pid=S0871-018X2013000100010
• topic: Haplic Podzols; harvest residues; Lupinus albus and Lupinus luteus; N benefit; tillage

The rate and pattern of symbiotic fixation and N credit by white lupine as affected by soil tillage, and yellow lupine affected by soil amendment with eucalyptus harvest residues were evaluated; also, fixed N transferred from yellow lupine to the intercropped eucalyptus was assessed. Lupine species growing in sandy soils with low nutrient status fixed >94% N2 with the indigenous soil rhizobium, in two sites (Pegões, Óbidos). Soil disturbance and harvest residues incorporation did not affect the fixing capacity of both lupines. Positive N inputs (>+69 kg N ha-1) were estimated for both lupines, which is relevant in a rotation or association with non-legume crops. Nitrogen concentration in newly-planted eucalyptus was 23% lower in harvest residues amended soil and 36% greater by the addition of mineral-15N compared with organic fertilization (yellow lupine). Mineral-N use efficiency by eucalyptus seedlings was low (4%) which may be associated with the small root development (shoot:root ratio=4.3). Organically fertilized trees showed 15N enrichment thirteen times smaller than mineral-15N fertilized trees.