Absorption of (NH3)-N-15 volatilized from urea by Citrus trees

Autor(es)

Boaretto, Rodrigo M. ^[1] ; Mattos, Jr., Dirceu ^[1] ; Quaggio, Jose A. ^[2] ; Cantarella, Heitor ^[2] ; Trivelin, Paulo C. O. ^[3]

Afiliação do(s) autor(es)

^[1] Ctr Citricultura Sylvio Moreira, Inst Agron, BR-13490970 Cordeiropolis, SP - Brazil

^[2] Ctr Solos & Recursos Ambientais, Inst Agron, BR-13020902 Campinas, SP - Brazil

^[3] Univ Sao Paulo, Ctr Energia Nucl Agr, BR-13400970 Piracicaba, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: PLANT AND SOIL; v. 365, n. 1-2, p. 283-290, APR 2013.
• Citações Web of Science: 7

Resumo

Gaseous losses of ammonia (NH3) have been observed in citrus orchards when urea is surface-applied to the soils, and this loss might significantly limit the effectiveness of the nitrogen (N) fertilizer. However, a portion of the volatilized NH3 might be absorbed by the plants through the leaves. To quantify the contribution of the leaf absorption of (NH3)-N-15, a study with sweet oranges was conducted in two field areas where trees were grown at standard (480 trees ha(-1)) and high densities (617 trees ha(-1)). Plastic trays were filled with soil, covered with mown grass to simulate field management conditions, fertilized with N-15 labeled urea (12 atom % excess) and placed under each of three trees in the orchards. This experimental procedure prevented the uptake of N from the labeled urea by the roots. Two weeks after N-15 fertilization, the trays were removed from the field, and the soil was homogenized and sampled for chemical analyses. The citrus trees under which the trays were placed were destructively harvested, and the total N concentrations and N-15/N-14 ratios were determined. After urea application, the NH3 losses peaked within three days and subsequently decreased to negligible amounts after 10 days. The total NH3 losses accounted for 55-82 % of the applied N. Although the NH3 absorption by the citrus leaves was proportional to the tree density in the field, only 3-7 % of the (NH3)-N-15 volatilized from the soil was recovered by the citrus trees, and the NH3 absorption was also influenced by the proximity of citrus trees to the site of urea application and the leaf areas of the trees. The citrus trees can absorb the NH3 volatilized from urea, even though, the amount recovered by the trees is small and does not represent a significant proportion of total gaseous N losses, what demonstrates the importance of enhanced N use efficiency practices in field to reduce losses of NH3 when urea is applied to soil surfaces. (AU)

• Processo FAPESP: 06/56667-0 - Uso de técnicas isotópicas (15N) na identificação de reservatórios do nitrogênio absorvido e sua redistribuição em duas espécies de citros e absorção foliar da amônia volatilizada da uréia fertilizante
• Beneficiário: Jose Antonio Quaggio
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 06/56666-3 - Uso de tecnicas isotopicas (15n) na identificacao de reservatorios do nitrogenio absorvido e sua redistribuicao em duas especies de citros e absorcao foliar da amonia volatilizada da ureia fertilizante.
• Beneficiário: Rodrigo Marcelli Boaretto
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado