| Autor(es): |
Rocha, Kassiano F.
[1]
;
de Souza, Murilo
[1]
;
Almeida, Danilo S.
[1]
;
Chadwick, David R.
[2]
;
Jones, Davey L.
[2, 3]
;
Mooney, Sacha J.
[4]
;
Rosolem, Ciro A.
[1]
Número total de Autores: 7
|
| Afiliação do(s) autor(es): | [1] Sao Paulo State Univ, Sch Agr Sci, Dept Crop Sci, Univ Av 3780, BR-18610034 Botucatu, SP - Brazil
[2] Bangor Univ, Sch Nat Sci, Bangor LL57 2UW, Gwynedd - Wales
[3] Univ Western Australia, UWA Sch Agr & Environm, Crawley, WA 6009 - Australia
[4] Univ Nottingham, Fac Sci, Div Agr & Environm Sci, Sutton Bonington Campus, Loughborough LE12 SRB, Leics - England
Número total de Afiliações: 4
|
Part of the nitrogen (N) fertilizer applied to crops is lost to the environment, contributing to global warming, eutrophication, and groundwater contamination. However, low N supply stimulates soil organic N turnover and carbon (C) loss, since the soil N/C ratio in soil is quasi-constant, ultimately resulting in land degradation. Grasses such as ruzigrass (Urochloa ruziziensis) grown as winter pasture or a cover crop in rotation with maize (Zea mays) can reduce N leaching, however, this may induce N deficiency and depress yields in the subsequent maize crop. Despite the potential to decrease N loss, this rotation may negatively affect the overall N balance of the cropping system. However, this remains poorly quantified. To test this hypothesis, maize, fertilized with zero to 210 kg N ha(-1), was grown after ruzigrass, palisade grass (Urochloa brizanta) and Guinea grass (Pannicum maximum), and the N inputs, outputs and partial N balance determined. Despite the intrinsically poor soil quality associated with the tropical Ultisol, maize grown after the grasses was efficient in acquiring N, resulting in a negative N balance even when 210 kg ha(-1) of N was applied after Guinea grass. Losses by leaching, N2O emission and NH3 volatilization did not exceed 13.8 kg ha(-1) irrespective of the grass type. Despite a similar N loss among grasses, Guinea grass resulted in a higher N export in the maize grain due to a higher yield, resulting in a more negative N balance. Soil N depletion can lead to C loss, which can result in land degradation. (AU) |