Emissions of CO sub(2), N sub(2)O, and NO in conventional and no-till management practices in Rondonia, Brazil

Efforts to restore productivity of pastures often employ agricultural management regimes involving either tillage or no-tillage options combined with various combinations of fertilizer application, herbicide use and the planting of a cash crop prior to the planting of forage grasses. Here we report...

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Bibliographic Details
Published in:Biology and fertility of soils 2003-08, Vol.38 (4), p.200-208
Main Authors: Passianoto, C C, Ahrens, T, Feigl, B J, Steudler, P A, do Carmo, JB, Melillo, J M
Format: Article
Language:English
Subjects:
Brachiaria brizantha
Oryza sativa
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Summary:Efforts to restore productivity of pastures often employ agricultural management regimes involving either tillage or no-tillage options combined with various combinations of fertilizer application, herbicide use and the planting of a cash crop prior to the planting of forage grasses. Here we report on the emissions of CO sub(2), N sub(2)O and NO from the initial phases (first 6 months) of three treatments in central Rondonia. The treatments were (1) control; (2) conventional tillage followed by planting of forage grass (Brachiaria brizantha) and fertilizer additions; (3) no-tillage/herbicide treatment followed by two plantings, the first being a cash crop of rice followed by forage grass. In treatment 3, the rice was fertilized. Relative to the control, tillage increased CO sub(2) emission by 37% over the first 2 months, while the no-tillage/herbicide regime decreased CO sub(2) emissions by 7% over the same period. The cumulative N sub(2)O emissions over the first 2 months from the tillage regime (0.94 kg N ha super(-1)) were much higher than the N sub(2)O releases from either the no-tillage/herbicide regime (0.64 kg N ha super(-1)) or the control treatment (0.04 kg N ha super(-1)). The highest levels of N sub(2)O fluxes from both management regimes were observed following N fertilizations. The cumulative NO releases over the first 2 months were largest in the tillage treatment (0.98 kg N ha super(-1)), intermediate in the no-tillage treatment (0.72 kg N ha super(-1)), and smallest in the control treatment (0.12 kg N ha super(-1)). For the first week following fertilization the percentage of fertilizer N lost as N sub(2)O plus NO was 1.0% for the tillage treatment and 3.0% for the no-tillage treatment.
ISSN:0178-2762