1. Nitrous oxide and ammonia emissions from N fertilization of maize crop under no-till in a Cerrado soil.
- Author
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Martins, Márcio R., Jantalia, Cláudia P., Polidoro, José C., Batista, Josimar N., Alves, Bruno J.R., Boddey, Robert M., and Urquiaga, Segundo
- Subjects
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NITROUS oxide , *CORN , *NO-tillage , *OXISOLS , *AMMONIUM sulfate , *CERRADOS - Abstract
The low natural fertility of Oxisols in the Cerrado region makes some crops in this region very dependent on high rates of synthetic N-fertilizers, which are of growing environmental concern as a major source of N 2 O emissions in agriculture. In a field experiment, we quantified direct N 2 O emissions and NH 3 volatilization (a source of indirect N 2 O emissions) from surface-applied N fertilizer on a no-till maize ( Zea mays L.) crop in Cerrado biome. We used four fertilizers at the rate of 120 kg N ha −1 as topdress-N (V4–V6 growth stage), which were regular urea, urea + zeolite, calcium nitrate and ammonium sulfate, and a non-topdressed control. The total N losses as volatilized NH 3 ranged from 2.2% (calcium nitrate) to 4.5% (urea + zeolite). The N loss as volatilized NH 3 from urea was very low (3.2%), with no significant difference between urea + zeolite, ammonium sulfate and calcium nitrate. Significantly, higher cumulated N 2 O emissions were observed with ammonium sulfate than with the control. No significant differences among fertilizers were found for emission factor (EF), which was 0.20% on average (0.14–0.26%), indicating that use of IPCC default EF (1.00%) would substantially overestimate N 2 O emission. Free drainage and acidity of Oxisols and occurrence of dry spells, known as ‘ veranicos ’, are characteristics of Cerrado biome that may naturally mitigate N 2 O emissions. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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