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Article Dans Une Revue Soil Research Année : 2019

Urea and legume residues as 15N-N2O sources in a subtropical soil

Résumé

In this work, we used the 15 N labelling technique to identify the sources of N 2 O emitted by a subtropical soil following application of mineral nitrogen (N) fertiliser (urea) and residues of a legume cover crop (cowpea). For this purpose, a 45-day incubation experiment was conducted by subjecting undisturbed soil cores from a subtropical Acrisol to five different treatments: (1) control (no crop residue or fertiliser-N application); (2) 15 N-labelled cowpea residue (200 mg N g-1 soil); (3) 15 N-labelled urea (200 mg N g-1 soil); (4) 15 N-labelled cowpea residue (100 mg N g-1 soil) + unlabelled urea (100 mg N g-1 soil); and (5) unlabelled cowpea residue (100 mg N g-1 soil) + 15 N-labelled urea (100 mg N g-1 soil). Cores were analysed for total N 2 O formation, d 15 N-N 2 O and d 18 ON 2 O by continuous flow isotope ratio mass spectrometry, as well as for total NO 3-N and NH 4 +-N. Legume crop residues and mineral fertiliser increased N 2 O emissions from soil to 10.5 and 9.7 mg N 2 ON cm-2 respectively, which was roughly six times the value for control (1.5 mg N 2 ON cm-2). The amount of 15 N 2 O emitted from labelled 15 N-urea (0.40-0.45% of 15 N applied) was greater than from 15 N-cowpea residues (0.013-0.015% of 15 N applied). Unlike N-poor crop residues, urea in combination with N-rich residues (cowpea) failed to reduce N 2 O emissions relative to urea alone. Legume cover crops thus provide an effective mitigation strategy for N 2 O emissions in relation to mineral N fertilisation in climate-smart agriculture. Judging by our inconclusive results, however, using urea in combination with N-rich residues provides no clear-cut environmental advantage.

Domaines

Science des sols
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Dates et versions

hal-04260806 , version 1 (26-10-2023)

Identifiants

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J Gomes, N Brüggemann, D P Dick, G M Pedroso, Murilo Veloso, et al.. Urea and legume residues as 15N-N2O sources in a subtropical soil. Soil Research, 2019, 57, ⟨10.1071/sr18300⟩. ⟨hal-04260806⟩

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