Do combined applications of crop residues and inorganic fertilizer lower emission of N2O from soil?

K. A. Frimpong, E. M. Baggs*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Emissions of N2O were measured following addition of 15N-labelled residues of tropical plant species [Vigna unguiculata (cowpea), Mucuna pruriens and Leucaena leucocephala] to a Ferric Luvisol from Ghana at a rate of 100-mg-N/kg soil under controlled environment conditions. Residues were also applied in different ratio combinations with inorganic N fertilizer, at a total rate of 100-mg-N/kg soil. N2O emissions were increased after addition of residues, and further increased with combined (ratio) applications of residues and inorganic N fertilizer. However, 15N-N2O production was low and short-lived in all treatments, suggesting that most of the measured N2O-N was derived from the applied fertilizer or native soil mineral N pools. There was no consistent trend in magnitude of emissions with increasing proportion of inorganic fertilizer in the application. The positive interactive effect between residue- and fertilizer-N sources was most pronounced in the 25:75 Leucaena:fertilizer and cowpea:fertilizer treatments where 1082 and 1130-mg N2O-N/g-residue were emitted over 30-days. N2O (loge) emission from all residue amended treatments was positively correlated with the residue C:N ratio, and negatively correlated with residue polyphenol content, polyphenol:N ratio and (lignin-+-polyphenol):N ratio, indicating the role of residue chemical composition in regulating emissions even when combined with inorganic fertilizer. The positive interactive effect in our treatments suggests that it is unlikely that combined applications of residues and inorganic fertilizer can lower N2O emissions unless the residue is of very low quality promoting strong immobilisation of soil mineral N.

Original languageEnglish
Pages (from-to)412-424
Number of pages13
JournalSoil Use and Management
Volume26
Issue number4
DOIs
Publication statusPublished - 1 Dec 2010

Keywords

  • Crop residues
  • Inorganic fertilizer
  • Nitrous oxide
  • Residue quality
  • Stable isotopes
  • Tropical soil

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