Nutrient Cycling in Agroecosystems

, Volume 52, Issue 2, pp 123–130

Emissions of N2O from Scottish agricultural soils, as a function of fertilizer N

Authors

  • Keith A. Smith
  • Iain P. McTaggart
  • Karen E. Dobbie
  • Franz Conen
Article

DOI: 10.1023/A:1009781518738

Cite this article as:
Smith, K.A., McTaggart, I.P., Dobbie, K.E. et al. Nutrient Cycling in Agroecosystems (1998) 52: 123. doi:10.1023/A:1009781518738

Abstract

Potato fields and cut (ungrazed) grassland in SE Scotland gave greater annual N2O emissions per ha (1.0–3.2 kg N2O–N ha-1) than spring barley or winter wheat fields (0.3–0.8 kg N2O–N ha-1), but in terms of emission per unit of N applied the order was potatoes > barley > grass > wheat. On the arable land, especially the potato fields, a large part of the emissions occurred after harvest.

When the grassland data were combined with those for 2 years' earlier work at the same site, the mean emission over 3 years, for fertilization with ammonium nitrate, was 2.24 kg N2O–N ha-1 (0.62% of the N applied). Also, a very strong relationship between N2O emission and soil nitrate content was found for the grassland, provided the water-filled pore space was > 70%. Significant relationships were also found between the emissions from potato fields and the soil mineral N content, with the added feature that the emission per unit of soil mineral N was an order of magnitude larger after harvest than before, possibly due to the effect of labile organic residues on denitrification.

Generally the emissions measured were lower, as a function of the N applied, than those used as the basis for the current value adopted by IPCC, possibly because spring/early summer temperatures in SE Scotland are lower than those where the other data were obtained. The role of other factors contributing to emissions, e.g. winter freeze–thaw events and green manure inputs, are discussed, together with the possible implications of future increases in nitrogen fertilizer use in the tropics.

arable cropsglobal warminggrasslandnitrogen fertilizernitrous oxidesoils

Copyright information

© Kluwer Academic Publishers 1998