• Authors:
    • Smith, J. U.
    • Glendining, M. J.
    • Powlson, D. S.
    • Smith, P.
  • Source: Global Change Biology
  • Volume: 4
  • Issue: 6
  • Year: 1998
  • Summary: In this paper we estimate the European potential for carbon mitigation of no-till farming using results from European tillage experiments. Our calculations suggest some potential in terms of (a) reduced agricultural fossil fuel emissions, and (b) increased soil carbon sequestration. We estimate that 100% conversion to no-till farming would be likely to sequester about 23 Tg C y-1 in the European Union or about 43 Tg C y-1 in the wider Europe (excluding the former Soviet Union). In addition, up to 3.2 Tg C y-1 could be saved in agricultural fossil fuel emissions. Compared to estimates of the potential for carbon sequestration of other carbon mitigation options, no-till agriculture shows nearly twice the potential of scenarios whereby soils are amended with organic materials. Our calculations suggest that 100% conversion to no-till agriculture in Europe could mitigate all fossil fuel-carbon emissions from agriculture in Europe. However, this is equivalent to only about 4.1% of total anthropogenic CO2-carbon produced annually in Europe (excluding the former Soviet Union) which in turn is equivalent to about 0.8% of global annual anthropogenic CO2-carbon emissions.
  • Authors:
    • Pfadenhauer, J.
    • Klemisch, M.
    • Wild, U.
  • Source: European Journal of Soil Science
  • Volume: 49
  • Issue: 2
  • Year: 1998
  • Summary: Trace gas fluxes of N2O and CH4 were measured weekly over 12 months on cultivated peaty soils in southern Germany using a closed chamber technique. The aim was to quantify the effects of management intensity and of soil and climatic factors on the seasonal variation and the total annual exchange rates of these gases between the soil and the atmosphere. The four experimental sites had been drained for many decades and used as meadows (fertilized and unfertilized) and arable land (fertilized and unfertilized), respectively. Total annual N2O-N losses amounted to 4.2, 15.6, 19.8 and 56.4 kg ha(-1) year(-1) for the fertilized meadow, the fertilized field, the unfertilized meadow and the unfertilized field, respectively. Emission of N2O occurred mainly in the winter when the groundwater level was high. At all sites maximum emission rates were induced by frost. The largest annual N2O emission by far occurred from the unfertilized field where the soil pH was low (4.0). At this site 71% of the seasonal variation of N2O emission rates could be explained by changes in the groundwater level and soil nitrate content. A significant relationship between N2O emission rates and these factors was also obtained for the other sites, which had a soil pH between 5.1 and 5.8, though the relation was weak (R-2 = 15-27%). All sites were net sinks for atmospheric methane. Up to 78% of the seasonal variation in CH4 flux rates could be explained by changes in the groundwater level. The total annual CH4-C uptake was significantly affected by agricultural land use with greater CH4 consumption occurring on the meadows (1043 and 833 g ha(-1)) and less on the cultivated fields (209 and 213 g ha(-1)).
  • Authors:
    • Parton, W. J.
    • Mueller, T.
    • Molina, J. A. E.
    • Li, C.
    • Komarov, A. S.
    • Klein-Gunnewiek, H.
    • Kelly, R. H.
    • Jensen, L. S.
    • Jenkinson, D. S.
    • Frolking, S.
    • Franko, U.
    • Coleman, K.
    • Chertov, O. G.
    • Arah, J. R. M.
    • McGill, W. B.
    • Powlson, D. S.
    • Smith, J. U.
    • Smith, P.
    • Thornley, J. H. M.
    • Whitmore, A. P.
  • Source: Geoderma
  • Volume: 81
  • Issue: 1-2
  • Year: 1997
  • Summary: Nine soil organic models were evaluated using twelve datasets from seven long-term experiments. Datasets represented three different land-uses (grassland, arable cropping and woodland) and a range of climatic conditions within the temperate region. Different treatments (inorganic fertilizer, organic manures and different rotations) at the same site allowed the effects of differing land management to be explored. Model simulations were evaluated against the measured data and the performance of the models was compared both qualitatively and quantitatively. Not all models were able to simulate all datasets; only four attempted all. No one model performed better than all others across all datasets. The performance of each model in simulating each dataset is discussed. A comparison of the overall performance of models across all datasets reveals that the model errors of one group of models (RothC, CANDY, DNDC, CENTURY, DAISY and NCSOIL) did not differ significantly from each other. Another group (SOMM, ITE and Verberne) did not differ significantly from each other but showed significantly larger model errors than did models in the first group. Possible reasons for differences in model performance are discussed in detail.