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Effect of soil compaction and fertilization practise on N 2 O emission and CH 4 oxidation

Effect of soil compaction and fertilization practise on N 2 O emission and CH 4 oxidation. Sissel Hansen 1 Marina A. Bleken 2 , Bishal K. Sitaula 3 , Bioforsk Organic Food and Farming Division Norwegian Univ. of Life Sciences, Dept. of Plant & Env. Sci.

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Effect of soil compaction and fertilization practise on N 2 O emission and CH 4 oxidation

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  1. Effect of soil compaction and fertilization practise on N2O emission and CH4 oxidation Sissel Hansen1 Marina A. Bleken2, Bishal K. Sitaula3, • Bioforsk Organic Food and Farming Division • Norwegian Univ. of Life Sciences, Dept. of Plant & Env. Sci. • Norwegian Univ. of Life Sciences, Dept. of Int. Env. & Dev. Stu.

  2. Outline • Description of • Agriculture in the region • Field experiment • Results • N2O emission • N2O of total N and mineral N applied • CH4 uptake • GWP: N2O versus CH4 • Conclusions

  3. Precipitation in mm

  4. Average temperatures in °C

  5. The soil was a well-drained sandy loam soil; the topsoil contained 2.2 % C and 0.17% N

  6. Field experiment: • 10 years • Crop rotation adapted to organic dairy farming • High frequency of legumes Split-plot factorial design with two replicates, soil compaction on main plots and fertilization on small plots (2.8 m x 8 m).

  7. Nitrogen Input and sources: Fertilization with mineral-N (min N) and total N (tot N) in NH4NO3 (NPK), cattle slurry high (CSH) and cattle slurry organic (CSO) kg N per ha Year Green fodder Grassland

  8. Soil compaction treatment: 5 passes each year with a 4 tonne tractor wheel by wheel

  9. Gas fluxes measured by soil cover chambers Spring year 7 and 9, late summer year 9 Four parallel flux measurements taken on each day of measurement. The flux was estimated by the increased concentration 3 hours after placement

  10. Effect of soil compaction on N2O consentration in soil air (NH4NO3 fertilized green fodder) 140 kg N ha-1 NH4NO3 Compacted Uncompacted

  11. Accumulated N2O emission early summer in green fodder year 7; fertilization with NH4NO3 (NPK), cattle slurry high (CSH) and cattle slurry organic (CSO)

  12. N2 N2O NO 0 30 Likely reasons for lower N2O emissions from cattle slurry in compacted than in uncompacted soil More nitrogen lost with ammonia volatilization Dense soil increases anaerobic microsites and more N is denitrified to N2 Ratio of NO, N2O and N2 bydenitrifikasjon in silty sand Alexander,M.1977. Introduction to soil microbiology Days

  13. Accumulated N2O emission after fertilization with NH4NO3 (NPK), cattle slurry high (CSH) and cattle slurry organic (CSO)

  14. N2O emissions during early summer in % of N added after fertilization with NH4NO3 (NPK), cattle slurry high (CSH) and cattle slurry organic (CSO) The average percentage fertilizer-derived N2O emissions was calculated as the N2O emission in fertilized treatments minus N2O emission in unfertilized treatment, divided by the amount of mineral N (total-N) applied with spring fertilization in year 7 (green fodder) and year 9 (grassland)

  15. N2O emissions during early summer in % of N added after fertilization with NH4NO3 (NPK), cattle slurry high (CSH) and cattle slurry organic (CSO) Uncompacted soil Compacted soil

  16. Accumulated CH4 uptake early summer year 7 and 9 after fertilization with NH4NO3 (NPK), cattle slurry high (CSH) and cattle slurry organic (CSO)

  17. GWP effect of CH4 oxidation versus N2O emission • 720 times more CO2 equivalents were emitted as N2O, than absorbed in soil through CH4 oxidation in CSO treatment • NPK (NH4NO3) treatment 1860 times Calculations: N2O = 310 times CO2, CH4=23 times CO2

  18. Conclusion • Include effects of soil structure and soil moisture when estimates of N2O emissions are maid • Higher N2O emissions per ha from conventional than organic fertilization practise • Soil compaction increased the emissions, particularly after fertilization with NH4NO3 • Soil compaction decreased net CH4 uptake • The effect of methane oxidation on reduced GWP was negligible compared with increased GWP caused by N2O emission.

  19. Thank you for your attention

  20. Fertilization with mineral-N (min N) and total N (tot N) in NH4NO3 (NPK), cattle slurry high (CSH) and cattle slurry organic (CSO) kg N per ha Year Green fodder Barley Grassland Grassland

  21. N2O emissions during early summer in % of N added with NH4NO3

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