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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. - PowerPoint PPT Presentation
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Effect of soil compaction and fertilization practise on N2O emission and CH4 oxidation
Sissel Hansen1
Marina A. Bleken2, Bishal K. Sitaula3,
1) Bioforsk Organic Food and Farming Division2) Norwegian Univ. of Life Sciences, Dept. of Plant & Env. Sci.3) Norwegian Univ. of Life Sciences, Dept. of Int. Env. & Dev. Stu.
Outline
•Description of Agriculture in the regionField experiment
•Results N2O emission
N2O of total N and mineral N applied
CH4 uptake
GWP: N2O versus CH4
•Conclusions
Precipitation in mm
0
20
40
60
80
100
120
140
160
180
May June July August September
Average temperatures in °C
0
2
4
6
8
10
12
14
May June July August September
The soil was a well-drained sandy loam soil; the topsoil contained 2.2 % C and 0.17% N
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).
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)
020406080
100120140160180200
7 9
NPK CSH-min N CSH-tot N CSO-min N CSO-tot N
kg N per ha
YearGreen fodder Grassland
Soil compaction treatment:
5 passes each year with a 4 tonne tractor wheel by wheel
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
Effect of soil compaction on N2O consentration in soil air (NH4NO3
fertilized green fodder)
140 kg N ha-1 NH4NO3
Compacted
Uncompacted
Accumulated N2O emission early summer in green fodder year 7; fertilization with NH4NO3 (NPK), cattle slurry high (CSH) and cattle slurry organic (CSO)
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
NPK CSH CSO Unfertilized
kg N
2O
-N h
a-1 Uncompacted
Compacted
Likely reasons for lower N2O emissions from cattle slurry in compacted than in uncompacted soil
N2
N2O
NO
0 30Days
Ratio of NO, N2O and N2 by
denitrifikasjon in silty sand
More nitrogen lost with ammonia volatilization
Alexander,M.1977. Introduction to soil microbiology
Dense soil increases anaerobic microsites and more N is denitrified to N2
Accumulated N2O emission after fertilization with NH4NO3 (NPK), cattle slurry high (CSH) and cattle slurry organic (CSO)
Green fodder, Year 7, early summer
0.0
1.02.0
3.0
4.0
5.06.0
7.0
8.0
NPK CSH CSO Unfertilized
kg N
2O
-N h
a-1 Uncompacted
Compacted
Grassland, Year 9, early summer
0
1
2
3
4
5
6
7
8
NPK CSH CSO Unfertilized
kg
N2O
-N h
a-1
Grassland, Year 9, late summer
0
1
2
3
4
5
6
7
8
NPK CSH CSO Unfertilized
kg N
2O
-N h
a-1
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)
N2O emissions during early summer in % of N added after fertilization with NH4NO3 (NPK), cattle slurry high (CSH) and cattle slurry organic (CSO)
00.5
11.5
22.5
33.5
44.5
5
Year 7 Year 9
NPK CSH-min N CSH-tot N CSO-minN CSO-tot N
00.5
11.5
22.5
33.5
44.5
5
Year 7 Year 9
Uncompacted soil Compacted soil
Accumulated CH4 uptake early summer year 7 and 9 after fertilization with NH4NO3 (NPK), cattle slurry high (CSH) and cattle slurry organic (CSO)
Grassland Year 9, early summer
0102030405060708090
100
NPK CSH CSO Unfertilized
g C
H4 h
a-1
Gren fodder Year 7, early summer
0102030405060708090100
NPK CSH CSO Unfertilized
g C
H4 h
a-1
Uncompacted
Compacted
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
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.
Thank you for your attention
Fertilization with mineral-N (min N) and total N (tot N) in NH4NO3 (NPK), cattle slurry high (CSH) and cattle slurry organic (CSO)
0
50
100
150
200
250
7 8 9 10
NPK CSH-min N CSH-tot N CSO-min N CSO-tot N
kg N per ha
Year Green fodder Barley GrasslandGrassland
N2O emissions during early summer in % of N added with NH4NO3
0
1
2
3
4
5
6
Gren fodder, Year 7 Grassland, Year 9
UncompactedCompacted
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