Bibliografiska uppgifter för Reduced tillage practice is able to reduce CO2 and N2O emissions in a Danish field experiment on sandy loam

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1 Bibliografiska uppgifter för Reduced tillage practice is able to reduce CO2 and N2O emissions in a Danish field experiment on sandy loam Författare Chatskikh D.V., Olesen J.E., Hansen E.M., Elsgaard L. Utgivningsår 26 Tidskrift/serie NJF Report Nr/avsnitt 4 Ingår i... Utgivare Huvudspråk Målgrupp NJF-Seminar 378. system for the benefit of agriculture and the environment Nordiska jordbruksforskares förening (NJF) Engelska Forskare Nummer (ISBN, ISSN) ISSN Denna skrift (rapport, artikel, examensarbete etc.) är hämtad från VäxtEko, databasen som samlar fulltexter om ekologisk odling, växtskydd och växtnäring. Utgivaren har upphovsrätten till verket och svarar för innehållet.

2 Back to Contents Reduced tillage practice is able to reduce CO 2 and O emissions in a Danish field experiment on sandy loam Dmitri Chatskikh a, Jørgen E. Olesen, a Elly M. Hansen a, Lars Elsgaard a a Danish Institute of Agricultural Sciences, Department of Agroecology, P.O. Box 5, DK-883 Tjele, Denmark Abstract Reduced tillage practices, which are widely accepted as conservation tillage in North America, Australia and South Africa are less common in Denmark. To encourage conservation tillage in Europe the environmental side-effects of these practices on different soils and climates have to be better documented and quantified (Olesen, ). The environmental effect of reduced soil tillage intensity was studied in an experiment established in the field in 22 in Denmark, Foulum (56.5ºN, 9.57ºE) on a loamy sand soil (9% clay, 4% organic matter) with a mean annual precipitation of 74 mm and a mean temperature of 7.3 C. Three treatments were included, namely conventional tillage (CT) with rotovation to 8-1 cm and ploughing to 2 cm followed by rolling before sowing, reduced tillage () with rotovation to 8-1 cm and direct drilling (). The treatments were represented by 3 m 2 experimental plots in four replicates in a completely randomised block design. The objective of this study was to assess the effects of different soil tillage intensities on the emissions of CO 2 and O from arable cropping systems over the whole vegetation period. Measurements of CO 2 and O emissions by chambers within vegetation periods of spring barley, winter oilseed rape and winter wheat during 23- showed a decreasing CO 2 emission in the order CT>>. Increased soil tillage intensity in and CT increased O emissions compared to for all vegetation periods. For the winter cereals, gave the highest O emissions, but the cumulated emissions of O were much lower for winter oilseed rape and winter wheat compared to spring barley. However, neither soil total C and N, mineral N measured in spring barley after tillage, nor soil microbiological parameters in winter oilseed rape could explain the differences in emissions between the soil tillage treatments on the time scale studied. Hence, the difference in the emissions between the treatments seems to be caused by changes in soil properties. The O emissions from spring cereals may be reduced by increasing efficiency of N uptake in the spring. A high reduction in CO 2 emissions as was observed in this study under less intensive soil tillage could be useful when improving mitigation procedures for the C sequestration task. 1. Introduction Reduced tillage practices are commonly in use as conservation tillage in America, Australia and South Africa. These soil tillage practices are much less common in Europe, and their environmental side-effects on different soils and climates in the short and long term are poorly documented and should be quantified (Olesen, ). The objective of this study was to assess the effects of different soil tillage intensities on the emissions of CO 2 and O from arable cropping systems over the whole vegetation period. The measurements were conducted in a tillage experiment, which is initiated in

3 2. Material and methods A randomised block design of the experiment included three tillage treatments, represented by 3 m 2 experimental plots in four replicates: conventional tillage (CT), i.e., rotary harrowing to 8-1 cm and mouldboard ploughing to 2 cm followed by rolling before sowing; reduced tillage (), i.e., rotary harrowing to 8-1 cm; direct drilling (), i.e., sowing with disk coulters. The measurements were conducted during March to July 24 in spring barley undersown with perennial ryegrass and during 23 to in winter oilseed rape followed by winter wheat in a tillage experiment initiated in autumn 22 at Foulum in Denmark on a loamy sand soil (9% clay, 4% organic matter, ph(cacl 2 ) 6.1), classified as a Typic Hapludult or Anthric Umbrisol. The climatological normals were 74 mm for annual precipitation and for temperature is 7.3 C. Soil surface fluxes of CO 2 and O were measured once a day by dynamic and static chambers, respectively. Correction of emissions for diurnal variation was based on measurements of GHG fluxes four times a day for a period of three days. Supplementary measurements of soil water retention; water content (TDR) and temperature were collected. Soil mineral N and microbiological parameters were also measured. 3. Results and discussion The reduced soil tillage treatments decreased relative cumulated CO 2 emissions calculated for March to May, but effects on O emissions varied. The O emission from CT under spring barley was in accordance with the emission factor used by IPCC (estimated from the observed period of 11 days), but it was 46% higher than from ; for winter wheat the differences in O emissions between soil tillage treatments were not so evident (Figure 1). This may be due to the fewer measurements taken for this experiments. 5 CT spring barley 1/4/4 1/5/4 1/6/4 1/7/4 5 winter wheat CT 12/9/4 26/9/4 1/1/4 24/1/4 27/3/5 1/4/5 24/4/5 8/5/5 Figure 1. Daily O emissions were lower for and than for CT for spring barley; lower fluxes were obtained for winter wheat in all treatments. 22

4 To access the effects of soil tillage on CO 2 and O emissions the measurement period was divided into periods before and after fertilisation; thus we tried to separate effects of the previous tillage and of following on CO 2 and O emissions. A difference in CO 2 and O emissions between treatments occurred even before tillage in spring for spring barley, whereas there were much smaller differences after fertilization, at least between CT and. Neither soil mineral N measured after tillage for spring barley, nor microbiological parameters for winter rape seemed to reflect the differences in CO 2 and O emissions between the treatments. The fluxes of CO 2 and O were correlated (R 2 =.64***), when they were measured at the same dates after fertilisation. For winter rape in 24 the cumulative CO 2 emission (linearly interpolated for the period March to May) was 23 and 3% lower for and, respectively, compared to CT. For winter wheat in the corresponding differences in CO 2 emission were 26 and 37%. In 24 the CO 2 emissions were in average 37% lower for spring barley compared to winter rape and 33 and 35% lower for and, respectively, compared to CT. 4. Conclusions Reduction in tillage intensity is able to reduce both CO 2 and O emissions in the field. As we found no biochemical explanation for the differences in emissions between the treatments on the short-term time scale they probably could be explained by changes in soil properties, including diffusivity. The O emissions from spring cereals may be reduced by increasing efficiency of N uptake in the spring. 5. Acknowledgements We thank Anette Clausen, Lene Juel Nielsen and Henning Hougaard for technical assistance. This work was financially supported by the Danish Ministry of Food, Agriculture and Fisheries under the research program Agriculture from a holistic resource perspective and by the International Research School of Water Resources (FIVA). 6. References Olesen, J.E. (red.). Drivhusgasser fra jordbruget reduktionsmuligheder. DJF rapport Markbrug nr

5 Back to Contents Reduced tillage practice is able to reduce CO 2 and O emissions in a Danish field experiment on sandy loam Dmitri Chatskikh a, Jørgen E. Olesen, a Elly M. Hansen a, Lars Elsgaard a a Danish Institute of Agricultural Sciences, Department of Agroecology, P.O. Box 5, DK-883 Tjele, Denmark Abstract Reduced tillage practices, which are widely accepted as conservation tillage in North America, Australia and South Africa are less common in Denmark. To encourage conservation tillage in Europe the environmental side-effects of these practices on different soils and climates have to be better documented and quantified (Olesen, ). The environmental effect of reduced soil tillage intensity was studied in an experiment established in the field in 22 in Denmark, Foulum (56.5ºN, 9.57ºE) on a loamy sand soil (9% clay, 4% organic matter) with a mean annual precipitation of 74 mm and a mean temperature of 7.3 C. Three treatments were included, namely conventional tillage (CT) with rotovation to 8-1 cm and ploughing to 2 cm followed by rolling before sowing, reduced tillage () with rotovation to 8-1 cm and direct drilling (). The treatments were represented by 3 m 2 experimental plots in four replicates in a completely randomised block design. The objective of this study was to assess the effects of different soil tillage intensities on the emissions of CO 2 and O from arable cropping systems over the whole vegetation period. Measurements of CO 2 and O emissions by chambers within vegetation periods of spring barley, winter oilseed rape and winter wheat during 23- showed a decreasing CO 2 emission in the order CT>>. Increased soil tillage intensity in and CT increased O emissions compared to for all vegetation periods. For the winter cereals, gave the highest O emissions, but the cumulated emissions of O were much lower for winter oilseed rape and winter wheat compared to spring barley. However, neither soil total C and N, mineral N measured in spring barley after tillage, nor soil microbiological parameters in winter oilseed rape could explain the differences in emissions between the soil tillage treatments on the time scale studied. Hence, the difference in the emissions between the treatments seems to be caused by changes in soil properties. The O emissions from spring cereals may be reduced by increasing efficiency of N uptake in the spring. A high reduction in CO 2 emissions as was observed in this study under less intensive soil tillage could be useful when improving mitigation procedures for the C sequestration task. 1. Introduction Reduced tillage practices are commonly in use as conservation tillage in America, Australia and South Africa. These soil tillage practices are much less common in Europe, and their environmental side-effects on different soils and climates in the short and long term are poorly documented and should be quantified (Olesen, ). The objective of this study was to assess the effects of different soil tillage intensities on the emissions of CO 2 and O from arable cropping systems over the whole vegetation period. The measurements were conducted in a tillage experiment, which is initiated in

6 2. Material and methods A randomised block design of the experiment included three tillage treatments, represented by 3 m 2 experimental plots in four replicates: conventional tillage (CT), i.e., rotary harrowing to 8-1 cm and mouldboard ploughing to 2 cm followed by rolling before sowing; reduced tillage (), i.e., rotary harrowing to 8-1 cm; direct drilling (), i.e., sowing with disk coulters. The measurements were conducted during March to July 24 in spring barley undersown with perennial ryegrass and during 23 to in winter oilseed rape followed by winter wheat in a tillage experiment initiated in autumn 22 at Foulum in Denmark on a loamy sand soil (9% clay, 4% organic matter, ph(cacl 2 ) 6.1), classified as a Typic Hapludult or Anthric Umbrisol. The climatological normals were 74 mm for annual precipitation and for temperature is 7.3 C. Soil surface fluxes of CO 2 and O were measured once a day by dynamic and static chambers, respectively. Correction of emissions for diurnal variation was based on measurements of GHG fluxes four times a day for a period of three days. Supplementary measurements of soil water retention; water content (TDR) and temperature were collected. Soil mineral N and microbiological parameters were also measured. 3. Results and discussion The reduced soil tillage treatments decreased relative cumulated CO 2 emissions calculated for March to May, but effects on O emissions varied. The O emission from CT under spring barley was in accordance with the emission factor used by IPCC (estimated from the observed period of 11 days), but it was 46% higher than from ; for winter wheat the differences in O emissions between soil tillage treatments were not so evident (Figure 1). This may be due to the fewer measurements taken for this experiments. 5 CT spring barley 1/4/4 1/5/4 1/6/4 1/7/4 5 winter wheat CT 12/9/4 26/9/4 1/1/4 24/1/4 27/3/5 1/4/5 24/4/5 8/5/5 Figure 1. Daily O emissions were lower for and than for CT for spring barley; lower fluxes were obtained for winter wheat in all treatments. 22

7 To access the effects of soil tillage on CO 2 and O emissions the measurement period was divided into periods before and after fertilisation; thus we tried to separate effects of the previous tillage and of following on CO 2 and O emissions. A difference in CO 2 and O emissions between treatments occurred even before tillage in spring for spring barley, whereas there were much smaller differences after fertilization, at least between CT and. Neither soil mineral N measured after tillage for spring barley, nor microbiological parameters for winter rape seemed to reflect the differences in CO 2 and O emissions between the treatments. The fluxes of CO 2 and O were correlated (R 2 =.64***), when they were measured at the same dates after fertilisation. For winter rape in 24 the cumulative CO 2 emission (linearly interpolated for the period March to May) was 23 and 3% lower for and, respectively, compared to CT. For winter wheat in the corresponding differences in CO 2 emission were 26 and 37%. In 24 the CO 2 emissions were in average 37% lower for spring barley compared to winter rape and 33 and 35% lower for and, respectively, compared to CT. 4. Conclusions Reduction in tillage intensity is able to reduce both CO 2 and O emissions in the field. As we found no biochemical explanation for the differences in emissions between the treatments on the short-term time scale they probably could be explained by changes in soil properties, including diffusivity. The O emissions from spring cereals may be reduced by increasing efficiency of N uptake in the spring. 5. Acknowledgements We thank Anette Clausen, Lene Juel Nielsen and Henning Hougaard for technical assistance. This work was financially supported by the Danish Ministry of Food, Agriculture and Fisheries under the research program Agriculture from a holistic resource perspective and by the International Research School of Water Resources (FIVA). 6. References Olesen, J.E. (red.). Drivhusgasser fra jordbruget reduktionsmuligheder. DJF rapport Markbrug nr