@article{Scheer2012b,
title = {Nitrous oxide emissions from irrigated wheat in Australia: Impact of irrigation management},
author = { C Scheer and P. R. Grace and D.W Rowlings and J. Payero},
doi = {10.1007/s11104-012-1197-4},
year = {2012},
date = {2012-03-23},
journal = {Plant & Soil},
volume = {359},
number = {1},
pages = {351-362},
abstract = {"Background and aims
Irrigation management affects soil water dynamics as well as the soil microbial carbon and nitrogen turnover and potentially the biosphere-atmosphere exchange of greenhouse gasses (GHG). We present a study on the effect of three irrigation treatments on the emissions of nitrous oxide (N_{2}O) from irrigated wheat on black vertisols in South-Eastern Queensland, Australia.
Methods
Soil N_{2}O fluxes from wheat were monitored over one season with a fully automated system that measured emissions on a sub-daily basis. Measurements were taken from 3 subplots for each treatment within a randomized split-plot design.
Results Highest N_{2}O emissions occurred after rainfall or irrigation and the amount of irrigation water applied was found to influence the magnitude of these “emission pulses”. Daily N_{2}O emissions varied from −0.74 to 20.46 g N_{2}O-N ha^{−1} day^{−1} resulting in seasonal losses ranging from 0.43 to 0.75 kg N_{2}O-N ha^{−1} season^{ − 1} for the different irrigation treatments. Emission factors (EF = proportion of N fertilizer emitted as N_{2}O) over the wheat cropping season, uncorrected for background emissions, ranged from 0.2 to 0.4 % of total N applied for the different treatments. Highest seasonal N_{2}O emissions were observed in the treatment with the highest irrigation intensity; however, the N_{2}O intensity (N_{2}O emission per crop yield) was highest in the treatment with the lowest irrigation intensity.
Conclusions Our data suggest that timing and amount of irrigation can effectively be used to reduce N_{2}O losses from irrigated agricultural systems; however, in order to develop sustainable mitigation strategies the N_{2}O intensity of a cropping system is an important concept that needs to be taken into account."},
keywords = {Plant and Soil},
pubstate = {published},
tppubtype = {article}
}
"Background and aims
Irrigation management affects soil water dynamics as well as the soil microbial carbon and nitrogen turnover and potentially the biosphere-atmosphere exchange of greenhouse gasses (GHG). We present a study on the effect of three irrigation treatments on the emissions of nitrous oxide (N2O) from irrigated wheat on black vertisols in South-Eastern Queensland, Australia.
Methods
Soil N2O fluxes from wheat were monitored over one season with a fully automated system that measured emissions on a sub-daily basis. Measurements were taken from 3 subplots for each treatment within a randomized split-plot design.
Results Highest N2O emissions occurred after rainfall or irrigation and the amount of irrigation water applied was found to influence the magnitude of these “emission pulses”. Daily N2O emissions varied from −0.74 to 20.46 g N2O-N ha−1 day−1 resulting in seasonal losses ranging from 0.43 to 0.75 kg N2O-N ha−1 season − 1 for the different irrigation treatments. Emission factors (EF = proportion of N fertilizer emitted as N2O) over the wheat cropping season, uncorrected for background emissions, ranged from 0.2 to 0.4 % of total N applied for the different treatments. Highest seasonal N2O emissions were observed in the treatment with the highest irrigation intensity; however, the N2O intensity (N2O emission per crop yield) was highest in the treatment with the lowest irrigation intensity.
Conclusions Our data suggest that timing and amount of irrigation can effectively be used to reduce N2O losses from irrigated agricultural systems; however, in order to develop sustainable mitigation strategies the N2O intensity of a cropping system is an important concept that needs to be taken into account."
@article{Scheer2011,
title = {Effect of biochar amendment on the soil-atmosphere exchange of greenhouse gases from an intensive subtropical pasture in Northern New South Wales, Australia.},
author = { C Scheer and P. R. Grace and D Rowlings and S. Kimber and L van Zwieten},
doi = {10.1007/s11104-011-0759-1},
year = {2011},
date = {2011-03-08},
journal = {Plant & Soil},
volume = {345},
number = {1},
pages = {47-58},
abstract = {We assessed the effect of biochar incorporation into the soil on the soil-atmosphere exchange of the greenhouse gases (GHG) from an intensive subtropical pasture. For this, we measured N_{2}O, CH_{4} and CO_{2} emissions with high temporal resolution from April to June 2009 in an existing factorial experiment where cattle feedlot biochar had been applied at 10 t ha^{−1} in November 2006. Over the whole measurement period, significant emissions of N_{2}O and CO_{2} were observed, whereas a net uptake of CH_{4} was measured. N_{2}O emissions were found to be highly episodic with one major emission pulse (up to 502 μg N_{2}O-N m^{−2} h^{−1}) following heavy rainfall. There was no significant difference in the net flux of GHGs from the biochar amended vs. the control plots. Our results demonstrate that intensively managed subtropical pastures on ferrosols in northern New South Wales of Australia can be a significant source of GHG. Our hypothesis that the application of biochar would lead to a reduction in emissions of GHG from soils was not supported in this field assessment. Additional studies with longer observation periods are needed to clarify the long term effect of biochar amendment on soil microbial processes and the emission of GHGs under field conditions.},
keywords = {Plant and Soil},
pubstate = {published},
tppubtype = {article}
}
We assessed the effect of biochar incorporation into the soil on the soil-atmosphere exchange of the greenhouse gases (GHG) from an intensive subtropical pasture. For this, we measured N2O, CH4 and CO2 emissions with high temporal resolution from April to June 2009 in an existing factorial experiment where cattle feedlot biochar had been applied at 10 t ha−1 in November 2006. Over the whole measurement period, significant emissions of N2O and CO2 were observed, whereas a net uptake of CH4 was measured. N2O emissions were found to be highly episodic with one major emission pulse (up to 502 μg N2O-N m−2 h−1) following heavy rainfall. There was no significant difference in the net flux of GHGs from the biochar amended vs. the control plots. Our results demonstrate that intensively managed subtropical pastures on ferrosols in northern New South Wales of Australia can be a significant source of GHG. Our hypothesis that the application of biochar would lead to a reduction in emissions of GHG from soils was not supported in this field assessment. Additional studies with longer observation periods are needed to clarify the long term effect of biochar amendment on soil microbial processes and the emission of GHGs under field conditions.
