Modelling of nitrous oxide emissions from clover grass ley : wheat crop rotations in central eastern Germany : an application of DNDC
(2014) In Student thesis series INES NGEM01 20132Dept of Physical Geography and Ecosystem Science
- Abstract
- Nitrous oxide (N2O) is one of the three primary anthropogenic greenhouse gases. The agricultural sector accounts for 75.7 % of all anthropogenic N2O emissions in Germany (Umweltbundesamt, 2012). Thus, accurately estimating N2O emissions as well as mitigation strategies for N2O are crucial.
This study optimizes the process-based model DNDC to simulate N2O emissions by conventional winter wheat and three different organic clover grass ley – wheat rotations at a site in central eastern Germany (Bad Lauchstädt: 51°24' N, 11°53' E ). The model simulates the soil environment (temperature, moisture, oxygen content etc.), plant growth and decomposition to determine nitrification, denitrification as well as fermentation. The central focus of this... (More) - Nitrous oxide (N2O) is one of the three primary anthropogenic greenhouse gases. The agricultural sector accounts for 75.7 % of all anthropogenic N2O emissions in Germany (Umweltbundesamt, 2012). Thus, accurately estimating N2O emissions as well as mitigation strategies for N2O are crucial.
This study optimizes the process-based model DNDC to simulate N2O emissions by conventional winter wheat and three different organic clover grass ley – wheat rotations at a site in central eastern Germany (Bad Lauchstädt: 51°24' N, 11°53' E ). The model simulates the soil environment (temperature, moisture, oxygen content etc.), plant growth and decomposition to determine nitrification, denitrification as well as fermentation. The central focus of this study is to assess the ability of DNDC to simulate N2O emissions in Bad Lauchstädt, followed by a comparison of the different crop rotations with respect to their N2O emissions based on weekly measurements and DNDC simulations. The study concludes with an investigation of emissions under future climate conditions.
DNDC is able to reproduce monthly patterns of emissions in Bad Lauchstädt. Underlying processes such as plant growth and soil moisture are not represented with sufficient precision. The mean modelling efficiency (Nash Sutcliff Efficiency) of the validation runs for the monthly N2O fluxes is 0.136 and ranges from -0.526 to 0.446. Predicted daily and annual fluxes show a great offset compared to measured values. Emissions in Bad Lauchstädt are very low if compared to other observations in Germany and are primarily constrained by soil moisture and not by nitrogen availability. Neither the measurements nor the modelling results are able to resolve significant differences between the four crop rotations. According to the measurements, conventional winter wheat emits 836 g N ha-1 a-1, while the organic treatments release between 645 g N ha-1 a-1 and 1044 g N ha-1 a-1. DNDC simulates no significant change of N2O emissions under future climate conditions; this finding is not robust due to the abovementioned drawbacks of DNDC in this study.
Improved estimates could be obtained by adjusting the ability of DNDC to capture the situation in Germany and in Bad Lauchstädt. Special attention should be given to the implementation of plant growth and evapotranspiration. Better comparison of treatments requires a longer measurement period and a higher temporal resolution, so that duration and height of peak emission events can be captured. (Less) - Popular Abstract
- In the media climate change is often linked to high emissions of carbon dioxide produced by industrial plants, plains or cars. However, the agricultural sector contributes significantly to the change of climate by emitting next to carbon dioxide also nitrous oxide. This has a 300 times greater effect on climate compared to carbon dioxide. Therefore, it is particularly important to reduce emissions of nitrous oxide and estimate emissions accurately.
This study compares typical winter wheat crop rotations in organic and conventional farming in Bad Lauchstädt, central eastern Germany, based on measurements and the computer model DNDC. Organic and conventional farming differ with respect to fertilizer application, manure amendment and tilling... (More) - In the media climate change is often linked to high emissions of carbon dioxide produced by industrial plants, plains or cars. However, the agricultural sector contributes significantly to the change of climate by emitting next to carbon dioxide also nitrous oxide. This has a 300 times greater effect on climate compared to carbon dioxide. Therefore, it is particularly important to reduce emissions of nitrous oxide and estimate emissions accurately.
This study compares typical winter wheat crop rotations in organic and conventional farming in Bad Lauchstädt, central eastern Germany, based on measurements and the computer model DNDC. Organic and conventional farming differ with respect to fertilizer application, manure amendment and tilling practice and thus by the availability of nitrogen in the soil to form nitrous oxide. The main aim was to test the capability of the computer model to simulate emissions. Furthermore, this report compares different crop rotations and investigates emissions under future climate conditions.
Overall the model showed a good performance when simulating monthly emissions, but had a great offset when compared to daily or annual observations. The central weakness of DNDC was its disability to simulate some of the main factors that control nitrous oxide emissions, such as soil moisture, plant growth and soil organic carbon. This study did not reveal differences between various organic and conventional farming practices. Nitrous oxide emissions in Bad Lauchstädt are mostly constrained by low precipitation and thus soil moisture, but not by the availability of nitrogen. The computer model does not show higher nitrous oxide emissions under future climate conditions. Due to drawbacks in DNDC this result is not reliable.
Better simulations and comparison could be achieved in several ways. The computer model was built to be applicable all-around the globe. However, this adds great uncertainty. DNDC could be improved by adjusting some parts of it as the plant growth to better fit the conditions
in Germany. More profound comparison of crop rotations could be attained by long-term series of measurements with a higher spatial and temporal resolution. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/4694345
- author
- Kayatz, Benjamin LU
- supervisor
- organization
- course
- NGEM01 20132
- year
- 2014
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- clover grass ley, Bad Lauchstädt, N2O, ecosystem analysis, physical Geography, DNDC, winter wheat, spring wheat, climate change, emission factors
- publication/series
- Student thesis series INES
- report number
- 325
- language
- English
- additional info
- External supervisor: Dr. Rene Dechow, Institute of Climate-Smart Agriculture, Johann Heinrich von Thünen-Institute, Brunswick, Germany
- id
- 4694345
- date added to LUP
- 2014-10-06 12:29:10
- date last changed
- 2015-04-30 03:58:08
@misc{4694345,
abstract = {{Nitrous oxide (N2O) is one of the three primary anthropogenic greenhouse gases. The agricultural sector accounts for 75.7 % of all anthropogenic N2O emissions in Germany (Umweltbundesamt, 2012). Thus, accurately estimating N2O emissions as well as mitigation strategies for N2O are crucial.
This study optimizes the process-based model DNDC to simulate N2O emissions by conventional winter wheat and three different organic clover grass ley – wheat rotations at a site in central eastern Germany (Bad Lauchstädt: 51°24' N, 11°53' E ). The model simulates the soil environment (temperature, moisture, oxygen content etc.), plant growth and decomposition to determine nitrification, denitrification as well as fermentation. The central focus of this study is to assess the ability of DNDC to simulate N2O emissions in Bad Lauchstädt, followed by a comparison of the different crop rotations with respect to their N2O emissions based on weekly measurements and DNDC simulations. The study concludes with an investigation of emissions under future climate conditions.
DNDC is able to reproduce monthly patterns of emissions in Bad Lauchstädt. Underlying processes such as plant growth and soil moisture are not represented with sufficient precision. The mean modelling efficiency (Nash Sutcliff Efficiency) of the validation runs for the monthly N2O fluxes is 0.136 and ranges from -0.526 to 0.446. Predicted daily and annual fluxes show a great offset compared to measured values. Emissions in Bad Lauchstädt are very low if compared to other observations in Germany and are primarily constrained by soil moisture and not by nitrogen availability. Neither the measurements nor the modelling results are able to resolve significant differences between the four crop rotations. According to the measurements, conventional winter wheat emits 836 g N ha-1 a-1, while the organic treatments release between 645 g N ha-1 a-1 and 1044 g N ha-1 a-1. DNDC simulates no significant change of N2O emissions under future climate conditions; this finding is not robust due to the abovementioned drawbacks of DNDC in this study.
Improved estimates could be obtained by adjusting the ability of DNDC to capture the situation in Germany and in Bad Lauchstädt. Special attention should be given to the implementation of plant growth and evapotranspiration. Better comparison of treatments requires a longer measurement period and a higher temporal resolution, so that duration and height of peak emission events can be captured.}},
author = {{Kayatz, Benjamin}},
language = {{eng}},
note = {{Student Paper}},
series = {{Student thesis series INES}},
title = {{Modelling of nitrous oxide emissions from clover grass ley : wheat crop rotations in central eastern Germany : an application of DNDC}},
year = {{2014}},
}