Efficient ways of reducing greenhouse gas emissions from agriculture

Agriculture can use a range of measures to reduce greenhouse gas emissions. A new report provides an overview of the potentials, effects and barriers of these measures.

2018.09.27 | Janne Hansen

One of the measures that can be used to reduce agricultural greenhouse emissions is to set aside and re-wet organic soils. Photo: Foto: Janne Hansen

Agriculture contributes about 20 percent of the total Danish greenhouse gas emissions when measured in terms of their global warming potentials. It is, however, possible to reduce the emissions, as shown in a new report from DCA – Danish Centre for Food and Agriculture at Aarhus University.

The report provides an overview of the potentials, effects and barriers for various measures for reducing the emission of greenhouses gases from agriculture up to 2030. The measures mentioned in the report vary significantly with regard to their effects, side effects and cost efficiency, but there are five measures that the authors of the report have singled out as being promising. These measures are:  

  1. Altered feeding of cattle and young stock with concentrate, fat and easily digestible forage
  2. Biogas, with or without frequent emptying of slurry from house to storage or cooling of slurry in the livestock house
  3. Acidification of slurry in the livestock house
  4. Addition of nitrification inhibitors to mineral fertilisers and animal manure (slurry)
  5. Set-aside of organic soils with or without re-wetting of the land 

- The measures mentioned and their effects on greenhouse gas emissions reflect a realistic estimate of how widespread the selected measures may be implemented, and the evaluations are based on current frameworks for agricultural production, says one of the authors of the report, Section Manager and Professor Jørgen E. Olesen from the Department of Agroecology at Aarhus University. 

In connection with the project, the Department of Food and Resource Economics at the University of Copenhagen has estimated the costs of the selected measures in a separate report.   

Measures must be efficient and economic

Selection of the most promising measures was based on a range of criteria, including effect and cost efficiency. In order for a measure to be relevant, it must fulfill the following criteria:  

  • have a significant effect on total emissions
  • be well documented so that it can be integrated in the national inventory
  • be economically competitive
  • be suitable for implementation with no significant negative side effects
  • be possible to include in the national emission inventory through available data on implementation rate 

The effects of the measures are calculated for each measure on its own without taking possible interactions with other effects into account. The values for greenhouse gas emission reduction presented in the report are therefore not necessarily additive. However, to account for measures regarding treatment of animal manure (slurry), it has been taken into consideration that the measures must not overshadow each other. Some of the measures are additive, while others will have such overshadowing effects. With regard to the other measures, the effects have been calculated with and without carbon storage in the soil and vegetation. Energy consumption and substitution of fossil energy (from biogas) in the transportation sector have also been included in the calculations for several of the measures.  

- Some of the measures could immediately be included in the national emission inventory. This is the case for altered feeding, biogas and set-aside of organic soils. With regard to slurry acidification and addition of nitrification inhibitors, there is a need for further documentation of the effects under practical conditions, before they can be included in the emission inventory. With regard to nitrification inhibitors, side effects, such as leaching of these chemicals to the groundwater, must also be considered, before applying the measures on a large scale, says Jørgen E. Olesen.   

Set-aside and rewetting of organic soils would have the absolutely greatest effect with a potential reduction of 1.35 million tons CO2 equivalents in 2030. If all five measures were applied, their total potential effect would be a reduction of 1.70-2.75 million tons COequivalents in 2030. 

Other possibilities for reducing greenhouse gases

In many situations, there is interaction between the various measures for reducing emissions. Analyses carried out for the report have not taken these interactions into consideration. This would require a farm-oriented analysis rather than analyses of the individual measures. The effects would thus depend on the crop rotations as well as manure management and related technologies for reducing emissions. 

It is also possible to affect agricultural greenhouse gas emissions by changing production systems. Precision agriculture, conservation agriculture and organic farming are possible ways of reducing emissions. With regard to all these production systems, it is difficult to calculate emission reductions accurately, because changes in production systems involve changes in flows of nitrogen and carbon and in the cultivation system, which in turn affect greenhouse gas emissions, but which are difficult to quantify.  

Pressing need for more knowledge

Identification of five particularly effective measures for reducing agricultural greenhouse gas emissions does not mean that the goals for reducing emissions are met. Much more knowledge is needed to achieve additional emissions reductions.  

- There is a great need for research in reducing agricultural greenhouse gas emissions. This is the case for both new technologies and management systems with lower emissions, and with regard to improved quantification of actual emissions and documentation of effects of currently available measures, Jørgen E. Olesen points out. 


The report was produced in collaboration between the Department of Agroecology at Aarhus University and the Department of Food and Resource Economics at the University of Copenhagen at the request of the Ministry of Environment and Food of Denmark.  

 

For more information please contact
Section manager, Professor Jørgen E. Olesen,
Department of Agroecology, Aarhus University
Email: jeo@agro.au.dk
Telephone: +45 8715 7778
mobile: +45 4082 1659

Agro, DCA