"COMET-Global" project completed

Tool for greenhouse gas accounting at farm-level developped. Composted organic manure and reduced tillage cuts down the net greenhouse gas (GHG) emissions without any loss in yields.

Experimental sites selected for the parameterisation and evaluation of the DayCent model under Swiss conditions.

​Intensive use of agricultural land has led to an unprecedented global loss of 50 Gt (1 Gigatonne = 1,000,000,000 tonnes) of the organic carbon content of the soils in the form of CO2. In 2010, agriculture globally generated GHG emissions of 5.0-5.8 Gt CO2 equivalents, which corresponds to 10-12 per cent of all anthropogenic GHG emissions. Cultivation methods which increase the level of soil organic matter and reduce nutrient loss and GHG emissions are currently highly sought after. In addition, the necessary information must be available to those who decide what to grow - for each individual field. The objective of the COMET-Global project was to develop and implement a web-based, user-friendly, ultramodern tool for the comprehensive GHG accounting of individual units (e.g. field, plant production, mixed farm) for the partner countries, including several EU countries, the USA and Australia.

One of the results consisted in parameterising and evaluating the DayCent model at four sample sites for common crop plants and cultivation systems as well as for soil and climate conditions in Switzerland.

In addition, the project has increased our understanding of the effects of cultivation practices on GHG emissions from the soil in longer periods and across wider spaces. Knowledge gained through the analyses can serve as a guideline for designing future GHG studies und field conditions. The long-term effects of cultivation methods and their combinations on GHG emissions for agricultural soils in Switzerland were also evaluated at various sites and in different regions. While the use of partially composted organic fertilisers substantially reduced net GHG emissions - particularly if the soil was less intensively tilled - it diminished overall production at the same time. By using the fully composted fertilisers and reducing or entirely stopping tillage, however, it was possible to reduce net GHG emissions from the soil without any significant loss in yields (less than 5% lost).

In future, all stakeholders in the individual partner countries are expected to use the COMET-Global tool to fully record GHG at farm level ahead of any changes to land use or cultivation.