Carbon Dioxide Emissions From Different Soil Tillage Systems.

One aspect of sustainable agriculture is the use of reduced soil tillage or no-till systems. In comparison to conventional tillage these soil management systems are supposed to cause lower carbon dioxide emissions: On the one hand less intensive or even no soil tillage treatment may result in slower mineralization of soil organic carbon and enhanced carbon sequestration, and on the other hand less machinery usage implies a reduction in fuel combustion and therefore reduced CO2 emissions.

In order to assess the carbon dioxide emissions due to soil respiration and fuel combustion for different tillage systems a study of three years duration is performed. Following three tillage systems are compared: Conventional tillage (CT), reduced tillage (RT), and no-tillage (NT). Field measurements are carried out at five agricultural fields in Austria. The sites differ in climatic conditions, soil texture, slope and crop rotation. All fields are part of long-term tillage treatment experiments performed by agricultural schools. In intervals of one to two weeks soil CO2 efflux is measured using a portable soil respiration system (non-steady-state through-flow). Additionally, concurrent soil temperature and soil water content are measured and soil samples are taken for chemical and microbiological analyses. The CO2 emissions due to fuel combustion are derived from fuel consumption measurements which are performed for several management operations.

The results of the study show a high spatial heterogeneity of soil respiration data even within one plot. Nevertheless, the level of soil CO2 efflux was similar for CT and RT, but usually higher than for NT. For seedbed preparation and planting the fuel consumption measurements show a reduction in CO2 emissions of about 52% for RT and even about 89% for NT in comparison to CT.