Soil carbon dioxide emission flux from organic and conventional farming in a long term experiment in Tuscany

Soil microbial biomass represents a significant factor for the evaluation of soil fertility. In the present study we evaluated the development of the soil microbial biomass and soil CO2 emissions in two different agricultural systems: organic and conventional farming on sunflower. Organic farming ensures a higher development of soil microbial community than conventional farming (average 29.1 and 22.5 kg DNA ha-1 , respectively). CO2 emissions proves that soil microbial community in organic farming is more active than conventional (1932.7 and 462.9 kg CO 2 ha-1 , respectively). This is also confirmed by the analysis of qCO2 where organic farming showed approximately three times higher qCO2 than conventional farming (66.3 and 20.5, respectively). However, crop yields highlighted as conventional farming is still more productive than organic farming. This is mainly due to the reduced amount of N that a mix of green manure (legumes and cereals) provide to the successive crop.