The effect of organic and conventional cropping systems on CO2 emission from agricultural soils: preliminary results

The effects of different agricultural systems on soil organic carbon content and CO2 emission are investigated in this work. In a long-term experiment a conventional system, characterized by traditional agricultural practices (as deep tillage and chemical input) was compared with an organic one, including minimum tillage, green manure and organic fertilizers. Both systems have a three-year crop rotation including pea – durum wheat – tomato; the organic system is implemented with the introduction of common vetch (Vicia sativa L.) and sorghum (Sorghum vulgare bicolor) as cover crops. In the year 2006 (5 years after the experimentation beginning) was determined the soil C content and was measured the CO2 emissions from soil. The first results showed a trend of CO2 production higher in organic soils in comparison with conventional one. Among the two compared cropping systems the higher differences of CO2 emission were observed in tomato soil respect to the durum wheat and pea soils, probably due to the vetch green manuring before the tomato transplanting. These results are in agreement with the total organic carbon content and water soluble carbon (WSC), which showed the highest values in organic soil. The first observations suggest a higher biological activity and CO2 emission in organic soil than conventional one, likely due to a higher total carbon soil content