Over the entire observation period, the GHG budget was dominated by the net carbon storage change (sequestration or loss). Although the different management led to a systematic difference between the two paired fields, it had only little influence on the inter-annual variation of the carbon budget apart from the renovation effect. The inter-annual variation showed a positive correlation with the net ecosystem productivity and the harvest yield. They were mainly weather driven with influences of the spring temperature and the length of the growing season as well as of the soil moisture content during summer.
While the extensive mostly showed a net carbon loss and a negligibly small N2O exchange, the intensive field showed a continuous carbon sequestration in the six years before the renovation that was counterbalanced to a minor part by N2O emissions. Contrastingly, following the renovation the carbon budget changed its sign from sequestration to loss. This was partly due to respiration losses during the fallow phase between ploughing and reseeding, but smaller carbon losses persisted for about two years. In addition, the N2O emission was also considerably enhanced (about threefold) after the renovation. Overall, management induced differences in the annual GHG budgets of the two paired fields exceeded the weather induced inter-annual variability, especially when considering the strong renovation effect of the intensively managed field.