Reduction of amount CO2 is possible by carbon sequestration to the soil. Fixation potential of EU–15 agricultural land is c. 16–19 mil t C . year−1. Amount and composition of post–harvest residues is essential for carbon soil sequestration. Long–term yield series of the most planted crops (winter wheat – Triticum aestivum, spring barley – Hordeum vulgare, corn and silage maize – Zea mays, winter rape – Brassica napus, potatoes – Solanum tuberosum, sugar beet – Beta vulgaris, alfalfa – Medicago sativa, red clover – Trifolium pratense, white mustard – Sinapis alba and fiddleneck – Phacelia tanacetifolia) in various agroecological conditions and growing technologies were used for carbon balance calculation. The carbon balances were calculated for main crop rotations of maize, sugar beet, cereal and potato production regions (24 crop rotations). The calculations were realized for following planting varieties: traditional, commercial, ecological and with higher rate of winter rape. All chosen crop rotations (except seven) have positive carbon balance in the tillage system. Amount of fixed carbon might be increases about 30% by the use of no–tillage system. Least amount of carbon is fixed by potatoes, high amount by cereals, alfalfa and sugar beet. For a short time (months) the crops sequestration of carbon is relatively high (to 4.4 t . ha−1 . year−1) or to 5.7 t . ha−1 . year−1 for no–tillage system. From the long time viewpoint (tens of years) the data of humified carbon in arable soil (max 400 kg C . ha−1 . year−1) are important. Maximal carbon deficit of chosen crop rotation is 725 kg C . year−1.
Carbon sequestration in clay and silt fractions of Brazilian soils under conventional and no-tillage systems