Based on a long-term experiment during 1979—2014 with various fertilizations in black soil of northeast China

the objective of this study was to research evolution characteristics of soil organic carbon (SOC) content

carbon sequestration and its cooperation with carbon input. The results showed that: Compared to the initial soil condition

SOC content in long-term chemical fertilizers application (N

NP

NPK

N2) decreased by 11.6%～16.1%

while the SOC content in long-term horse manure application significantly increased. Chemical fertilizers application plus horse manure with conventional application rates (MNP

MNPK) or doubleness (M2N2

M2N2P2) could increase SOC content 6.5%

8.4%

7.7% and 11.6%

respectively. The carbon sequestration in the treatment of non-fertilization (CK) and chemical fertilizers application appeared deficit

ranged from 3.5～6.1 t/hm2. In contrast

SOC storage in the treatment of chemical fertilizers application plus horse manure showed surplus

and the maximum value was 1.9 t/hm2 (M2N2P2). There was a significantly positive linear correlation between annual average organic C input and C sequestration efficiency

which showed that black soil still had potential carbon sequestration. The calculated annual transform rate of input carbon was about 34.1%

and the least carbon input for maintaining the initial organic carbon level was about 1.416 t/hm2. Therefore

increasing carbon input (manure) was a key to improve carbon sequestration in black soil region.