Effects of conservation tillage patterns on content and density of organic carbon of black soil

Based on the long-term (10 years) conservational tillage experiment in Gongzhuling city, the effects of minimal tillage patterns (MTs) and conventional tillage pattern (CT) on soil sequestrated carbon were analyzed. Four tillage patterns were designed as follows: fall moldboard plowing and harrowing ridge (called as CT); fall stubbing ridge (called as MT1); deep loosing tillage (called as MT2); wide-narrow row alternation fallow (called as MT3), the last three minimal tillage patterns were regarded as conservation tillage patterns. Results showed that different tillage patterns had a significant effect on the soil organic carbon for a 10 years tillage experiment. CT and MT1 had the lowest soil organic carbon content in the surface layer (0–20 cm); organic carbon content of MT2 pattern was significantly 13.49%–25.14% lower than that of other tillage patterns in deeper layer (30–50 cm); organic carbon content of MT3 was 0–33.58% higher than that of other tillage patterns. Active and slow organic carbon content of loosing belt of MT3 was 8.06%–48.87% and 0–33.83% higher than that of other patterns, respectively. Soil organic carbon density of MT2 pattern and seeding belt of MT3 pattern was 10.95% lower and 17.13% higher than that of CT; active and slow organic carbon density of seeding belt of MT3 in 20–50 cm was 2.20%–18.85% and 17.00%–29.19% higher than that of other tillage patterns; passive organic carbon density of different tillage patterns had no significant variance. In contrast to CT, different conservation tillage patterns could increase soil organic carbon density or reduce soil organic carbon density. MT3 pattern increases soil organic carbon density through the increasing of soil active and slow organic carbon density, which is the most beneficial tillage pattern for soil organic carbon sequestration and quality improvement of soil organic carbon in northeast region.