The different enhancement effects of straw (S), biochar (B), woody peat humic acid (HA) and woody peat humic acid-ferrihydrite complex (HA-Fe) on soil organic carbon content in newly reclaimed red soil, coastal saline soil and loessal soil were explored through an incubation experiment. The results showed that during the entire incubation period, all four organic materials significantly increased the total organic carbon (TOC) content of the three soils. However, after 100 days of incubation, the enhancement effects of HA, B and HA-Fe were 3.1-4.3, 3.1-3.8 and 3.0-4.0 times of S, respectively. After 360 days of incubation, the enhancement effects of HA, B and HA-Fe were 3.0-7.1, 2.9-6.2 and 2.9-6.3 times of S, respectively. The enhancement effects of B and HA on soil mineral-associated organic carbon (MAOC) were weaker than that of S. Compared to S, B and HA, HA-Fe significantly increased both TOC and MAOC. However, its enhancement effect on soil readily oxidizable carbon was much smaller than that of S. This study reveals that HA-Fe has a stronger ability to rapidly enhance soil organic matter of newly reclaimed lands, but it is better to apply with liable organic materials to more quickly enhance soil active organic matter and mineral-associated organic matter.