中文摘要：

调查采集了江汉平原不同土地利用和起源农田土壤表土样品,分析总有机碳（SOC）、热水溶性有机碳（HWEC）、易氧化有机碳（LOC）及其有机碳键合组分含量特征,并探讨有机碳量和与之影响的主要土壤因素的关系。结果表明：不同土地利用和起源均会影响土壤有机碳水平,表现为湿地起源水田有机碳含量（18.34±5.78）g/kg显著高于旱地（11.18±3.39）g/kg,而红壤水田有机碳含量（16.21±4.13）g/kg与旱地（14.54±3.41）g/kg之间差异不显著;不同起源水田下无显著差异,而红壤起源旱地显著高于湿地起源旱地。HWEC和LOC及其占SOC比例均表现为湿地起源水田显著高于红壤水田。不同土地利用和起源下土壤有机碳的稳定机制不同,粘粒保护在湿地起源土壤中具有显著作用,而水田条件下,土壤有机碳的化学结合稳定显得与游离氧化铁的保护有关,红壤起源水田土壤中由于游离氧化铁的大量存在,这种保护作用对于土壤有机碳的稳定具有显著的贡献。

英文摘要：

Topsoil samples were collected from croplands with different land uses and soil origins in Jianghan plain,Hubei province,China.Total soil organic carbon（SOC） content and fractions of hot water extractable carbon（HWEC）,labile organic carbon（LOC）,calcium-and iron oxyhydrate-bound organic carbon were analyzed.Relationship between SOC content and the related main soil factors was investigated.SOC was affected by different land use patterns and soil origins： In soils reclaimed from wetlands,SOC contents in rice paddies（18.34±5.78） g/kg was significantly higher than that in dry croplands（11.18±3.39） g/kg;while in soils reclaimed from red soils,that in rice paddies（16.21±4.13） g/kg did not differ significantly from that in dry croplands（14.54±3.41） g/kg.SOC contents in rice paddies did not show significant difference between soils reclaimed from wetlands and red soils;whereas that in dry croplands reclaimed from red soils was significant higher than that from wetlands.HWEC and LOC as well as ratios of HWEC to SOC and of LOC to SOC in rice paddies reclaimed from wetlands were significant higher than that from red soils.Mechanisms of SOC stabilization varied with different land use patterns and soil origins： Clay protection played an important role in soils reclaimed from wetlands;while in paddy soils,SOC chemical stabilization appeared to relate to the protection of free oxidized iron.Protection of oxidized iron had a significant contribution to SOC stabilization in rice paddies reclaimed from red soils due to the large amount of free oxidized iron.