Effect of Wetland Reclamation on Soil Aggregates Content and Soil Organic Carbon Distribution of Aggregates in Peat Mire Soil around Xingkai Lake in Northeast China

摘要

Soil aggregates content, soil organic carbon (SOC) concentration and density in soil aggregates in 0～5, 5～10, 10～20, 20～30 cm soil layers in peat mire soil in wetland, soybean and paddy field reclaimed from the wetland around Xingkai Lake were determined to investigate how reclamation of wetland for soybean and rice farming impacts soil aggregates content and SOC distribution of aggregates. After reclamation, >1 mm macro-aggregates decreased, 0.25～1mm macro-aggregates and micro-aggregates (0.053～0.25 mm and <0.053 mm) increased. In 0～5, 5～10, 10～20, 20～30 cm soil layers <0.25mm micro-aggregates content in soybean field were higher than in paddy filed by 10.18%, 11.2%, 3.35% and 13.13%, respectively. Wetland reclamation has reduced SOC concentration of aggregates and soil. SOC concentration in aggregates in soybean field was higher than in paddy field except in <0.053 mm micro-aggregates in 0～5 cm and 10～20 cm soil layers. SOC density in 0～30 cm soil layer was ordered from high to low as wetland>soybean field>paddy field. Due to reclamation, SOC density in <0.25 mm micro-aggregates in the four soil layers and its share in total soil SOC increased, and that in soybean field was higher than in paddy field. More SOC was allocated into <0.25mm micro-aggregates and might be protected better in soybean field than in paddy field, and reclaim the wetland into soybean field instead of paddy field is more beneficial for the long-term retention of SOC.