连作年限对棉田土壤团聚体有机碳分布的影响

研究棉田土壤团聚体有机碳分布对不同连作年限的响应,为棉田土壤固碳提供理论依据。以连作5、12、17年(L₅、L₁₂、L₁₇)棉田土壤为研究对象,分析不同连续种植年限条件下,土壤团聚体分布及团聚体有机碳含量。结果表明,与种植1年对照CK处理相比,连作17年处理,0~20、20~40 cm土层>2 mm粒径团聚体百分含量较对照分别显著降低16.7%、13.2%(P<0.05);各土层,连作5年处理土壤有机碳含量最高,分别为11.8、10.6 g/kg,较对照显著提升16.2%、15.1%;土壤团聚体有机碳贡献率以>2 mm粒径最大,占50%以上,<0.053 mm粒径的碳贡献率最小。连作不利于土壤质量的保持,但短期连作对土壤有机碳的积累起正向作用。在本试验条件下,连作5年土壤有机碳含量最大,连作5年后有机碳含量逐渐降低。

Effects of Continuous Cropping Years on Organic Carbon Distribution in Soil Aggregates in Cotton Fields

This study aims to clarify the response of organic carbon distribution in cotton soil aggregates to different continuous cropping years. Taking cotton field soil of 5, 12 and 17 years’ continuous cropping (L₅, L₁₂ and L₁₇) as the research objects, the soil aggregates’ distribution and organic carbon content were analyzed. The results showed that compared with that of the control (1 year cotton planting), the content of aggregates >2 mm decreased after continuous cropping for 17 years by 16.7% and 13.2% in 0-20 cm and 20-40 cm soil layer respectively. The content of soil organic carbon increased after continuous cropping for 5 years, which were the highest of 11.8 g/kg and 10.6 g/kg in 0-20 cm and 20-40 cm soil layer respectively, significantly increased by 16.2% and 15.1% compared with that of the control. The contribution rate of soil aggregates>2 mm to organic carbon was the highest, accounting for more than 50%, while the aggregates<0.053 mm had the lowest contribution rate. In conclusion, though continuous cropping was not conducive to the maintenance of soil quality, short-term continuous cropping was beneficial to the accumulation of soil organic carbon. In this experiment, the soil organic carbon content reached the maximum after 5 years of continuous cropping, and then decreased gradually.