不同种植模式对土壤团聚体及有机碳组分的影响

Effects of Different Cultivation Patterns on Soil Aggregates and Organic Carbon Fractions

结合在有机农场近10年的定位研究,通过同步采样分析,比较了有机种植和常规种植两种不同模式下土壤团聚体组成、分配及团聚体内有机碳组分的差异.结果表明,常规种植模式下随着团聚体粒级的减小,团聚体4个粒级(>1 mm、1~0.5 mm、0.5~0.25 mm和<0.25 mm)的含量均值分别为23.75%、15.15%、19.98%和38.09%,而有机种植模式下各粒级团聚体(>1 mm、1~0.5 mm、0.5~0.25 mm和<0.25 mm)的含量分别为9.73%、18.41%、24.46%和43.90%,<0.25 mm微团聚体含量显著高于常规种植.有机种植模式提高了土壤有机碳和全氮含量,平均值分别为17.95 g·kg-1和1.51 g·kg-1.有机种植模式下相同粒级间,团聚体中重组有机碳平均含量显著高于常规种植,且重组有机碳在<0.25 mm这部分稳定性有机碳主要储存场所的微团聚体中富集.有机种植模式下易氧化态碳在>1 mm大团聚体中的含量显著高于常规种植,其它粒级间没有显著差异,易氧化态碳在>1 mm大团聚体中富集.有机种植模式增加了土壤有机碳及其组分含量,缓解了耕作对团聚体的破坏,并增强了有机碳的稳定性.有机种植有利于土壤固碳,这为进一步加快我国有机农业的发展提供了理论依据.

Combined with the research in an organic farm in the past 10 years,differences of soil aggregates composition,distribution and organic carbon fractions between organic and conventional cultivation were studied by simultaneous sampling analysis. The results showed that the percentages of aggregates( > 1 mm,1-0. 5 mm,0. 5-0. 25 mm and < 0. 25 mm) in the conventional cultivation were23. 75%,15. 15%,19. 98% and 38. 09%,while those in organic cultivation were 9. 73%,18. 41%,24. 46% and 43. 90%,respectively. The percentage of < 0. 25 mm micro-aggregates was significantly higher in organic cultivation than that in conventional cultivation. Organic cultivation increased soil organic carbon( average of 17. 95 g·kg- 1) and total nitrogen contents( average of 1. 51g·kg- 1). Among the same aggregates in organic cultivation,the average content of heavy organic carbon fraction was significantly higher than that in conventional cultivation. This fraction accumulated in < 0. 25 mm micro-aggregates,which were main storage sites of stable organic carbon. In organic cultivation,the content of labile organic carbon in > 1 mm macro-aggregates was significantly higher than that in conventional cultivation,while no significant difference was found among the other aggregates,indicating that the labile organic carbon was enriched in > 1 mm macro-aggregates. Organic cultivation increased the amounts of organic carbon and its fractions,reduced tillage damage to aggregates,and enhanced the stability of organic carbon. Organic cultivation was therefore beneficial for soil carbon sequestration. The findings of this research may provide theoretical basis for further acceleration of the organic agriculture development.