不同施肥处理对红壤性水稻土微团聚体有机碳汇的影响

Effects of different fertilization on soil organic carbon distribution and storage in micro-aggregates of red paddy topsoil

在田间定位试验区 ,研究了不同施肥处理对表层红壤性水稻土微团聚体组成以及土壤有机碳在各级微团聚体中分布和赋存的影响。结果表明 ,红壤性水稻土中 0 .0 2～ 0 .0 5 mm微团聚体所占比例最大 ,达 4 0 % ;其次是 0 .0 0 2～ 0 .0 2 mm和 0 .0 5～0 .1mm的微团聚体 ;>0 .2 mm微团聚体占的比例最小。长期施用无机肥 (NPK)、有机肥 (猪粪 +紫云英绿肥 ) (OM)、无机肥与有机肥配施 (NPKM) ,能显著增加 0 .0 0 2～ 0 .0 2 mm微团聚体的含量而降低 <0 .0 0 2 m m微团聚体的含量。土壤有机碳含量与0 .0 0 2～ 0 .0 2 mm微团聚体含量之间呈显著正相关关系 ;而与 <0 .0 0 2 mm微团聚体含量呈显著负相关关系。各级微团聚体有机碳含量从高到低顺序为 :>0 .2 mm,0 .1～ 0 .2 mm,<0 .0 0 2 m m,0 .0 5～ 0 .1m m,0 .0 0 2～ 0 .0 2 mm,0 .0 2～ 0 .0 5 m m。 OM、NPKM处理能显著增加 >0 .0 0 2 mm各级微团聚体有机碳的赋存量 ,新增加的有机碳主要向微团聚体 0 .1～ 0 .0 5 m m,0 .0 5～ 0 .0 2 mm和 0 .0 2～ 0 .0 0 2 mm富集 ,它们是土壤有机碳的主要载体。 3种施肥处理对提高土壤有机碳赋存效果高低顺序为 :NPKM>OM>NPK。

A long-term field experiment was set in Jinxian County, Institute of Red Soil of Jiangxi Province (N28°15′ 30″, E116°20′ 44″). One of the aims of the experiment was to study soil organic carbon (SOC) distribution and storage in different size groups of micro-aggregate in surface layer (0-17cm) of red paddy soil impacted by different fertilizers. Treatments were: (1) zero fertilization (CK), (2) chemical fertilizers along (NPK), (3) organic fertilizers along (OM) and (4) a combination of chemical and organic fertilizers (NPKM). A modified method was used for separating micro-aggregates. Results showed that soil micro-aggregate in size group 0.02～0.05mm occupied >40% of the total from all treatments. The percentage of the rest size group decreased in the following order: 0.002～0.02mm, 0.05～0.1mm, 0.1～0.2mm, <0.002mm and >2mm. Long-term application of different fertilizers significantly increased the micro-aggregate size group of 0.002～0.02mm and decreased the size group <0.002mm as compared with zero fertilization (CK). Results also showed that soil organic carbon increased in all fertilized treatments and the concentration decreased in the sequence of NPKM> OM> NPK> CK. The amount of SOC and the amount of size group of 0.002～0.02mm had positively linear relationship, while the relationship with the quantity of size group <0.002mm was negatively linear.The content of SOC in different size groups decreased in the sequence of >0.2mm, 0.1～0.2mm, <0.002mm, 0.05～0.1mm, 0.002～0.02mm, 0.02～0.05mm. However, compared to the SOC content in all size groups among treatments, the OM and NPKM were significantly higher than those in corresponding size group of micro-aggregate of NPK and CK. As to the treatment of NPK, only the SOC content of >0.2mm group was prominently higher than that in relevant group of CK. The storage of total SOC increased in the sequence of CK < NPK < OM < NPKM. Compared to SOC storage in different size groups, it was significantly decreased in <0.002mm group but was increased in the group of >002mm among treatments. The newly enriched organic carbon mostly appeared in size groups of 0.1～0.05mm, 0.05～0.02mm and 0.02～0.002mm, so they were main carriers of SOC storage. Results indicated that long-term application of organic fertilizer, or combination of organic and inorganic fertilizer significantly promotes soil organic carbon sequestration in red paddy soil.