有机肥增减施后红壤水稻土团聚体有机碳的变化特征

利用一个长达35 a水稻土长期定位试验,在保证原有定位试验继续正常开展的前提下,将部分原化肥处理增施有机肥,部分原有机肥处理改施化肥或者增施有机肥,研究有机肥增减施后长期不同施肥红壤性水稻土团聚体有机碳变化特征及影响。结果显示:红壤性水稻土以0.25 mm团聚体为主;长期不同施肥下土壤团聚体有机碳含量高低排序均表现为:0.25 mm团聚体0.25～0.053 mm团聚体(0.053 mm)团聚体,长期施用有机肥可提高红壤水稻土各粒级有机碳含量和2mm团聚体有机碳的贡献率。施肥对红壤性水稻土各粒径团聚体有机碳影响的大小排序为:0.053 mm0.25～0.053 mm(2 mm)2～0.25 mm;游离氧化铁和络合态铝对2～0.25 mm粒径团聚体有机碳有着重要影响,游离氧化铁在2 mm团聚体的形成中发挥作用。增加有机肥施用量可提高2 mm各粒级团聚体有机碳含量,减施有机肥则显著降低各粒级团聚体有机碳含量。不管减施还是增施有机肥均导致2mm团聚体有机碳贡献率降低;同时,减施有机肥后2 mm的各级团聚体有机碳贡献率提高,而增施有机肥后2～0.25 mm团聚体有机碳贡献率提高。

Characteristics of Soil Aggregate Organic Carbon (SAOC) in Paddy Soil After Increasing or Reducing Input of Organic Fertilizer

A long-term location experiment of 35 a paddy soil was utilized, with part of fertilization treatments changed to study the characteristics and influences of soil aggregate organic carbon(SAOC) under different fertilization treatments after increasing or reducing the input of organic fertilizer. The results showed that: red paddy soil was dominated by >0.25 mm aggregates; the contents of SAOC under different long-term fertilization treatments was characterized by: >0.25 mm macro-aggregates>0.25-0.053 mm microaggregates>(<0.053 mm)silty clay, meanwhile, the application of organic fertilizer increased organic carbon contents of different sizes of aggregates and the contribution rate of >2 mm aggregate organic carbon. The influence of fertilization on organic carbon of different sizes aggregates was ranked as follows: <0.05 mm <0.25-0.05 mm< (>2 mm)<2-0.25 mm; free iron oxide and chelated aluminum had important effects on organic carbon of 2-0.25 mm aggregates, and free iron oxide played a role in the formation of >2 mm aggregates. Increasing the input of organic fertilizer can increase the organic carbon content of <2 mm aggregates at each grain level, reducing the input of organic fertilizer significantly reduced organic carbon content of aggregates. Regardless of reducing or increasing the input of organic fertilizer, the contribution rate of organic carbon in >2 mm macro-aggregates decreased; at the same time, the contribution rate of organic carbon in <2 mm aggregates after organic fertilizer reduction was increased, and the contribution rate of organic carbon in aggregates of 2-0.25 mm was increased after organic fertilizer application.