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采用湖南省4个23年连续施肥的稻田长期定位试验,研究了施肥对湖南省水稻土有机碳分布及化学键合形态的影响。试验设不施肥(CK)、化肥(NPK)、中量有机肥(MOM)和高量有机肥(HOM)4个处理。结果表明:在所有施肥处理中,水稳性团聚体均以0.25～1mm和2～5mm粒径含量最高,分别达全土总量的18%～43%和13%～48%。中、高量有机肥处理显著增加了>1mm大团聚体含量以及有机碳在大团聚体中的分配,其中0.25～1mm和1～2mm粒径团聚体中有机碳含量均略高于其余粒径组。与不施肥比较,钙结合态有机碳(Ca-SOC)占总有机碳的比例在2%～4%左右且随有机肥施用呈下降趋势,而铁铝结合态有机碳Fe(Al)-SOC占总有机碳的18%～33%呈上升趋势。有机肥施用条件下,有机碳在大团聚体中的分布的增加、Fe(Al)-SOC的提升以及Ca-SOC的降低意味着土壤有机碳物理和化学保护作用的增强,有利于稻田土壤有机碳的积累,是有机肥施用条件下保持稻田土壤较高固碳速率的重要原因。
The long-term experiment of four years of continuous paddy field fertilization in Hunan Province was conducted to study the effects of fertilization on the distribution of organic carbon and chemical bonding morphology of paddy soil in Hunan Province. The experiment included 4 treatments of CK, NPK, MOM and HOM. The results showed that the water-stable aggregates had the highest contents of 0.25-1 mm and 2-5 mm in all fertilization treatments, reaching 18% -43% and 13% -48% of the total soil, respectively. Medium and high organic manure treatments significantly increased the content of> 1 mm macroaggregates and the distribution of organic carbon in macroaggregates. The contents of organic carbon in the aggregates of 0.25-1 mm and 1-2 mm were slightly higher than those of the other group. Compared with non-fertilization, the ratio of Ca-SOC to total organic carbon was about 2% -4% and decreased with the application of organic manure, while Fe-Al-organic carbon Fe (Al) -SOC Accounting for 18% to 33% of total organic carbon is on the rise. Under organic manure application, the distribution of organic carbon in large aggregates, the increase of Fe (Al) -SOC and the decrease of Ca-SOC mean that the physical and chemical protection of soil organic carbon is enhanced, Carbon accumulation is an important reason for maintaining high carbon sequestration rate in paddy soils under the condition of organic manure application.