长期施肥对红壤性水稻土团聚体活性有机碳的影响

在23年的长期田间定位试验区,研究了长期施肥对红壤性水稻土团聚体活性有机碳含量的影响。结果表明,在不施肥(CK)、无机肥(NPK)、有机肥(猪粪+紫云英绿肥)(OM)和无机肥与有机肥配施(NPKM)处理中,土壤团聚体活性有机碳含量均随深度的增加而降低。长期施用肥料,特别是有机肥与无机肥配施会提高土壤团聚体活性有机碳含量,从而保持和提高土壤有机碳库质量。不同粒级土壤团聚体中活性有机碳含量和团聚体活性有机碳占团聚体有机碳比率有差异,潜在可矿化碳含量和潜在可矿化碳占团聚体有机碳比率从高到低的顺序为:0.25~1mm、1~3mm、>3mm、0.05~0.25mm和<0.05mm;而可溶性有机碳含量和可溶性有机碳占团聚体有机碳比率从高到低的顺序为:0.05~0.25mm、0.25~1mm、1~3mm、>3mm和<0.05mm。不同施肥处理A层土壤团聚体潜在可矿化碳、可溶性有机碳含量都与土壤团聚体有机碳含量都呈极显著相关;P层除1~3mm团聚体外都呈显著相关。土壤微团聚体(<0.25mm)中有机碳的稳定性高于大团聚体(>0.25mm)。

EFFECTS OF LONG-TERM FERTILIZATION ON LABILE ORGANIC CARBON IN SOIL AGGREGATES IN RED PADDY SOIL

A long-term field experiment has been carried out for 23 years in Jinxian County Institute of Red Soil in Jiangxi Province(116b20c24°E,28b15c30°N).One of the aims of the experiment is to study effects of longterm fertilization on labile organic carbon pool in soil aggregates in red paddy soil.It is designed to have the following treatments,i.e.1) Zero fert ilization(CK),2) chemical fert ilizers alone(NPK),3) organic fertilizers alone(OM),and 4) combinat ion of chemical and organic fertilizers(NPKM).Results show that content of labile organic carbon in soil aggregates decreased with soil depth.Long-term application of fertilizer,especially in Treatment NPKM,increased content of labile organic carbon in soil aggregates,thus preserving and improving quality of the soil carbon pool.Content of labile organic carbon and percentage of soil labile organic carbon to total soil organic carbon differed between aggregates different in size fraction.In terms of content of potent ial mineralization carbon(PMC) and percentage of PMC to total soil organic carbon,aggregate size fractions followed a decreasing order of 0.25~1 mm,1~3 mm,> 3 mm,0.05~0.25 mm,and < 0.05 mm,whereas in terms of percentage of content of dissolved organic carbon(DOC) to total soil organic carbon,they did a decreasing one of 0.05~0.25 mm,0.25~1 mm,1~3 mm,> 3 mm,and < 0.05 mm.Contents of PMC and DOC in aggregates were significantly related to content of SOC(p< 0.01) in A horizons of all treatments,and in soil P horizon as well,except for the size fraction of 1~3 mm(p< 0.05).Micro-aggregates(< 0.25 mm) was higher than macro-aggregates(> 0.25 mm) in stability.