长期施肥对红壤性水稻土活性碳的影响

Effects of long-term different fertilization on labile organic carbon in red paddy soil

在23年的长期田间定位试验区,研究了不同施肥对红壤性水稻土活性碳的影响。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,土壤微生物量碳含量、潜在可矿化碳含量和可溶性有机碳含量均随土层深度的增加而降低;不同施肥处理土壤微生物量碳含量、潜在可矿化碳含量和可溶性有机碳含量从高到低顺序都为:NPKM>OM>NPK>CK,长期施用肥料,特别是施有机肥与无机肥配施能提高土壤微生物量碳、潜在可矿化碳和可溶性有机碳含量,从而保持和提高土壤碳库质量。同施肥处理A层的土壤活性碳占土壤有机碳的比率显著大于P层;同施肥处理同发生层各土壤活性碳占土壤有机碳比率从高到低的顺序为:潜在可矿化碳的比率(R2)>微生物量碳的比率(R1)>可溶性有机碳的比率(R3);同施肥处理同发生层土壤活性碳占土壤有机碳比率R1、R2、R3大小顺序都为:NPKM>OM>NPK>CK。除P层微生物量碳和可溶性有机碳之间外,土壤有机碳总量与各活性碳之间以及各类活性碳之间相关性均达到极显著水平。

A long-term field experiment was set in Jiangxi Institute of Red Soil （116°20′24＂E, 28°15′30＂N） in Jinxian county of Jiangxi province, China. One of the aims of the experiment was to study the effects of extensive use of various fertilisers over a long period of time on labile organic carbon pool in red paddy soil. The treatments on use of fertilizers were： （1） no added fertiliser （CK）, （2） chemical fertilizers only （NPK）, （3） organic fertilizers only （OM） and （4） a combination of chemical and organic fertilisers （NPKM）. Results showed contents of soil microbial biomass carbon （MBC）, potential mineralization carbon （PMC） and dissolved organic carbon （DOC） in red paddy soil decreased as the soil depth increased. Contents of MBC, PMC, DOC at same soil horizon in different fertilizations decreased in an order of NPKM〉OM〉NPK〉CK. Extensive use of organic fertilizers or a combination of organic and inorganic fertilizers increased MBC, PMC and DOC in red paddy soil, resulting in an increased soil carbon pool. The percentage of different forms of labile organic carbon over the total soil carbon in the A horizon was significantly higher than that in P horizon. And at the same soil horizon, it was found that the percentage of PMC to total soil carbon （R2）〉 the percentage of MBC to total soil carbon （R1）〉 the percentage of DOC to total soil carbon （R3）. Under different fertilizations, the percentages of the labile organic carbon to total soil carbon was NPKM〉OM〉NPK〉CK. It was also found that soil labile organic carbon were not only significantly correlated to soil organic carbon but also interrelated themselves.