不同施肥处理对黑垆土各粒级团聚体中有机碳含量分布的影响

EFFECT OF FERTILIZATION ON ORGANIC CARBON DISTRIBUTION IN VARIOUS FRACTIONS OF AGGREGATES IN CALICHE SOILS

依托中国科学院黄土高原长武农业生态试验站中的长期定位试验(始于1984年),利用湿筛法获得不同粒径的团聚体,研究了长期施肥对不同粒级水稳性团聚体中有机碳分布的影响。试验涉及化肥和轮作培肥两个长期试验的9个处理。化肥试验:同一施磷基础上的5个施氮水平(N0、N45、N90、N135、N180);轮作培肥试验:不施肥(CK)、化肥(NP)、有机肥(M)、化肥有机肥配施(NPM)。结果表明:长期施肥显著影响土壤水稳性团聚体含量(p<0.05),提高了>2mm粒级水稳性团聚体含量,降低了<0.25mm水稳性团聚体含量。施氮(N45、N90、N135、N180)处理主要提高了>5mm、0.5～0.25mm水稳性团聚体中有机碳的含量,与N0相比,提高量为44.3%～73.3%;有机肥(M、NPM)处理对各粒级团聚体中有机碳的含量均有提高,与CK相比,提高量为40.7%～92.2%,其中>5mm团聚体中有机碳含量分别提高了66.7%和92.2%。低氮(N0、N45、N90)处理、不施肥(CK)处理的1～0.5mm团聚体中的有机碳对土壤有机碳的贡献率最大,占13.7%～23.7%;高氮(N135、N180)处理和氮磷配施(NP)处理、有机肥(M、NPM)处理的>5mm团聚体中的有机碳对土壤有机碳的贡献率最大,占17.3%～24.9%。土壤有机碳与>5mm、5～2mm团聚体含量呈显著正相关关系,与<0.25mm团聚体含量呈极显著负相关。

Various particle-size fractions of soil aggregates were obtained with the wet-screening method from the soil of a long-term stationary fertilization experiment（since 1984） field of the Changwu State Key Loess Plateau Agro-Ecological Experimental Station of the Chinese Academy of Sciences,Northwest China,for analysis of effect of long term fertilization on soil organic carbon distribution in water-stable aggregates of different particle-size fractions.The experiment had five N treatments（N0,N45,N90,N135,and N180）,which were all the same in P application rate,and four fertilization treatments,that is,CK（unfertilized）,NP（nitrogen and phosphorus）,M（farmyard manure）,and NPM（nitrogen and phosphorus plus farmyard manure）.Results show that long-term fertilization significantly affected water-stable aggregates distribution（p0.05）,increasing the content of macro aggregates（2 mm） and decreasing that of micro aggregates（0.25 mm）.Nitrogen fertilization significantly increased soil organic carbon（SOC） content in the 0.5～0.25 mm and5mm water-stable aggregates by 44.3%～73.3%,compared to that in Treatment N0.Moreover,Treatments M and NPM increased SOC content in aggregates of all particle sizes by 40.7%～92.2% over CK,and in the 5 mm aggregates by 66.7% and 92.2%,respectively.Treatments N0,N45 N90and CK contributed the most to the soil organic carbon content in the 1～0.5 mm water-stable aggregates,accounting for 13.7%～23.7%.Treatments N135,N180,NP,M and NPM contributed the most to the SOC content in the5 mm aggregates,accounting for 17.3%～24.9%.SOC was positively related to the content of the5 mm and 5～2 mm water-stable aggregates,but negatively related to the content of the0.25 mm water-stable aggregates.