Based on a long-term experiment in Zhaozhou County

Daqing City

Heilongjiang Province in 1995

the effects of long-term application of organic manure on labile organic matter(LOM) and carbon manage- ment index(CMI)were studied

which supplies evaluation indicators for improving meadow alkaline soil.Highly labile organic matter(HLOM)

middle labile organic matter(MLOM) and LOM were determined using oxidation method at 3 KMnO4

concentrations(33

167 and 333 mmol/L).Results from the experiment indicated that LOM concentrations and CMIs were significantly increased by long-term application of organic manure in meadow alkaline soil.Each component of LOM concentrations and CMIs were increased by applicanon of organic manure

and were consistent with crop yield increasing

respectively.After the 5 years of application of organic manure

each component of LOM concentrations and CMIs reached the highest values

respectively.But each component of LOM concentrations and CMIs were gradually decreased and finally stabilized.There were significant positive correlations among MLOM and LOM and total organic matter(TOM)

but no correlation between HLOM and TOM.There was also highly significant positive correlation between each component of LOM and CMIs.The study indicates that TOM cannot be used as a good indicafor of soil fertility in meadow alkaline soil.MLOM

LOM and CMI objectively reflect soil fertility in meadow alkaline soil and thus may be used as indicators for improving the soil.