Abstract: Glomain-related soil protein (GRSP) is an important indicator in assessing soil health. On the basis of the researches done by predecessors,further investigations were conducted of effects of soil particle size,soil sample storage conditions and delay of centrifugation of the extract after high-temperature extraction on quantification of GRSP with the Bradford method.Results show that soil particle size significantly affected extraction and determination of easily extracted GRSP(EEG).The content of EEG extracted from samples that passed a 0.074 mm sieve was significantly higher than that from samples that passed 0.149,0.25,and 1 mm sieves,separately.However,the content of total GRSP(TG)did not vary with soil particle size,which indicate that for determination of TG,it is advisable to use soil samples that pass 1 mm sieves.Storage conditions also affected determination of EEG and TG.The content of EEG determined of the soil samples of low organic matter content at -20℃ for 18 months was obviously more than that stored at room temperature for the same length of time,while the content of EEG determined of soil samples of high organic matter content stored at room temperature showed a reverse trend.And TG determined of soils of three organic matter content levels stored at room temperature was obviously higher than that stored at -20℃.So to minimize the effect of organic matter degradation,soil samples should be stored at low temperature.Delay of centrifugation of extracts may lead to decrease in the value of EEG determination.It is advisable to have the extract centrifugated within 1h.However,there is no significant difference betwwen delays of centrifugation within 2 h for TG determination.

Key words: Braford method, glomalin-related soil protein(GRSP), soil particle size, storage condition, delay of centrifugation