Abstract: Glomalin as a recalcitrant glycoprotein produced by arbuscular mycorrhizal fungi is proved to improve soil structure, fix heavy metals in soils, and be a substantial contributor to soil carbon. At present, glomalin cannot be directly purified but can be quantified by measuring the content of glomalin-related soil protein (GRSP) in soil. Currently no standard procedure for GRSP measurement is available for all terrestrial ecosystems because of the non-specific nature of GRSP measurement. To investigate the possible influences of extraction time, centrifugal force, and centrifugal force before colorimetric test on GRSP measurement, we carried out a comparative study using latosolic red soils collected from a subtropical forest.  Higher centrifugal force extracted more easily extractable GRSP (EE-GRSP) for a given centrifuge time. Under 10 minutes of extraction, EEGRSP extracted with centrifugal force at 10000×g was 1.15-1.82 times more than at 5000×g, but the effect of centrifugal force on T-GRSP was not significantly different at α=0.05 level. Extending centrifugal time increased EE-GRSP concentration for a given centrifugal force. With the centrifugal force at 5000×g, EE-GRSP content increased significantly with the increase of centrifugation time from 10 minutes to 15 minutes. Centrifugation of the supernate with higher centrifugal force (≥10000×g) before colorimetric test significantly influenced the measurement of GRSP. The T-GRSP value reached 97.7%-99.8% of the theoretical maximum after 6 times of repeated extraction. Based on this study, the procedure for GRSP measurement for latosolic red soils in subtropical forests is recommended as centrifugation of soil solution at 10000×g for 10 minutes, and centrifugation of the supernate at 10000×g before colorimetric test.

Key words: relative humidity., temperature, urban wetland, shape feature