Optimization of glomalin-related soil protein extraction in soil of citrus (Citrus species) orchard

The study was undertaken to analyze the effects of high temperature autoclaved time, centrifugal time and weight of soil samples on glomalin-related soil protein (GRSP) concentration in Xanthi-Udic ferralsol of a citrus (Citrus species) orchard. The results showed that extraction of easily-extractable GRSP should adopt the following protocol: 0.75 g soil sample was incubated in 6 ml 20 mM citrate buffer (pH 7.0), which was autoclaved at 0.11 Mpa and 121°C for 1 h, and centrifugated at 10, 000×g for 20 min. For the determination of difficultly-extractable GRSP, the residual of EE-GRSP extraction was mixed with 8 ml 50 mM citrate buffer (pH 7.0), autoclaved at 121°C and 0.11 Mpa for 1 h, and centrifugated at 10, 000×g for 10 min. Extraction of GRSPs in different soil types still needs to be checked.