Distribution of glomalin-related soil protein and soil organic carbon in water-stable aggregate fractions of citrus rhizosphere

Author(s): Shuang Wang, Qiang-Sheng Wu

Soil organic carbon (SOC) and glomalin-related soil protein (GRSP) play an important role on soil aggregate stability, but few studies to examine distributive characteristics of these soil aggregate binding agents within water-stable aggregate (WSA) fractions. This study examined the distributive characteristics of SOC and GRSPs within five WSA sizes: macroaggregates (2.00–4.00, 1.00–2.00, 0.50–1.00 and 0.25–0.50 mm) and microaggregate (<0.25 mm) isolated from the rhizosphere of 24-year-old citrus trees (Citrus unshiu grafted on Poncirus trifoliata) in Jingzhou, China. Percentage of WSA2.00–4.00 mm was the highest and WSA<0.250 mmwas the lowest in the citrus rhizosphere. In general, easily-extractable GRSP (EE-GRSP) and totalGRSP (T-GRSP) were significantly higher inWSA0.50– 1.00mm and lower inWSA1.00–2.00 mm.Difficultly-extractableGRSP (DE-GRSP) increased with the increase of WSA sizes, but SOC increased with the decrease of WSA sizes. Among three GRSP fractions, only T-GRSP was significantly positively correlated withWSA.

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