Accumulation and Chemical Composition of Glomalin Regulated by Different Factors Across Land Uses in China

ABSTRACT Glomalin, or glomalin‐related soil proteins (GRSPs), are persistent and sticky glycoproteins released by arbuscular mycorrhizal fungi that are widely distributed in soil. Although the potential role of GRSPs in augmenting soil quality has been recognised, few studies have simultaneously focused on the variation and regulation of their amount, composition, and contribution to soil carbon (C) storage across diverse land use types. In this study, a nationwide survey was conducted in forests, grasslands, croplands, and deserts across China to determine the GRSP accumulation and changes in their chemical composition across these landscapes. The mean total GRSP content was highest in forests (~9.08 mg g −1 ), followed by grasslands (~5.71 mg g −1 ), croplands (~4.33 mg g −1 ), and deserts (~1.18 mg g −1 ). Three‐dimensional fluorescence spectroscopy revealed that the dominant components of GRSPs were tryptophan‐like proteins in forests, autochthonous original protein‐like components in grasslands, terrestrial humic‐like compounds and tyrosine‐like proteins in croplands, and terrestrial humic‐like compounds in deserts. The contribution of total GRSPs to soil C was ~30.59% in grasslands, ~25.50% in croplands, ~23.26% in forests, and ~ 10.31% in deserts. Redundancy analysis showed that specific soil nutrient variables (NH 4 + –N, NO 3 + –N, and the C/N ratio) explained most of the variation in GRSP content and their contribution to soil C, while climatic conditions (mean annual temperature and precipitation along with altitude) had a stronger regulatory effect on the GRSP chemical characteristics. The partial least squares path modelling further demonstrated that the land use type, directly or indirectly, influenced GRSP production, while the climatic condition was more inclined to affect their decomposition. We believe this work can enhance the understanding of the role of GRSPs in soil C sequestration for sustainable land management.