The Innovation Team of Improvement and Amelioration of Soil Fertility at the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS) has revealed the mechanism by which long-term fertilization affects the accumulation of glomalin-related soil proteins (GRSP). The results provide scientific evidence for optimizing soil quality management. The findings were published in "Soil & Tillage Research" with the title of "Long-term manuring facilitates glomalin-related soil proteins accumulation by chemical composition shifts and macro-aggregation formation".

GRSP, as a highly adhesive, hydrophobic, and persistent protein substance, plays a crucial role in maintaining soil structure stability and carbon sequestration. However, the impacts of long-term fertilization on the accumulation characteristics of GRSP and its association with arbuscular mycorrhizal fungi (AMF) communities and diversity remain unclear. In this study, based on the Qi'yang Soil Quality Monitoring Experiment Station, the evolving characteristics of GRSP in upland red soil under different long-term (29 years) fertilization management were analyzed, along with the AMF community structure and diversity. Results showed that GRSP contents increased over years across fertilization treatments. Compared with the control (without fertilization), the application of organic fertilizer and straw returned significantly increased the content of GRSP by 100% and 80%, respectively, as well as the proportion of recalcitrant (aromatic) carbon in GRSP. These changes were primarily regulated by the AMF community structure and diversity.

Furthermore, the application of organic fertilizer promoted the formation of macro-aggregates (>250 μm) and enhanced the physical protection of GRSP. Structural equation modeling showed that soil macro-aggregates, AMF biomass and diversity, and the chemical composition of GRSP had positive effects on the accumulation of GRSP. In conclusion, long-term application of organic fertilizers promotes the accumulation of GRSP in the soil through the modulation of AMF-mediated changes in the chemical composition of GRSP (especially aromatic carbon) and the physical protection provided by macro-aggregates. These research findings provide a scientific basis for optimizing sustainable management of cropland soils and enhancing soil fertility.

Figure 1: Conceptual diagram illustrates the long-term fertilization regulation of glomalin-related soil protein accumulation.

Yang Hongbo, a doctoral student in joint training between the IARRP, and the University of Liège, is the first author of the paper, and Prof. Zhang Wenju is the corresponding author. This study was supported by the National Key Research and Development Program and the National Science and Technology Fundamental Resources Investigation Project.

Paper link: https://doi.org/10.1016/j.still.2023.105904