In agroecosystems, fertilization management significantly influences soil quality and the microbial community structure as well as its stability. However, the relationship between improved farmland soil quality and microbial community stability has remained unclear.

In a study published in European Journal of Soil Science, researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences investigated the effects of long-term fertilization management on soil quality and microbial community stability, and found that soil bulk density and pH are critical and direct factors regulating the temporal stability of soil bacteria and fungi in agricultural systems.

Based on a long-term field experiment from 1982 to 2015, researchers investigated the effects of fertilization management on soil properties and microbial community dynamics, including no fertilization, natural recovery, mineral fertilizers, combined wheat straw incorporation, and cattle manure organic fertilizer. By analyzing the temporal dynamics of soil microbial co-occurrence networks, they evaluated the relationship between the community stability and soil quality.

Researchers found that fertilization changed farmland quality, however, there was no correlation between soil quality and the robustness, vulnerability, or compositional stability of bacterial and fungal co-occurrence networks. Fertilization management indirectly regulated microbial community structure by altering soil physicochemical properties, but microbial community stability (e.g., robustness and vulnerability) did not increase with the improvements in soil quality.

Among the 14 soil parameters analyzed, soil bulk density was found to be a major contributor to the compositional stability of both bacterial and fungal communities. Its influence was bigger than the microbial diversity metrics and dissolved organic carbon. Soil pH and microbial diversity were also found to be significant regulators.

Furthermore, researchers found that long-term application of cow manure combined with mineral fertilizers improved the microbial community stability more effectively than mineral fertilizers alone or with straw return. Fertilization management directly altered microbial composition stability, independent of seasonal changes.

“Our study represents the first exploration of the relationship between farmland soil quality and microbial community stability, providing an important theoretical basis for improving the stability of farmland soil microbial communities,” said LIU Changan from XTBG, one corresponding author of this study.