Artificial Humic Acid Diminishes the Effect of Drought on the Soil Microbiome

Humic substances have an enormous potential for regenerative agriculture to improve soil quality and plant growth. Recently developed technologies called hydrothermal humification enabled the conversion of waste into artificial humic acids, that would allow for sustainable and large-scale applications. However, not much is known about the effect of artificially produced humic acid on the soil microbiome and its effect on drought-exposed soil. Therefore, we studied the effect of drought stress and artificial humic acid on the soil microbiota in sandy soil in a controlled experimental design. Analyses of 16S rDNA amplicon libraries by bioinformatics and statistics revealed that both drought and artificial humic acid application influenced bacterial community composition significantly, but only artificial humic acid affected bacterial diversity. Bacterial families like Pseudomonadaceae, Peptostreptococcaceae and Moraxellaceae enriched under artificial humic acid conditions, suggest an adaptation and selection of the soil bacterial microbiome. Under drought stress, artificial humic acid treatment kept bacterial diversity stable in the changed bacterial community composition. We propose that artificial humic acid application in sandy soil can improve the soil bacterial community, diminish drought stress, favour plant growth-promoting taxa, and bring enormous potential to sequestrate carbon in the soil.