Changes of soil-rhizosphere microbiota after organic amendment application in a Hordeum vulgare L. short-term greenhouse experiment

Aims: In order to counteract the enduring decreases in the quality of agricultural land, mechanistic studies for a more sustainable agricultural crop production were performed. They aimed to assess the effects of organic amendments in combination with mineral fertilizer on soil-rhizosphere microbiota and their influence on soil health and plant performance. Methods: In a short-term greenhouse experiment, the effects of pelletized spent mushroom substrate, with different combinations of biochar and mineral fertilizer, on agricultural soil and performance of Hordeum vulgare L were scrutinized. To evaluate improved soil quality, different soil biological and chemical properties, microbial activity, bacterial diversity and plant performance were assessed. Results: Plant performance increased across all fertilizer combinations. Bacterial β-diversity changed from the initial to the final sampling, pointing at a strong influence of plant development on the rhizosphere with increasing abundances of Acidobacteria and decreasing abundances of Actinobacteria, Chloroflexi, and Bacteroidetes. Microbial activity (FDA), potential enzyme activity and metabolic diversity of the microbial community (BIOLOG) were not affected by the amendments, whereas bacterial community structure changed on family level, indicating functional redundancy. Treatments containing biochar and the highest amount of mineral fertilizer (B_MF140) caused the strongest changes, which were most pronounced for the families Xanthobacteraceae, Mycobacteriaceae, and Haliangiaceae. Conclusion: Applying organic amendments improved plant performance and maintained soil health, contributing to more sustainable crop production. Nevertheless, long-term field studies are recommended to verify the findings of this short-term experiment.