Fig. 4

Effect of mulching and inoculation on the bacterial biodiversity of soil. The soil sampling used for the analysis was carried out at the end of the experiment in September 2021. (a) Bacterial alpha diversity estimated by Shannon’s diversity index. (b) Bacterial beta diversity was estimated by calculating the mean Bray–Curtis dissimilarity index between pairs of samples within each treatment. (c) Venn diagram showing the number of bacterial genera present in more than one sample in each treatment. The crossover zone indicates the bacterial genera crossed in different datasets. Mulching, mulched treatments; non-mulching, non-mulched control treatments; SM700 and SM199, treatments inoculated with Azotobacter strains SM700 and SM199, respectively; non-inoculated, non-inoculated control treatments. Asterisk indicates significant differences for p < 0.05 with respect to the corresponding control (non-mulching control or the non-inoculated control) according to the PERMANOVA test or the ANOVA pair-wise test