Influência do hidrochar sobre a comunidade microbiana de um solo da Caatinga afetado pela Desertificação

Abstract

The application of biochar can minimize the effects of soil degradation in the Caatinga, but its effects on the diversity of the microbiome of these soils remain little explored. The aim was to evaluate the effect of applying cashew bagasse hydrochar, with or without the inoculation of plant growth-promoting microorganisms, on soil chemical attributes, plant growth and microbiological diversity/activity in a degraded Caatinga soil. The soil was collected in the municipality of Irauçuba-CE and the experiment was set up in a protected environment, with the following treatments: (1) hydrochar (with or without) and (2) inoculation (CONT: control, AMF: Gigaspora margarita, PGPB: Bacillus aryabhattai and CO: co-inoculation), with 4 replications. Sabia (90 days) and maize (55 days) were grown, and the pots received a dose of 10 Mg ha-1 of hydrochar. The number of leaves (NL), plant height (PH), stem diameter (SD), mass of dry matter of the aerial part (MDMAP) and roots (MDMR) were quantified. The enzymatic activities of ³-glucosidase, acid phosphatase and urease and their stoichiometric ratios were determined. Total DNA was extracted from the soil cultivated with sabia and the 16S rRNA gene was sequenced using the Illumina NextSeq platform. The structure of the microbial community was demonstrated through the abundance of phyla and genera, alpha diversity (richness of ASVs) and Shannon's diversity index. Beta diversity was plotted in a principal coordinates analysis. In the soil cultivated with sabia, all the hydrochar treatments reduced pH and increased height, MDMAP, C, N, K+ and H+Al content, ³-glucosidase activity, acid phosphatase activity, vector length and angle. The most abundant phyla were Actinobacteria, Proteobacteria, Acidobacteria and Chloroflexi and the genera were Rubrobacter, Streptomyces, Gaiella, Sphingomonas and Nocardioides, with no significant differences. Richness and diversity indices were reduced by the application of hydrochar, but this effect was alleviated by co-inoculation. In soil cultivated with maize, hydrochar treatments increased stem diameter, C, K+, H+Al content and sum of bases. MDMR was increased by treatment with PGPB. Only urease activity was higher in the CO treatment without hydrochar. The addition of hydrochar improved plant growth, soil chemical attributes and the enzymatic activity of ³-glucosidase and acid phosphatase; however, it reduced the richness and diversity of prokaryotic organisms in the soil.