Lima A. V. auteur aut IRD da Costa D. P. auteur aut IRD Duda G. P. auteur aut IRD de Barros J. A. auteur aut IRD Santos R. D. auteur aut IRD da Mota S. E. O. auteur aut IRD Lima J. R. D. auteur aut IRD da Silva V. P. auteur aut IRD Lopes M. H. L. auteur aut IRD Hammecker Claude auteur aut IRD Pereira A. P. D. auteur aut IRD Mendes L. W. auteur aut IRD Araujo A. S. F. auteur aut IRD de Medeiros E. V. auteur aut IRD text journalArticle eng text/pdf born digital access Purpose This study evaluated how poultry manure-derived biochar influences the structure, diversity, and co-occurrence networks of soil bacterial communities in nutrient-poor tropical sandy soils. We examined the trade-off between improved soil fertility and potential simplification of microbial networks, testing the hypothesis that high biochar rates would enhance nutrient availability but reduce microbial complexity and diversity. Methods A field experiment was conducted over two years in sandy soils of northeastern Brazil, applying poultry biochar. We used six treatments: (a) control (no amendments), (b) low-rate biochar (Bio_10t = 10 t ha(-1)), (c) high-rate biochar (Bio_40t = 40 t ha(-1)), (d) chicken manure (E.Av = 5 t ha(-1)), (e) synthetic mineral fertilizer (Mineral = NPK), and (f) poultry manure (C.Av = 10 t ha(-1)). Soil chemical properties were assessed, and bacterial communities were analyzed using 16 S rRNA gene sequencing. Network analyses were performed using SparCC and NetCoMi, and multivariate statistics determined key environmental drivers. Results High biochar inputs increased organic C, P, and K levels, leading to a distinct shift in microbial community structure. However, this nutrient enrichment reduced amplicon sequence variants richness by 22.4% (from 3,250 to 2,521) and Shannon diversity by 3.6% (from 7.16 to 6.90) relative to the control. Network analysis showed substantial simplification of microbial interactions: the control treatment had 3,116 co-occurrence edges, which fell to 1,423 under low biochar (Bio_10t) and 1,849 under high biochar (Bio_40t)-reductions of 54% and 40%, respectively. Conclusions Our findings underscore a trade-off: while poultry biochar effectively enhances soil fertility, excessive application may disrupt microbial diversity and interaction networks, potentially compromising long-term soil resilience. These results highlight the need to optimize biochar rates to balance immediate fertility gains with preservation of microbial ecological stability in fragile sandy soils. [GRAPHICS] . specialized Biocarbon Phaseolus vulgaris Soil microbiome Organic amendments Co-occurrence networks Microbial diversity BRESIL 076 068 074 [Early access] [12 p.] 2026 0718-9508 https://www.documentation.ird.fr/hor/fdi:010096330 10.1007/s42729-026-03005-1 0718-9508 [F B010096330] https://www.documentation.ird.fr/hor/fdi:010096330 https://www.documentation.ird.fr/intranet/publi/2026-03/010096330.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2026-03-11 2026-03-30 fdi:010096330 fre