The Dry Chaco region is a vast plain that extends throughout north-western Argentina. This region concentrates about 13% of the total Argentine cattle national stock. Beef cattle systems in the north-west of Argentina are highly varied including extensive pastoral systems, silvopastoral systems and intensive grazing systems. Little is known about the impact of these systems on microbial biodiversity and soil quality in this region. This study describes the relationship between soil parameters (FDA, MBC, SOC, CFU, pH, TN and MR) and bacterial communities in silvopastoral systems (SPS) of the Argentine Dry Chaco region. The bacterial composition, evaluated through Illumina MiSeq sequencing of ribosomal 16S amplicons, differed between SPS and pastoral systems, being also influenced by Leucaena and Prosopis tree species. Higher diversity of bacterial populations was detected in SPS with Prosopis. The phylum Firmicutes and Bacilli class were the most abundant in all the treatments. As indicated by Mantel tests, changes in soil bacteria community were related to soil parameters (e.g. SOC and pH). SPSs are viable alternatives for improving soil quality, supported by a significant increase in microbial biomass and activity in comparison with pastoral systems. Furthermore, the different livestock systems strongly affected microbiomes. Overall, the results of the present study suggest that soil bacterial populations are involved in nutrient cycling processes in SPSs of the Argentine Dry Chaco. Further, the composition of soil bacterial communities was related to the analysed soil parameters and tree species.

中文翻译：

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阿根廷干查科的林牧系统：对土壤化学参数和细菌群落的影响

干查科地区是一片广阔的平原，贯穿阿根廷西北部。该地区集中了阿根廷全国牛总存量的 13%。阿根廷西北部的肉牛系统多种多样，包括粗放牧系统、林牧系统和集约放牧系统。关于这些系统对该地区微生物生物多样性和土壤质量的影响知之甚少。本研究描述了土壤参数（FDA、MBC、SOC、CFU、pH、TN 和 MR）与阿根廷干查科地区林牧系统 (SPS) 中细菌群落之间的关系。通过核糖体 16S 扩增子的 Illumina MiSeq 测序评估的细菌组成在 SPS 和牧区系统之间有所不同，也受银合欢属和Prosopis树种。在具有Prosopis 的SPS 中检测到更高的细菌种群多样性. 厚壁菌门和杆菌门在所有处理中含量最高。Mantel 测试表明，土壤细菌群落的变化与土壤参数（例如 SOC 和 pH 值）有关。SPS 是改善土壤质量的可行替代方案，与牧区系统相比，微生物生物量和活性显着增加。此外，不同的牲畜系统强烈影响微生物组。总体而言，本研究的结果表明土壤细菌种群参与了阿根廷干查科 SPS 的养分循环过程。此外，土壤细菌群落的组成与分析的土壤参数和树种有关。