Background and aims

A-HA (artificial humic acid) play essential roles to improve soil organic matter in agricultural soil, however, the relative mechanistic effects on soil phosphorus (P) transformation and availability resulting from stimulation of microbial activities and changes in microbial communities remain uncertain. This study investigated the responses of microbial communities in the rhizosphere, bulk soils, and unplanted soil with the combined application of A-HA and phosphate fertilizer to better understand the mechanisms by which A-HA affects P cycling.

Methods

Physical and chemical analyses, along with metagenomic methods, were employed to determine phosphorus availability and fractions, as well as to measure soil microbial diversity and the relative abundance of microbial P-cycling genes in bulk soil, rhizosphere soil, and unplanted soil subjected to varying levels of phosphorus fertilizer.

Results

The findings demonstrated that application of A-HA and phosphate fertilizers directly increased soil Olsen P and unstable P levels and indirectly altered microorganism functional genes involved in soil P cycling. More interestingly, 28 macrogenomic assembled genomes (MAGs) were reconstructed, all of which contained P cycle-related genes with copy numbers ranging from 1 to 8. In addition, we evaluated the correlation among maize biomass, photosynthetic characteristics, plant P uptake, and P utilization efficiency (PUE) and stabilized soil P fractions. A-HA + P0.5 treatment appeared the most promising due to its higher sustainability yield index and agronomic efficiency.

Conclusions

Our results highlight the importance of A-HA in promoting changes in microbial functional genes involved in soil P cycling with different P levels.

中文翻译：

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人工腐植酸通过调节 P 循环微生物群落促进作物生长提高 P 有效性

 背景和目标

A-HA（人工腐植酸）在改善农业土壤中的土壤有机质方面起着重要作用，然而，刺激微生物活动和微生物群落变化对土壤磷 （P） 转化和可用性的相对机制影响仍不确定。本研究调查了根际、块状土壤和未种植土壤中微生物群落对 A-HA 和磷肥联合施用的反应，以更好地了解 A-HA 影响 P 循环的机制。

 方法

采用物理和化学分析以及宏基因组学方法来确定磷的可用性和分数，以及测量土壤微生物多样性和微生物 P 循环基因在散装土壤、根际土壤和未种植的土壤中受到不同水平磷肥的土壤的相对丰度。

 结果

研究结果表明，施用 A-HA 和磷肥直接增加了土壤 Olsen P 和不稳定的 P 水平，并间接改变了参与土壤 P 循环的微生物功能基因。更有趣的是，重建了 28 个宏基因组组装基因组 （MAG），所有这些基因组都包含拷贝数从 1 到 8 的 P 周期相关基因。此外，我们评估了玉米生物量、光合特性、植物磷吸收和磷利用效率 （PUE） 与稳定土壤磷组分之间的相关性。A-HA + P0.5 处理因其较高的可持续性产量指数和农艺效率而显得最有前景。

 结论

我们的研究结果强调了 A-HA 在促进不同 P 水平土壤 P 循环中参与 P 循环的微生物功能基因变化的重要性。