Soil carbon-rich organic amendments (biochar, humic substances) may improve the quality and fertility of arable soil. Their co-application can additively enhance the beneficial effect on soil. Hypothetically, the pre-treatment of biochar, by aging via soaking in a solution of commercially available humic substances, could result in synergism, which may exceed the benefit from simple co-application of both amendments to the soil. Therefore, the aim of this study was to investigate the impact of biochar, humic substances, the combination of both, and the impact of biochar aged by humic substances solution on soil microbial activities and plant growth in a short-term pot experiment with lettuce. The aging of biochar decreased the C:N ratio as compared to non-activated biochar. The co-application of biochar and humic substances into the soil resulted in the highest microbial biomass carbon and respiration activity. The majority of enzyme activities (β-glucosidase, arylsulfatase, N-acetyl-β-d-glucosaminidase, phosphatase) were the highest in humic substances-amended soil. The application of humic substances and biochar with humic substances seemed to stimulate microbial growth and activity followed by the competition of microflora for nutrients with plants, whereas the aged biochar behaved differently. The plants treated by aged biochar achieved the highest values of dry aboveground and root biomass of all variants. However, the assumed rapid uptake of nutrients by plants resulted in lower nutrient availability for microflora, and a decline in microbial viability. Based on this study, the positive effect of co-applied humic substances and biochar on soil fertility, quality, and health can be concluded. The usability of biochar aging by humic solution requires further study.

中文翻译：

---

评估腐殖质老化的生物炭增强植物生长和土壤生物活性的潜力

土壤富含碳的有机改良剂（生物炭、腐殖质）可以提高耕地的质量和肥力。它们的共同应用可以增加对土壤的有益影响。假设生物炭的预处理，通过浸泡在市售腐殖质溶液中进行老化，可能会产生协同作用，这可能会超过两种改良剂在土壤中的简单共同应用所带来的好处。因此，本研究的目的是在短期生菜盆栽试验中研究生物炭、腐殖质、两者的组合以及腐殖质溶液老化的生物炭对土壤微生物活动和植物生长的影响。与未活化的生物炭相比，生物炭的老化降低了 C:N 比。生物炭和腐殖质在土壤中的共同应用导致最高的微生物生物量碳和呼吸活性。大多数酶活性（β-葡萄糖苷酶、芳基硫酸酯酶、N-乙酰-β-d-氨基葡萄糖苷酶、磷酸酶）在腐殖质改良土壤中最高。腐殖质和含有腐殖质的生物炭的应用似乎刺激了微生物的生长和活动，随后微生物群落与植物竞争养分，而老化的生物炭表现不同。用陈年生物炭处理的植物达到了所有变体的最高干燥地上生物量和根生物量值。然而，假设植物对养分的快速吸收导致微生物群落的养分利用率降低，微生物活力下降。基于这项研究，可以得出共同施用腐殖质和生物炭对土壤肥力、质量和健康的积极影响。腐殖质溶液老化生物炭的可用性需要进一步研究。