Partial substitution of chemical fertilizers by organic amendments is essential for improving the soil quality without yield loss. Fungi play an important role in soil quality because they decompose organic matter and cycle nutrients in the soil. However, there is limited information regarding the effect of different organic substitution rates (OSRs) on the soil quality and fungal community. This study investigated the relationship between the soil quality index and fungal community in a tea plantation under different OSRs of N, from a single application of synthetic fertilizer (NPK) to 100% N substitution with organic fertilizer (OM100). The OSRs were positively correlated with the soil physicochemical and biological soil quality index (SQI), but only the physicochemical SQI exhibited a significant relationship with tea production. The OSR also shifted the soil fungal community composition. Soil pH, soil organic C (SOC), microbial biomass C (MBC), and available potassium (AK) were the key characteristics that were significantly correlated with the variation of soil fungal community. Network analysis indicated that additional organic substitution can enhance the soil fungal network complexity, which also showed a positive correlation with the SQI. These results confirmed the feasibility of organic substitution for soil quality improvement, and implied that the soil fungal network complexity could be a new indicator for soil quality assessment.

中文翻译：

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有机替代率对长期施肥茶园土壤质量和真菌群落组成的影响

用有机添加物部分替代化肥对于改善土壤质量而不损失产量是必不可少的。真菌对土壤质量起着重要作用，因为它们分解土壤中的有机物质并循环养分。然而，关于不同有机替代率 (OSR) 对土壤质量和真菌群落的影响的信息有限。本研究调查了不同氮 OSR 下茶园土壤质量指数与真菌群落之间的关系，从单次施用合成肥料 (NPK) 到 100% 氮替代有机肥 (OM100)。OSR与土壤理化和生物土壤质量指数（SQI）呈正相关，但只有理化SQI与茶叶产量呈显着相关。OSR 还改变了土壤真菌群落组成。土壤pH值、土壤有机碳（SOC）、微生物生物量碳（MBC）和速效钾（AK）是与土壤真菌群落变化显着相关的关键特征。网络分析表明，额外的有机替代可以增强土壤真菌网络的复杂性，这也与 SQI 呈正相关。这些结果证实了有机替代改善土壤质量的可行性，并暗示土壤真菌网络的复杂性可以成为土壤质量评估的新指标。有效钾（AK）是与土壤真菌群落变异显着相关的关键特征。网络分析表明，额外的有机替代可以增强土壤真菌网络的复杂性，这也与 SQI 呈正相关。这些结果证实了有机替代改善土壤质量的可行性，并暗示土壤真菌网络的复杂性可以成为土壤质量评估的新指标。有效钾（AK）是与土壤真菌群落变异显着相关的关键特征。网络分析表明，额外的有机替代可以增强土壤真菌网络的复杂性，这也与 SQI 呈正相关。这些结果证实了有机替代改善土壤质量的可行性，并暗示土壤真菌网络的复杂性可以成为土壤质量评估的新指标。