Soil suppressiveness which is the natural ability of soil to support optimal plant growth and health is the resultant of multiple soil microbial components; which implies many difficulties when estimating this soil condition. Microbial benefits for plant health from repeated digestate applications were assessed in three experimental sites surrounding anaerobic biogas plants in an intensively cultivated area of northern Italy. A 2-yr trial was performed in 2017 and 2018 by performing an in-pot plant growth assay, using soil samples taken from two fields for each experimental site, of which one had been repeatedly amended with anaerobic biogas digestate and the other had not. These fields were similar in management and crop sequences (maize was the recurrent crop) for the last 10 yr. Plant growth response in the bioassay was expressed as plant biomass production, root colonization frequency by soil-borne fungi were estimated to evaluate the impact of soil-borne pathogens on plant growth, abundance of Pseudomonas and actinomycetes populations in rhizosphere were estimated as beneficial soil microbial indicators. Repeated soil amendment with digestate increased significantly soil capacity to support plant biomass production as compared to unamended control in both the years. Findings supported evidence that this increase was principally attributable to a higher natural ability of digestate-amended soils to reduce root infection by saprophytic soil-borne pathogens whose inoculum was increased by the recurrent maize cultivation. Pseudomonas and actinomycetes were always more abundant in digestate-amended soils suggesting that both these large bacterial groups were involved in the increase of their natural capacity to control soil-borne pathogens (soil suppressiveness).

中文翻译：

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用沼气消化物反复进行土壤改良可以增加土壤对农田中非特异性土传病原体的抑制能力吗？

土壤抑制性是土壤支持最佳植物生长和健康的天然能力，是多种土壤微生物成分的结果；这意味着在估计这种土壤条件时存在许多困难。在意大利北部一个集约化耕作地区的厌氧沼气厂周围的三个实验地点评估了重复使用消化物对植物健康的微生物益处。2017 年和 2018 年进行了一项为期 2 年的试验，通过进行盆内植物生长试验，使用从每个试验地点的两个田地采集的土壤样本，其中一个已经用厌氧沼气消化物反复修正，另一个没有。这些田地在过去 10 年的管理和作物序列（玉米是经常性作物）相似。假单胞菌属根际和放线菌种群被估计为有益的土壤微生物指标。与两年中未修正的对照相比，用消化物进行的重复土壤改良显着增加了支持植物生物量生产的土壤容量。研究结果支持的证据表明，这种增加主要归因于消化物改良土壤的更高自然能力，以减少腐生土传病原体的根部感染，这些病原体的接种量因玉米反复种植而增加。假单胞菌属和放线菌在消化物改良的土壤中总是更丰富，这表明这两个大型细菌群都参与了增加它们控制土壤传播病原体的自然能力（土壤抑制性）。