Wastewater reuse for irrigation has become an important practice in many countries in the context of global water scarcity. However, knowledge about the potential soil impact of reusing treated fish-processing (TFP) effluents for irrigation is still limited. The aim of this study was to investigate the response of the soil prokaryotic community in general, and the nitrifying taxa in particular, to TFP-effluent irrigation. We analyzed the impacts of irrigation with two effluent dilutions (EF1 and EF2, with electrical conductivities of 2.7 and 6 mS cm⁻¹, respectively) or water (W) as a control on soil chemical properties, dehydrogenase and nitrifying activities, amoA gene abundances of ammonia-oxidizing bacteria (AOB) and archaea (AOA), and soil prokaryotic community structure and diversity. At the end of the irrigation experiment, soil ammonium, nitrate plus nitrite, dehydrogenase and nitrifying activities, soil electrical conductivity (EC), and sodium adsorption ratio (SAR) were significantly higher in TFP-irrigated treatments than in water irrigated controls. Prokaryotic richness and diversity indices followed the pattern W > EF1 > EF2, and negatively correlated with soil EC, SAR, ammonium, nitrate plus nitrite, and total N concentrations. In particular, EF2-irrigation stimulated soil copiotrophic bacteria (e.g. Proteobacteria and Bacteroidetes) to the detriment of oligotrophic members such as Acidobacteria. TFP-effluent irrigation also influenced the relative abundance of the amoA gene of AOB but not that of AOA; and the composition of nitrifying taxa, by inducing a significant increase in OTUs whose closest cultured matches were ‘Candidatus Nitrosocosmicus franklandus’ and Nitrosospira briensis Nsp10. Overall, irrigation with the more diluted effluent (classified as slight to moderate degree of restriction by local regulations) induced a reduction of soil prokaryotic diversity, whereas the less diluted effluent (severe irrigation restriction) promoted the greatest changes in the prokaryotic community due to the increase in soil salinity and N content.

在全球水资源短缺的背景下，废水再利用用于灌溉已成为许多国家的重要实践。然而，关于再利用处理过的鱼类加工 (TFP) 流出物用于灌溉的潜在土壤影响的知识仍然有限。本研究的目的是调查土壤原核生物群落，特别是硝化类群对 TFP 废水灌溉的响应。我们分析了灌溉用两种流出物稀释液（EF1 和 EF2，电导率分别为 2.7 和 6 mS cm ^-1）或水 (W) 对土壤化学性质、脱氢酶和硝化活性amoA的控制的影响氨氧化细菌（AOB）和古细菌（AOA）的基因丰度，以及土壤原核生物群落结构和多样性。在灌溉试验结束时，TFP 灌溉处理的土壤铵、硝酸盐加亚硝酸盐、脱氢酶和硝化活性、土壤电导率 (EC) 和钠吸附率 (SAR) 显着高于水灌溉对照。原核生物丰富度和多样性指数遵循W > EF1 > EF2的规律，与土壤EC、SAR、铵态氮、硝酸盐加亚硝酸盐和总N浓度呈负相关。特别是，EF2 灌溉刺激了土壤富营养性细菌（例如变形菌和拟杆菌），从而损害了嗜酸菌等贫营养性成员。AOB的基因，但不是AOA的基因；和硝化类群的组成，通过诱导 OTU 显着增加，其最接近的培养匹配是' Candidatus Nitrosocosmicus franklandus'和Nitrosospira briensis Nsp10。总体而言，用稀释程度更高的出水灌溉（当地法规归类为轻度至中度限制）导致土壤原核生物多样性减少，而稀释程度更低的出水（严重灌溉限制）促进了原核生物群落的最大变化，因为土壤盐分和氮含量增加。