活性污泥萃取液的安全性及对水稻苗期生长和土壤环境的影响
Safety of Activated sludge extract and its effect on rice seedling growth and soil environment
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摘要: 【目的】探讨活性污泥萃取液的安全性及部分替代化肥对水稻幼苗生长、土壤理化性质及土壤微生物群落结构的影响,为活性污泥萃取液安全性及作为有机肥农用提供理论基础。【方法】以水稻南粳9108为实验材料,开展活性污泥萃取液安全性试验及不同配施量处理试验(CK,空白对照;CF,常规施肥对照;LMF,低量活性污泥萃取液配施化肥;HMF,高量活性污泥萃取液配施化肥;MF,全量活性污泥萃取液),研究萃取液对水稻苗期的生长性状、土壤理化性质、土壤微生物群落结构的影响。【结果】活性污泥萃取液中的重金属元素含 量符合安全施用标准,且适宜浓度的活性污泥萃取液浸种可促进水稻种子萌发。根箱试验结果表明,施用活性污泥萃取液可促进水稻幼苗株高、茎宽、叶面积、地上部生物量与地下部生物量等生长指标的增加。配施活性污泥萃取液与常规施肥相比可显著提高土壤pH 2.8%-13.8%,并减少14.3%-66.3%的土壤盐分,增加土壤可溶性有机碳含量最高可达68.0%。通过对不同施肥处理土壤的高通量测序分析,结果显示丰度前十的细菌门类在各处理土壤中均有分布,不同施肥措施改变了细菌分布比例,且对近根际土壤细菌群落结构影响较大。施用活性污泥萃取液后,与碳循环相关门类菌群显著增加,如变形菌门、放线菌门、疣微菌门等;常见于胁迫环境的厚壁菌门显著减少。【结论】活性污泥萃取液的重金属含量低于国家氨基酸水溶肥料重金属标准,且施用适宜浓度的活性污泥萃取液可促进种子萌发,活性污泥萃取液的农用安全性得以保障。施用高量活性污泥萃取液能显著促进水稻幼苗生长、改善土壤理化性质,优化土壤菌群结构,可相比于有机肥施用效能。在实际水稻生产过程中可优先采用减氮30%化肥配施高量活性污泥萃取液,以促进水稻生长。Abstract: 【Objective】The safety of Activated sludge extract and the effects of partial substitution of chemical fertilizers on rice seedling growth, soil physicochemical properties and soil bacterial community structure were discussed to provide a theoretical basis for the safety of activated sludge extract and its application as organic fertilizer in agriculture.【Method】Taking rice Nangeng 9108 as the experimental material, a safety assessment experiment of activated sludge extract and an agriculture application experiment with different dosages was established (CK: blank control; CF: conventional fertilization control; LMF: low-amount activated sludge extract with fertilizer; HMF: high-amount activated sludge extract with fertilizer; MF: activated sludge extract applied only). The effects of different treatments on the growth characteristics, chlorophyll content of rice seedlings, soil physicochemical properties, soil bacterial community structure were studied. 【Result】 The content of heavy metal elements in the activated sludge extract could meet the safe application standard of organic fertilizer and soaking seeds with low-concentration activated sludge extract could promote the germination of seeds. The results of the root box experiment showed that compared with the control and conventional fertilization control group, the application of activated sludge extract could promote the growth of rice seedlings, such as plant height, stem width, leaf area, and plant biomass. Compared with conventional fertilization, the combined application of activated sludge extract could significantly increase soil pH by 2.8%-13.8%, reduce soil salinity by 14.3%-66.3%, and increase soil soluble organic carbon content by up to 68.0%. High throughput sequencing analysis of soils with different fertilization treatments showed that the top ten phyla of abundance were distributed in all treatments, and the applied activated sludge extract had a significantly impact on soil bacterial community structure. After applying activated sludge extract, the flora of the phyla related to carbon cycle increased significantly, such as Proteobacteria, Actinomycetes, Verrucomicrobia, etc.; Firmicutes, which are common in stressful environments, were significantly reduced.【Conclusion】The application of activated sludge extract could promote the germination of rice seeds, and the agricultural safety of the activated sludge extract can be guaranteed. At the same time, the application of a high amount of activated sludge extract could significantly improve the growth characteristics of rice seedlings, improve soil physical and chemical properties, and optimize the structure of soil bacterial, which is comparable to the efficiency of organic fertilizer application. In practice, the treatment of reducing nitrogen fertilizer application rate by 30% nitrogen by high amount of activated sludge extract could be preferred.
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