Sewage sludge application alters the composition and co-occurrence pattern of the soil bacterial community in southern China forestlands

• Published in: Applied soil ecology : a section of Agriculture, ecosystems & environment ecosystems & environment, 2021-01, Vol.157, p.103744, Article 103744
• Main Authors: Zhao, Qian, Chu, Shuangshuang, He, Dan, Wu, Daoming, Mo, Qifeng, Zeng, Shucai
• Format: Article
• Language: English
• Subjects: Amplicon sequencing; Heavy metal; Network analysis; Plant litter; Soil bacterial community; Subtropical forest
• ISSN: 0929-1393; 1873-0272
• DOI: 10.1016/j.apsoil.2020.103744

Application of sewage sludge to forested land has been regarded as a promising method for sewage sludge disposal, because it can improve soil fertility and productivity. It is also likely to alter the soil nutrient cycle, which is mainly mediated by soil microorganisms. However, how the soil bacterial community responds to the application of sewage sludge in subtropical planted forests is poorly understood. Unlike farmland soil, forestland soil is covered with leaf litter, which might influence the effects of sewage sludge on the soil bacterial community. In this study, we investigated the effects of sewage sludge application (30 t/ha) on the soil bacterial community at 0–10 cm depth in three forest plantations (Eucalyptus urophylla, Pinus elliottii, and Schima superba) in southern China. The treatments included sewage sludge addition (treatment S), sewage sludge addition and leaf litter removal (treatment SLR), and a control (CK). The composition of the soil bacterial community differed in the three forest plantations and was affected by treatment S, but the effects of treatment S were not greatly altered by litter removal in the three forest plantations. At the community level, the composition of the soil bacterial community was significantly related to soil pH, available phosphorus (P) and potassium (K), and cadmium (Cd). At the phylum level, the relative abundance of Actinobacteria, Bacteroidetes, and Chloroflexi was increased by treatments S and SLR, while that of Acidobacteria, Proteobacteria, and Verrucomicrobia was decreased. The changes in the abundance of these bacteria were significantly related to the increase in the contents of available nutrients and heavy metals. Sewage sludge application resulted in an increased number of positive interactions among bacterial taxa, lower modularity, and higher connectivity, which indicated an unstable bacterial community. Changes in the composition, co-occurrence pattern, and keystone taxa of the bacterial community might reflect adaptation to sewage sludge application. •The bacterial community composition shifted with sewage sludge (SS) in all plantation types.•No interaction effects were observed between leaf litters and sewage sludge on soil bacterial community.•Members of Bacteroidetes, Actinobacteria, and Chloroflexi significantly increased with SS amended.•The soil bacterial community became unstable under SS amended.•Members of α-/γ-Proteobacteria and Actinobacteria acted as keystone taxa with SS ame