Response of bacterial community composition and co-occurrence network to straw and straw biochar incorporation

Abstract

Microbial decomposition plays a crucial role in the incorporation of straw and straw biochar (SSB) into soil. Lime concretion black soil (LCBS) is a typical low-medium crop yield soil, and it is also one of the main soil types for grain production in China. However, the link between SSB additions and soil bacterial communities in LCBS remains unclear. This study explored the effects of SSB incorporation on bacterial community composition, structure and co-occurrence network patterns at different soil depths and maize growth stages. The results showed that soil PH, soil organic matter and total nitrogen significantly affected the seasonality and stratification of the soil bacterial community. The composition and diversity of bacterial communities were significantly affected by growth period and treatment rather than soil depth. Specifically, the bacterial community diversity increased significantly with crop growth at 0–20 cm, decreased the relative abundance of Actinobacteria, and increased the relative abundance of Proteobacteria and Acidobacteria. SF (straw with fertilizer) and BF (straw biochar with fertilizer) treatments decreased bacterial community diversity. Co-occurrence networks are more complex in BF, S (straw), and SF treatments, and the number of edge network patterns is increased by 92.5, 40, and 60% at the maturity stage compared with F (fertilizer) treatment, respectively. Moreover, the positive effect of straw biochar on the bacterial network pattern increased with time, while the effect of straw weakened. Notably, we found that rare species inside keystone taxa (Gemmatimonadetes and Nitrospirae) play an indispensable role in maintaining bacterial network construction in LCBS. This study offers a comprehensive understanding of the response of soil bacterial communities to SSB addition in LCBS areas, and provides a reference for further improvement of LCBS productivity.

Microbial community and network differently reshaped by crushed straw or biochar incorporation and associated with nitrogen fertilizer level

“…As identified by the network analysis, SD network is more complex and robustly stable than BC, as reflected by the high number of edge, average degree, graphic density, and average clustering coefficient (Figure 4). This result was partly consistent with the observation of Du, Zhang, et al (2022), who found that straw had positive effect on the bacterial network pattern. The interactions of soil microbial communities became strong in response to straw return, which demonstrates that the degradation of complex organic matter in SD soil may require a variety of microorganisms to work together (Yang, Bao, et al, 2022).…”

“…The RA of Sphingomonas in this study was affected by SRMs and associated with NFLs, which was significantly increased by BC at the N60 level but was significantly decreased by SD at the N0 level (Table S2). A previous study also suggested that the effect of straw return on the RA of Proteobacteria was related to the nitrogen level (Du, Zhang, et al, 2022). The sufficient air and organic nutrient conditions provided by BC might be responsible for the increase in Sphingomonas (Li, Song, et al, 2022; Li, Zheng, et al, 2022).…”

“…These results are consistent with observation of Yang, Muhammad, et al (2022), who found that straw return improves soil bacterial diversity and richness. The development of bacterial diversity under SD could be explained by the release of diverse nutrients and soluble organic matter during the decomposition of crop straw, providing space, and influencing other soil environmental factors, which are beneficial to the proliferation and growth of microorganisms and produce stable and healthy soil ecosystem (Du, Zhang, et al, 2022; Tang et al, 2021). Different from fungal richness, the fungal Shannon index was significantly decreased by SD at reduced NFLs while remained stable in BC at each NFL (Table 1).…”

“…The underlying mechanism of soil microbial responses to straw returning should cover microbial species interactions and potential ecological functions (Cui et al, 2022;Jiang et al, 2017;Morriën et al, 2017). The enhanced complexity in bacterial network caused by straw returning has been previously reported (Du, Zhang, et al, 2022;Yang, Bao, et al, 2022). However, whether and how cooccurrence network pattern of bacteria and fungi respond to different SRMs at varying NF levels (NFLs) in the black soils remain unclear.…”

Co-occurrence network of soil bacterial communities in agricultural fields in central Yunnan under different fertilization treatments

“…During the fallow period (December), the soil bacterial Shannon index, Chao index, and Ace index were signi cantly higher under OM, MNPK, and ST treatments (OM > MNPK > ST). This may be a result of nutrients and soluble organic matter released from decomposed manure and straw that were not fully absorbed and utilized by roasted tobacco, with the accumulated nutrients stimulating microbial growth and increasing diversity (Ge et al 2021;Du et al 2022). In our study, no signi cant differences were observed in bacterial α-diversity..On the other hand,t ANOSIM analysis revealed that different sampling periods signi cantly affected bacterial β-diversity.…”