Straw Mulching and Nitrogen Fertilization Affect Diazotroph Communities in Wheat Rhizosphere

Abstract

Diazotrophs that carry out the biological fixation of atmospheric dinitrogen (N2) replenish biologically available nitrogen (N) in soil and are influenced by the input of inorganic and organic substrates. To date, little is known about the effects of combined organic substrate addition and N fertilization on the diazotroph community composition and structure in purple soils. We investigated the effects of N fertilization and straw mulching on diazotroph communities by quantifying and sequencing the nifH gene in wheat rhizosphere. The abundance and richness of diazotrophs were greater the higher the fertilization level in the mulched treatments, whereas in the nonmulched treatments (NSMs), richness was lowest with the highest N fertilization level. The abundance and α-diversity of diazotrophs correlated with most of the soil properties but not with pH. At the genus level, the relative abundances of Azospirillum, Bacillus, and Geobacter were higher in the NSMs and those of Pseudacidovorax, Skermanella, Azospira, Paraburkholderia, Azotobacter, Desulfovibrio, Klebsiella, and Pelomonas in the mulched treatments. The differences in community composition between the mulched and the NSMs were associated with differences in soil temperature and soil organic carbon and available potassium contents and C:N ratio. Overall, straw mulching and N fertilization were associated with changes in diazotroph community composition and higher abundance of nifH gene in alkaline purple soils.

Soil depths and microhabitats shape soil and root-associated bacterial and archaeal communities more than crop rotation in wheat

“…We efficiently differentiated RH and RP using a combination of approaches (Lucas et al, 2018). Upon analyzing microorganisms commonly associated with the wheat rhizosphere (Chen et al, 2019;Chen et al, 2021b;Elvia et al, 2021;Kavamura et al, 2021;Prudence et al, 2021), we observed that certain microorganisms were indeed highly abundant on the rhizoplane. It is likely that the greater abundance of Proteobacteria in the rhizoplane is due to increased root accessibility to nutrients (Ho et al, 2017;Ling et al, 2022).…”

Soil-plant-microbiota interactions to enhance plant growth

“…More than the amount of C, the quality of the soil organic matter seems to be more determinant to nitrogen fixation. Several authors report a positive correlation between soil C:N ratio and the diversity and activity of the diazotrophic community, so that higher C:N values could result in a competitive advantage for free-living diazotrophs (Mirza et al, 2014;Yang et al, 2019;Chen et al, 2021;Dai et al, 2021b).…”

“…Rev Bras Cienc Solo 2022;46:e0210098 Application of fertilizers, either chemical or organic, can favor nitrogen fixation by improving soil fertility, yet the response to nutrients availability is highly variable. Although nitrogen availability can have stimulatory effects on diazotrophic diversity (Poly et al, 2001), most of the recent studies evidence its negative effects on nitrogen fixation and diazotrophic abundance (Reardon et al, 2014;Zheng et al, 2019;Xiao et al, 2020;Chen et al, 2021;Dai et al, 2021b). Potassium can have negative (Hsu and Buckley, 2009), little or no effect (Tang et al, 2017), while phosphorus, in general, has stimulatory effects over nitrogen fixation (Tang et al, 2017;Zheng et al, 2019;Zheng et al, 2019).…”

“…Organic fertilizers and crop residue management can also affect the nitrogen-fixation process in variable ways. Yang et al (2019) concluded that soil incorporation of rice straw repressed nifH gene abundance, but increased α-diversity; while Chen et al (2021) found that wheat mulch, along with chemical fertilization, increased the abundance and richness of diazotrophs. Liao et al (2018) found that the combined use of chicken manure and chemical fertilizers can improve the activity of the diazotrophic community.…”

Nodule-associated diazotrophic community succession is driven by developmental phases combined with microhabitat of Sophora davidii

“…Among them, soil harbors the most diverse diazotrophic microbial communities, with Proteobacteria and Cyanobacteria as the most abundant members ( Gaby and Buckley, 2011 ). Many factors have been reported to affect the structure of diazotrophic community, such as temperature ( Feng et al, 2019 ) and precipitation ( Yeager et al, 2012 ), plant species richness ( Sheng et al, 2019 ), soil type and pH ( Zhang et al, 2018 ; Han et al, 2019 ), agricultural activities such as nitrogen fertilization ( Chen et al, 2021 ). In addition, some seasonal factors and growth cycle of the host plant ( Pereira et al, 2013 ) also regulated the diazotrophic communities that caused a clear seasonal succession of these microbes in some environments ( Zilius et al, 2021 ).…”