Nitrogen fertilization rates mediate rhizosphere soil carbon emissions of continuous peanut monoculture by altering cellulose-specific microbess

Abstract

IntroductionCrops influence both soil microbial communities and soil organic carbon (SOC) cycling through rhizosphere processes, yet their responses to nitrogen (N) fertilization have not been well investigated under continuous monoculture.MethodsIn this study, rhizosphere soil microbial communities from a 5-year continuous mono-cropped peanut land were examined using Illumina HighSeq sequencing, with an N fertilization gradient that included 0 (N0), 60 (N60), 120 (N120) and 180 (N180) kg hm−2. Soil respiration rate (Rs) and its temperature sensitivity (Q10) were determined, with soil carbon-acquiring enzyme activities assayed.Results and discussionThe obtained results showed that with N fertilization, soil mineral N (Nmin) was highly increased and the soil C/N ratio was decreased; yields were unchanged, but root biomass was stimulated only at N120. The activities of β-1,4-glucosidase and polyphenol oxidase were reduced across application rates, but that of β-1,4-cellobiohydrolase was increased only at N120. Bacterial alpha diversity was unchanged, but fungal richness and diversity were increased at N60 and N120. For bacterial groups, the relative abundance of Acidobacteria was reduced, while those of Alphaproteobacteria and Gammaproteobacteria were increased at N60 and N120. For fungal members, the pathogenic Sordariomycetes was inhibited, but the saprotrophic Agaricomycetes was promoted, regardless of N fertilization rates. RDA identified different factors driving the variations in bacterial (root biomass) and fungal (Nmin) community composition. N fertilization increased Rs slightly at N60 and significantly at N120, mainly through the promotion of cellulose-related microbes, and decreased Rs slightly at N180, likely due to carbon limitation. N fertilization reduced microbial biomass carbon (MBC) at N60, N120 and N180, decreased SOC at N120 and N180, and suppressed dissolved organic carbon (DOC) at N180. In addition, the unchanged Q10 may be a joint result of several mechanisms that counteracted each other. These results are of critical importance for assessing the sustainability of continuously monocultured ecosystems, especially when confronting global climate change.

Soil fungal community is more sensitive than bacterial community to modified materials application in saline–alkali land of Hetao Plain

“…The amplification conditions were as follows: predenaturation at 95°C for 5 min; 25 cycles (denaturation at 95°C for 30 s, annealing at 50°C for 30 s, extension at 72°C for 40 s), and a final extension at 72°C for 7 min. The PCR amplification of the 16S rRNA/ITS genes and the subsequent purification of the products were conducted according to the methods described by Wu et al (2023) . After the PCR analysis, the purified amplicons were then pooled in equimolar concentrations, and eligible libraries were performed using the Illumina NovaSeq sequencing platform at Beijing Bemac Biotechnology Co., Ltd.…”

Nitrogen Addition Promotes the Accumulation of Soil Particulate Organic Carbon in a Subtropical Forest

“…C and N cycles are considered tightly Forests 2024, 15, 619 2 of 11 linked [5,6], so the effect of N deposition on the SOC pool has attracted the attention of the scientific community. Several studies have examined the effects of N addition on SOC and have reported that the SOC pool rises [7], decreases [8], or remains unchanged [9] with N addition. Overall, there is no unified conclusion on the effect of N deposition on SOC.…”

Green manuring increased peanut yields and reduced soil carbon mineralization by optimizing microbial communities

“…Nevertheless, in the case of peanuts, straw is annually removed as a high-quality feedstuff instead of being returned to the eld in China, which is not conducive to SOC sequestration (Zhao et al 2017). In addition, peanut yields and farmland quality have long been seriously compromised by continuous cropping obstacles, which probably led to a decrease in soil quality (Wu et al 2023a). Peanut rotation with GM (e.g., oilseed rape) has been proposed as an effective strategy to overcome continuous cropping obstacles (Xu et al 2023), with the concern of additional production of more CO 2 emissions.…”