Effects of nitrogen reduction combined with bio-organic fertilizer on soil bacterial community diversity of red raspberry orchard

Abstract

Understanding soil bacterial diversity under nitrogen reduction is necessary for the crucial role in soil nitrogen cycling. However, the effects of combined fertilization on soil chemical properties, microbial community structure, and yield are unknown. This study was conducted to investigate the effect of nitrogen fertilizer reduction with bio-organic fertilizer on soil bacterial community diversity of red raspberry orchard. Six treatments were set in this study: NF-100%, NF-75%, NF-50%, NF-25% and CF, no nitrogen fertilizer and bio-organic fertilizer for CK. The bacterial community structures of soil were analyzed by 16S rRNA gene amplification high-throughput sequencing technology. Nitrogen fertilizer reduction with bio-organic fertilizer increased soil organic matter (SOM), total nitrogen (TN), alkali-hydrolyzable nitrogen (AN), available phosphorus (AP), available potassium (AK), and reduced soil pH. NF-50% and NF-25% treatments increased the yield of red raspberry. Nitrogen reduction combined with bio-organic fertilizer increased the relative abundance of copiotrophic bacteria and decreased the relative abundance of oligotrophic bacteria. The increase in copiotrophic bacteria in the soil of red raspberry orchard could indicate an increase in soil nutrient availability, which have positive implications for soil fertility and production. However, nitrogen fertilizer reduction with bio-organic fertilizer altered the abundance and diversity of soil bacteria, which was reduced compared to CF treatments. The PCoA analysis of the soil bacterial community showed that the community structure of NF-25% treatment was more different from other treatments, indicating that the fertilization method changed the community structure of soil bacteria. The results of a redundancy analysis showed that SOM, pH, AN, TN, and AP were the main factors affecting the microbial community structure. Overall, the reduction of nitrogen fertilizer with bio-organic fertilizer significantly increased the soil nutrient content, reduced the relative abundance and diversity of soil bacteria, increased the relative abundance of beneficial bacteria in the soil, changed the bacterial community structure of soil, increased production and created suitable soil conditions for the red raspberry growth.

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“…The obtained PCR amplicons were purified with Vazyme VAHTSTM DNA Clean Beads (Vazyme, Nanjing, China) and subsequently quantified via the Quant-iT PicoGreen dsDNA Assay Kit (Invitrogen, Carlsbad, CA, USA). After the individual quantification procedure, amplicons were pooled in equal amounts, and pair-end 2 × 250 bp sequencing was carried out at an Illlumina NovaSeq platform using NovaSeq 6000 SP Reagent Kit (500 cycles) (Yuan et al, 2023). QIIME2 (2019.4) software was used to call qiime cutadapt trimpairs, so as to remove the primer fragments and cast away the sequences of the unmatched primers.…”