Purpose: To understand which environmental factors influence the distribution and ecological functions of bacteria in agricultural soil. Method: A broad range of farmland soils was sampled from 206 locations in Jilin province, China. We used 16S rRNA gene-based Illumina HiSeq sequencing to estimated soil bacterial community structure and functions. Result: The dominant taxa in terms of abundance were found to be, Actinobacteria, Acidobacteria, Gemmatimonadetes, Chloroflexi, and Proteobacteria. Bacterial communities were dominantly affected by soil pH, whereas soil organic carbon did not have a significant influence on bacterial communities. Soil pH was significantly positively correlated with bacterial operational taxonomic unit abundance and soil bacterial α-diversity (P<0.05) spatially rather than with soil nutrients. Bacterial functions were estimated using FAPROTAX, and the relative abundance of anaerobic and aerobic chemoheterotrophs, and nitrifying bacteria was 27.66%, 26.14%, and 6.87%, respectively, of the total bacterial community. Generally, the results indicate that soil pH is more important than nutrients in shaping bacterial communities in agricultural soils, including their ecological functions and biogeographic distribution.

C/BiOBr composite materials were synthesized via a simple one-step solvothermal method, with C derived from biochar, which was prepared from the low-cost straw. The samples were characterized by SEM, XRD, XPS and PL. The 2% C/BiOBr composite material showed a noticeable adsorption and photocatalysis synergistic effect to remove CIP. The adsorption rate and degradation rate were 1.45 times and 1.8 times that of BiOBr. The adsorption kinetics and isotherms of CIP on C/BiOBr were analyzed with the pseudo-second-order kinetic and Langmuir models. The degradation efficiency was 96.8% after 60 min of irradiation. High stability and degradability were still maintained after four cycles. The Bi–O–C bond accelerated electron transition and inhibited the rapid photogenerated electron pair recombination. In the degradation process of CIP, ˙O₂ ⁻ and h⁺ played a significant role. Experiments proved that C/BiOBr is practical and feasible for the degradation of CIP under the synergistic effect of adsorption and photocatalysis.

Fertilization influences the soil microbiome. However, little is known about the effects of long-term fertilization on soil microbial metabolic pathways. In this study, we investigated the soil microbiome composition and function and microbial participation in the N cycle according to the Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene ontology (GO) functional annotation of different genes in a metagenomic analysis after long-term fertilization. Fertilizer application significantly changed the soil C/N ratio. Chemical fertilizer (NPK) treatment decreased soil pH, and chemical fertilizer combined with straw (NPK+S0.5) treatment increased ammonium nitrogen (NH₄⁺-N) but decreased nitrate nitrogen (NO₃⁻-N). NPK, NPK+S0.5 and S0.5 applications did not change the soil microbiome composition or dominant phylum but changed the relative abundances of microbiome components. Moreover, fertilizer significantly influenced metabolic processes, cellular processes and single-organism processes. Compared with a no-fertilizer treatment (CK), the NPK treatment resulted in more differentially expressed gene (DEG) pathways than the NPK+S0.5 and S0.5 treatments, and these pathways significantly correlated with soil nitrate nitrogen (NO₃⁻-N), available phosphorus (AP) and the moisture content of soil (MC). KEGG analysis found that fertilizer application mainly affected the ribosome, photosynthesis and oxidative phosphorylation pathways. S0.5 and NPK+S0.5 increased microbial nitrogen fixation, and NPK and NPK+S0.5 decreased amoA and amoB and accelerated denitrification. Thus, organic fertilizer increased N fixation and nitrification, and inorganic N fertilizer accelerated denitrification. We found that the function of the soil microbiome under different fertilizer applications could be important for the rational application of fertilizer and for environmental and sustainable development.

Returning crop straw to the soil is an effective measure to increase soil fertility and maintain crop yield in agroecosystems. In this study, we conducted a 34-year field experiment (1984–2017) to investigate the relationships among the impacts of straw return on soil nutrients, phosphorus (P) fractions, phosphorus transformation-related functional microbial communities, and key genes in black soil. The results of the soil chemical properties showed that straw return could slow the decline in soil pH and increase soil nutrients, i.e., soil organic carbon (SOC), available K (AK), and available P (AP) concentrations, with the straw addition (PKS) treatment resulting in the highest soil AP and AK contents. Compared with conventional fertilizer (NPK) and conventional fertilizer with straw (NPKS), straw return alone (S) significantly increased the soil AP and AK contents by 1.1–42.8 and 38.3–114.3 mg/kg (p < 0.05), respectively. The results of the phosphorus fraction experiment indicated that long-term straw return promoted labile and moderately stable phosphorus content by altering the composition and increasing the relative abundances of functional genes regulating soil P activation (ugpQ, ppk, phoD, and gcd). The compositional changes in the phosphorus-cycling-related functional genes of the soil were affected mostly by soil total P (TP), AK, and NO₃⁻-N, whereas pH, SOC, and available N (AN) were the main environmental factors influencing the phosphorus-cycling-related microbial community composition. These direct measurements provide insight into the soil phosphorus fractions, phosphorus-cycling-related functional genes, and microbial communities associated with straw returning, which enhances our understanding of the chemical and biogeochemical behavior of soil phosphorus upon straw incorporation.

Declining soil fertility and reduced microbial diversity due to intensive farming threaten sustainable agriculture. This study aimed to assess the effects of B. japonicum inoculation and biochar amendment, applied individually and in combination, on soil properties, microbial communities, and soybean yield under field conditions in Jilin Province, China. A field experiment was established with four treatments: control (CK), B. japonicum alone (RH), biochar alone (CK2), and their combination (RHB). Observations were recorded at flowering (FS), seed-filling (SFS), and harvesting (HS) stages. Soil physicochemical properties, microbial diversity, and soybean yield were evaluated to determine treatment responses. The RHB treatment significantly improved soil fertility. Soil pH increased from 5.77 in CK to 6.20 in RHB, total nitrogen rose from 0.12% to 0.19%, and available phosphorus increased from 32.4 to 45.3 mg/kg. Available potassium and soil organic matter increased by 18.2% and 27.7%, respectively. Soybean yield was highest in RHB (3798 kg/ha) compared to CK (3158 kg/ha) and correlated strongly with total nitrogen (TN) ( r = 0.84), nitrate nitrogen ( r = 0.75), and available nitrogen ( r = 0.67). Microbial analysis revealed enrichment of beneficial genera, including Pseudomonas and Beauveria, along with higher populations of nitrogen-cycling bacteria and mycorrhizal fungi, thereby enhancing nutrient cycling. B. japonicum inoculation combined with biochar significantly enhanced soil fertility, improved microbial diversity, and increased soybean yield, offering a sustainable strategy to strengthen soil health and productivity in intensive farming systems.

In this paper, the high-performance photocatalytic copper oxide and bismuth oxychloride composite material is prepared with a simple hydrolysis method and is studied by various characterization methods. The results show that the moderately loaded copper oxide significantly enhances the degradation performance, visible light response ability, and interface charge transfer ability of bismuth oxychloride semiconductors, and the recombination of electron-hole pairs is obviously inhibited. Especially, when the content of added copper oxide is about 0.04 mmol, the composite material has a saturated adsorption rate of 53.07% for ciprofloxacin. Under the irradiation of visible light for 60 minutes, the removal rate of composite material for Ciprofloxacin reaches 93.15%, which is that of pure bismuth oxychloride 6.2 times. The photocatalytic effect is improved dramatically. After five times of recycling, the material presents favorable stability and outstanding photocatalytic activity. The possible photocatalytic mechanism is discussed that Superoxide radical is the leading radical group playing the significant role in the press of photocatalytic degradation of ciprofloxacin.