Nitrous oxide (N₂O) is an overwhelming greenhouse gas and agricultural soils, particularly acidic soils, are the main source of its release to the atmosphere. To ameliorate acidic soil condition, liming materials are added as an amendment. However, the impact of liming materials has not been well addressed in terms of exploring the effect of soil pH change on N₂O emissions. In the present study, a soil with pH 5.35 was amended with liming materials (CaMg(CO₃)₂, CaCO₃, Ca(OH)₂ and CaO) to investigate their effects on N₂O emissions. The results indicate that application of liming materials reduced the magnitudes of N₂O emissions. The maximum reduction of soil N₂O emissions took place for Ca(OH)₂ treatment when compared to the other liming materials, and was related to increasing soil pH. Mineral N, dissolved organic C, and microbial biomass C were also influenced by liming materials, but the trend was inconsistent to the soil pH change. The results suggest that N₂O emission mitigation is more dependent on soil pH than C and N dynamics when comparing the different liming materials. Moreover, ameliorating soil acidity is a promising option to mitigate N₂O emissions from acidic soils.

Peanut cultivation is widely practiced using plastic mulch film, resulting in the accumulation of microplastics/nanoplastics (MPs/NPs) in agricultural soils, potentially negatively affecting peanut growth. To investigate the effects of two polystyrene (PS) sizes (5 μm, 50 nm) and three concentrations (0, 10, and 100 mg L⁻¹) on peanut growth, photosynthetic efficiency, and physiological characteristics, a 15-day hydroponic experiment was conducted using peanut seedlings as the experimental material. The results indicated that PS-MPs/NPs inhibited peanut growth, reduced soil and plant analyzer development (SPAD) values (6.7%), and increased levels of malondialdehyde (MDA, 22.0%), superoxide anion (O₂⁻, 3.8%) superoxide dismutase (SOD, 16.1%) and catalase (CAT, 12.1%) activity, and ascorbic acid (ASA, 12.6%) and glutathione (GSH, 9.1%) contents compared to the control. Moreover, high concentrations (100 mg L⁻¹) of PS-MPs/NPs reduced the peanut shoot fresh weight (16.1%) and SPAD value (7.2%) and increased levels of MDA (17.1%), O₂⁻ (5.6%), SOD (10.6%), POD (27.2%), CAT (7.3%), ASA (12.3%), and GSH (6.8%) compared to low concentrations (10 mg L⁻¹) of PS-MPs/NPs. Notably, under the same concentration, the impact of 50 nm PS-NPs was stronger than that of 5 μm PS-MPs. The peanut shoot fresh weight of PS-NPs was lower than that of PS-MPs by an average of 7.9%. Additionally, we found that with an increasing exposure time of PS-MPs/NPs, the inhibitory effect of low concentrations of PS-MPs/NPs on the fresh weight was decreased by 2.5%/9.9% (5 d) and then increased by 7.7%/2.7% (15 d). Conversely, high concentrations of PS-MPs/NPs consistently reduced the fresh weight. Correlation analysis revealed a clear positive correlation between peanut biomass and both the SPAD values as well as Fv/Fm, and a negative correlation with MDA, SOD, CAT, ASA, and GSH. Furthermore, the presence of PS-MPs/NPs in roots, stems, and leaves was confirmed using a confocal laser scanning microscope. The internalization of PS-MPs/NPs within peanut tissues negatively impacted peanut growth by increasing the MDA and O₂⁻ levels, reducing the SPAD values, and inhibiting the photosynthetic capacity. In conclusion, the study demonstrated that the effects of PS on peanuts were correlated with the PS size, concentration, and exposure time, highlighting the potential risk of 50 nm to 5 μm PS being absorbed by peanuts.

Over the past few decades, the discovery of novel microbial processes, biochemical reactions, and previously uncharacterized microorganisms has significantly enhanced our understanding of nitrogen (N) cycling across terrestrial and aquatic ecosystems, including engineered environments such as wastewater treatment systems. These scientific advancements are catalyzing a paradigm shift toward treatment strategies that are not only energy-efficient and cost-effective, but also environmentally sustainable, with the added benefit of mitigating greenhouse gas emissions. The current review highlights recent breakthroughs in microbial N cycling, with particular emphasis on their practical applications in wastewater treatment. Emerging processes, such as nitrous oxide (N₂O) mitigation, electro-anammox, ferric iron-dependent ammonium oxidation (Feammox), and complete ammonia oxidation (comammox), offer promising strategies for sustainable and low-energy N removal. Nevertheless, a significant challenge persists in translating these laboratory-scale innovations into full-scale, real-world applications, especially within decentralized treatment infrastructures. Bridging this gap is essential for realizing robust, low-carbon, and sustainable wastewater management systems in the decades to come.

The effects of biochar on soil N₂O emissions remain contentious, and the microbiological processes involved are not yet fully understood. Arbuscular mycorrhizal (AM) fungi, key players in soil nitrogen (N) cycling, may mediate the impact of biochar on plant N uptake and N₂O emissions, but this interaction remains unclear. This study involved a two-year field experiment to examine how varying biochar application rates affect soil microbial communities, particularly AM fungi at rainfed maize (Zea mays L.) farmland, and to assess how AM fungi influence soil N₂O emissions and maize growth under biochar addition with two AM fungi treatments (with and without suppression of native AM fungi). The results revealed that biochar significantly enhanced soil microbial diversity, especially the variety and richness of AM fungi. Biochar addition improved soil physicochemical parameters, including soil water content, bulk density, and inorganic N availability. Biochar also decreased AOA and AOB gene abundances, increased AM fungal gene abundances, lowered (nirK + nirS)/nosZ ratio, and reduced soil N₂O emissions. Suppression of native AM fungi increased N₂O emissions throughout the rainfed maize growing period, accompanied by a higher (nirK + nirS)/nosZ ratio. Biochar addition combined with non-suppressed AM fungi promoted maize growth, with the highest yield observed at 20 t ha⁻¹ biochar. Overall, biochar decreased N₂O emissions and strengthened the performance of AM fungi in rainfed maize farmland, highlighting the vital role of AM fungi s in soil N cycling under biochar addition. This study offers a scientific basis for using biochar in reducing N₂O emissions and increasing crop yield in dry farmland.

The accumulation of polylactic acid nano-plastics (PLA-NPs) in saline–alkali soils poses a potential threat to crop growth; however, the underlying toxicological mechanisms remain poorly understood. We conducted a hydroponic experiment to investigate the effects of polylactic acid (PLA) NPs (100 and 500 mg L⁻¹) under conditions both in the presence (50 mmol L⁻¹ NaCl) and absence of salt stress on maize seed germination, seedling growth, physiological characteristics, and transcriptomic responses. The results showed that exposure to PLA-NPs, particularly at a high concentration (500 mg L⁻¹), significantly inhibited seed germination and seedling growth. Compared to the low concentration (100 mg L⁻¹) of PLA-NPs, the high concentrations (500 mg L⁻¹) reduced the germination percentage by 25.0% and fresh weight by 25.8% and increased root MDA (6.7%), SOD (30.0%), POD (6.3%), ASA (13.4%), and GSH (13.1%). Under the same concentration of the PLA, PLA + NaCl treatments exerted stronger inhibitory effects than PLA-NPs alone, with the seed germination percentage and fresh weight reduced by an average of 52.7% and 6.6%, respectively. Notably, the inhibitory effects and integrated biomarker response (IBR) index of the PLA 500 + NaCl treatment were the highest. The presence of PLA-NPs in roots was confirmed using confocal laser scanning microscopy. GO enrichment analysis showed that pathways related to nutrient reservoir activity, oxidoreductase activity, hydrogen peroxide catabolic process, and hydrogen peroxide metabolic process were enriched under PLA-NP and PLA + NaCl treatments. KEGG analysis further indicated enrichment in phenylpropanoid biosynthesis, ABC transporters, and alpha-linolenic acid metabolism. The PLA-NP and PLA + NaCl treatments upregulated genes associated with oxidoreductase activity (Zm00001eb238800, Zm00001eb128620, and Zm00001eb020790). These findings suggest that synergistic toxicity of PLA-NPs and salinity stress in maize is primarily driven by the internalization of PLA-NPs and Na⁺ within maize roots, which negatively impacts maize seed germination and seedling growth by disrupting redox homeostasis and metabolic balance, thereby forcing plants to reallocate resources from growth toward oxidative stress defense. This study provides critical insights into the environmental risks of biodegradable nano-plastics in saline–alkali soil environments.