The application of organic fertilizer affects soil microbes and enzyme activities. In this study, we explored the effects of various long-term different fertilization treatments (manure, M; chemical fertilizer, NP; manure + chemical fertilizer, MNP; and no fertilizer, CK) on bacterial community structure and soil sucrase, urease, and alkaline phosphatase activities in Shaping, Hequ, China. High-throughput sequencing was used to amplify the third to the fourth hypervariable region of the 16S ribosomal RNA for analysis of the bacterial community structure. Enzyme activities were determined by colorimetry. Soil treated with MNP had the highest bacterial Abundance-based Coverage Estimator index and enzyme activities. The principal coordinates analysis results showed significant differences among the various fertilization treatments (p < 0.001). Proteobacteria, Actinobacteria, Acidobacteria, Gemmatimonadetes, and Chloroflexi were consistently dominant in all soil samples. The redundancy analysis and Monte Carlo permutation tests showed that the soil bacterial communities were significantly correlated with alkali-hydrolyzable nitrogen, organic matter, urease, and alkaline phosphatase. Our results reveal the fundamentally different effects that organic and inorganic fertilizers have on soil bacterial communities and their functions.

Straw return is an effective agricultural measure that influences the ecological environment. In the context of global climate change and the need for sustainable development, it is essential to explore how straw return methods affect the environment. This study conducted a two-year field experiment comparing different straw return treatments: no straw return (CK), straw return directly (SR), and straw returned in deep ditches (ISR). The results showed that SR treatment increased soil dissolved organic carbon (DOC) (21.7~25.8%) and dissolved organic nitrogen (DON) (8.5~43.8%) compared to CK. The ISR treatment significantly enhanced DOC (13.1~33.0%) and DON (14.2~50.8%). Both SR and ISR treatments also improved maize growth indicators, such as leaf area index (LAI), stem biomass, leaf biomass, and grain biomass. In terms of environmental effects, the ISR measure reduced N₂O emissions and significantly lowered the carbon footprint (CF) and water footprint (WF). Specifically, the yield-scale carbon footprint (CF_y) and yield-scale water footprint (WF_y) of ISR were reduced by 12.0% and 9.1%, respectively, in 2023. Correlation analysis revealed that soil DON and DOC were key factors in these environmental benefits. Furthermore, the reduction in WF and CF was closely linked to the increased SWC and higher biomass in all maize organs. Therefore, we demonstrated that the ISR measure not only promotes maize biomass accumulation but also effectively mitigates carbon emissions and water consumption on farmland. It may be related to the boosting soil DON and DOC levels. Overall, the ISR method holds promise for supporting sustainable farming practices.

Soil eukaryotic microorganisms are important to biodiversity, and returning different kinds of organic materials to the field could improve the biodiversity of soil eukaryotic microorganisms. However, no detailed research has been conducted in the northern China semi-arid area in returning the different organic materials to the field and determining the status of eukaryotic microorganisms. Therefore, we explored the effects of various organic materials returning to the soil in combination with inorganic fertilizer on the diversity and community structure of eukaryotic microorganisms in Shanxi province, China. Soil samples were collected from five different fertilization treatments: chemical fertilizer (F), chemical fertilizer + cattle manure (FM), chemical fertilizer + straw (FS), chemical fertilizer + pig manure (FC) and control without fertilizers (CK). High-throughput sequencing was applied to analyze the eukaryotic diversity and community structure. Results showed that the dominant eukaryotic microorganisms among soil samples were Fungi, Viridiplantae, Metazoa and Protist. Although α-diversity was not significantly different among the five treatments, principal coordinate analysis and permutational multivariate analysis of variance illustrated significant differences (p < 0.001) in β-diversity of eukaryotic microorganism under treatments with different organic materials. Redundancy analysis showed that the soil properties, including total potassium, available nitrogen, available potassium and organic matter were the main factors attributed to eukaryotic microorganisms’ community structure in this region.

How different fertilization practices modify soil organic carbon (SOC) sequestration is still unclear. Our study aimed to evaluate the changes in SOC stocks and their physical fractions after 10 years of organic and inorganic fertilization. Five treatments were established under a wheat-maize system in Northern China: control (CK), chemical fertilizer (F), straw plus chemical fertilizer (SF), manure plus chemical fertilizer (MF), and straw and manure plus chemical fertilizer (SMF). The results showed that the SOC sequestration rate at 0–20 cm depth decreased in the following order: SMF (1.36 Mg C/ha/yr) > MF (1.13 Mg C/ha/yr) > SF (0.72 C/ha/yr) > F (0.15 Mg C/ha/yr) > CK (−0.25 Mg C/ha/yr). The values indicated that straw returning and manure application were important measures to achieve the “4 per 1000” target, and the application of manure was a more effective strategy. The high input of chemical fertilizer only maintained the initial SOC level and was not a powerful C-farming practice. A minimum input of 4.93 Mg C/ha/yr was required to keep the initial SOC storage. The SOC associated with small macroaggregate (0.25–2 mm) was the most sensitive indicator for the changes of bulk SOC. In addition, the accumulation of SOC under SMF, MF, and SF treatments mainly occurred in the occluded particulate organic C (oPOC) in small macroaggregates, indicating that the physical protection of macroaggregates played a predominant role in SOC sequestration. The SMF, MF, and SF treatments also displayed higher mineral organic C (mSOC) in soil aggregates than the CK and F treatments. A transformation of oPOC towards the mSOC fraction indicated that exogenous C further shifted into stable C pools under the physical protection of soil aggregates. In conclusion, these findings confirmed the important role of straw returning and manure application in SOC accumulation and stabilization, highlighting that a combination strategy of straw + manure + chemical fertilizer had the best effect.

The scarcity and uneven distribution of precipitation present significant challenges for agriculture in arid regions. Fertilization can improve crop yields and water productivity (WP) under these conditions. However, the effects of different long-term fertilization practices on maize yield and WP under varying precipitation patterns require further research. A 30-year fertilization experiment was conducted to investigate the effects of different fertilization treatments on maize yield, WP, soil organic carbon (SOC), and the correlations among these factors. The treatments included no fertilization, application of chemical fertilizers alone, combined application of chemical fertilizers and cattle manure, and application of a high amount of cattle manure alone. Chemical fertilizers, cattle manure, and the combined application of chemical fertilizers and cattle manure significantly increased maize yield by 61.81–86.14%, 121.0%, and 114.5–125.5%, and increased WP by 59.4–84.9%, 119.4%, and 111.9–126.5%, respectively, compared to the unfertilized control. The combined application of chemical fertilizers and cattle manure resulted in optimal maize yield and WP, while also substantially reducing the coefficient of variation in maize yield (by 19.9–25.9% compared to the control) under interannual precipitation fluctuations. Compared with the no fertilization treatment, the average increase in maize yield peaks in very wet years, while WP reaches its highest level in relatively dry years. Maize yield was significantly positively related to SOC, WP, and water consumption during growth (p < 0.01). SOC was also significantly positively correlated with WP (p < 0.01). For every unit increase in SOC, the WP increased by 0.3955 kg ha⁻¹ mm⁻¹. In summary, the integrated application of organic and inorganic fertilizers is a proven strategy to enhance crop productivity and resilience, while concurrently improving WP and SOC. This synergistic approach represents a cornerstone for climate-resilient and sustainable dryland agriculture.

The overuse of antibiotics has led to the dissemination of antibiotic resistance genes (ARGs) in agricultural ecosystems, posing a threat to food safety. While current research on ARG transfer in soil–crop systems mainly concerns raw-consumed vegetables like lettuce, its impact on staple crops remains insufficiently studied. This study investigates how organic fertilizer affects ARG dissemination in the soil–millet system. Four fertilization treatments were established: no fertilization (CK), chemical fertilizer only (F), chemical fertilizer combined with manure (FM1), and chemical fertilizer combined with double amount of manure (FM2). Samples were collected from millet rhizosphere soil, roots, stems, leaves, and grains. High-throughput quantitative PCR was employed to investigate the transfer and dissemination of ARGs across the soil–millet system. Results showed that a total of 130 ARGs and 13 mobile genetic elements (MGEs), belonging to 17 gene families, were detected across all samples. The number of unique ARGs was higher in treatments FM1 and FM2 with manure. The accumulated absolute abundances of ARGs, MGEs and gene families all showed an order of FM1 > CK > FM2 > F. Pearson correlation analysis showed a close correlation among ARGs and MGEs. Although organic fertilizer application increased the absolute abundance of ARG-related genes in the rhizosphere soil and millet tissues, posing a potential threat to food safety, the rational strategy employed in the FM1 treatment effectively reduced ARG accumulation in millet leaves and grains. Therefore, this optimized application rate is recommended for millet production.