The establishment of high-yielding agricultural production systems is severely restricted by low soil organic carbon (SOC) and high Na⁺ concentration in saline-alkaline soils. In order to confirm the effects of biochar and phosphorus (P) fertilization on SOC sequestration, soil physical structure and inorganic P (Pi) fractions, as well as optimize the amount of P fertilizer, a field experiment was designed with two factors: with biochar at 0 (C0), 1% (C1) and 3% (C2); with P at 0 (P0), 64 (P1) and 128 kg ha⁻¹ (P2). The results indicated that biochar input enhanced SOC, however, the effect of P application on SOC and soil physical structure were negligible. Compared to C0, SOC was increased by 98–113% for C1 and 180–195% for C2. Due to the SOC enhancement and reduction of soil Na⁺ concentration, biochar input decreased ρb, increased MWD and WSMA. For Pi fractions, soil Olsen-P, Ca₂-P, Ca₈-P, Fe-P and Al-P were increased, mainly due to the direct supply, retention and the improvement of biological availability. Overall, C2P1 was the most efficiency treatment to enhance SOC, improve soil physical structure, and C2P2 avail to increase the supply capacity of soil P, but had no significant difference with that in C2P1.

Organic amendments have been widely confirmed to support soil health and agricultural sustainability. However, the effects and mechanisms of long-term organic amendments combined with chemical fertilizers on soil organic carbon (SOC) sequestration and soil macroaggregate formation are still unclear. Therefore, this study aimed to explore the interaction between soil carbon sequestration and soil agglomeration after 12 years of fertilization. Seven treatments within a field experiment were selected to conduct the research, including nitrogen (N) application by farmers, optimized N management, biochar and/or straw, manure, compost or biogas residue plus optimized N management. The results showed that the addition of organic materials significantly enhanced the SOC by 29.6–119.8% and 10.3–36.3% in 0–15 and 15–30 cm soil layers compared to N application by farmers, respectively. Meanwhile, the soil humus carbon pools in the 0–15 cm soil layer were increased by 14.7–205.2%, particularly humin carbon (HUC), which could be considered as a useful indicator of the soil carbon sequestration process. Among the organic materials, the addition of biochar was the most effective strategy due to its high aromatic carbon content that resisted biodegradation. The addition of organic materials also improved the soil labile carbon fractions, and the contents of microbial biomass carbon (MBC), dissolved organic carbon (DOC), particulate organic carbon (POC) and KMnO₄-oxidizable carbon (ROC) were enhanced by 120.5%, 92.3%, 217.2% and 85.5% on average, respectively, and the amount of exchangeable Ca²⁺ and Mg²⁺ cations and Fe and Al oxides in the soil increased significantly whilst the Na⁺ content declined in the 0–15 cm soil layer. These indicators showed a significant correlation with the mean weight diameter (MWD). Our results revealed that the addition of organic materials could be an effective management practice to promote soil carbon sequestration and soil macroaggregate formation in calcareous soil.

Plastic film mulching, widely used in agriculture, leads to microplastic (MP) pollution in soils. While biodegradable polybutylene adipate terephthalate (PBAT) films may offer a solution, their impacts on subsurface soils and microorganisms remain unclear. To investigate the effects of conventional non-biodegradable polyethylene (PE) and biodegradable PBAT MPs on the properties of sub-surface soils and microbial communities, MPs were added at varying doses in a field experiment and incubated for 160 days. Physicochemical characteristics, nutrient dynamics, and microbial composition, diversity, and networks of soils were analyzed using standard techniques and 16S rRNA/ITS gene sequencing. Correlations between soil properties and microbes were assessed. Both MP types significantly altered soil characteristics, with PBAT-MP elevating pH and the levels of available phosphorus and potassium more than PE-MP. Microbial composition shifts occurred, with low-addition PBAT-MP promoting plastic-degrading genera. The assessment of α/β-diversity indicated that PBAT-MP predominantly influenced fungi while PE-MP impacted bacteria. An examination of microbial co-occurrence networks highlighted that PE-MP primarily disrupted fungal interactions, whereas PBAT-MP streamlined network complexity. Correlation analyses revealed that PBAT-MP promoted fungal diversity/network resilience correlating to nutrients. PE-MP and PBAT-MP significantly altered native soil/microbe relationships. PBAT-MP may exert greater, yet unknown, impacts over time through its biodegradation into newer and smaller fragments. Future research needs to integrate multi-omics and stable isotope science to elucidate the deep mechanistic impacts of degraded film-derived MPs on microbial ecological functions and biogeochemical cycles. Attention should also be paid to the long-term accumulation/transport of MPs in agricultural soils. Overall, this work deepens the impact and understanding of MPs from plastic film on sub-surface soil ecology. Furthermore, it provides a theoretical foundation for managing ‘white pollution’ in the film-covered farmlands of arid and semi-arid regions in China.

Drought stress severely limits the productivity of sweet potato (Ipomoea batatas L.), yet the stage-specific molecular mechanisms of its adaptation remain poorly understood. Therefore, we integrated transcriptomics and extensive targeted metabolomics analysis to investigate the drought responses of the sweet potato cultivar ‘Luoyu 11’ during the branching and tuber formation stage (DS1) and the storage root expansion stage (DS2) under controlled drought conditions (45 ± 5% field capacity). Transcriptome analysis identified 8292 and 13,509 differentially expressed genes in DS1 and DS2, respectively, compared with the well-watered control (75 ± 5% field capacity). KEGG enrichment analysis revealed the activation of plant hormone signaling, carbon metabolism, and flavonoid biosynthesis pathways, and more pronounced transcriptional changes were observed during the DS2 stage. Metabolomic analysis identified 415 differentially accumulated metabolites across the two growth periods, with flavonoids being the most abundant (accounting for 30.3% in DS1 and 23.7% in DS2), followed by amino acids and organic acids, which highlighted their roles in osmotic regulation and oxidative stress alleviation. Integrated omics analysis revealed stage-specific regulation of flavonoid biosynthesis under drought stress. Genes such as CYP75B1 and IF7MAT were consistently downregulated, whereas flavonol synthase and glycosyltransferases exhibited differential expression patterns, which correlated with the selective accumulation of trifolin and luteoloside. Our findings provide novel insights into the molecular basis of drought tolerance in sweet potato and offer actionable targets for breeding and precision water management in drought-prone regions.

Enhancing photosynthesis is considered one of the most rational strategies to increase crop yield. However, the dominant physiological driving processes of photosynthesis at different maize growth stages under long-term fertilization remain unclear. Based on a 45-years field experiment, four treatments were selected—namely, CK (no fertilizers), N (276 kg N ha⁻¹), M (60,000 kg manure ha⁻¹), and MN (60,000 kg manure + 276 kg N ha⁻¹)—to study the response of maize physiological characteristics to fertilization. The results showed that long-term fertilization significantly changed the photosynthetic characteristics and endogenous hormones content. Among them, MN increased the photosynthetic rate (Pn) by 41.9–152.3% at different maize growth stages compared to CK. Organic fertilizer addition (M and MN) significantly increased superoxide dismutase (SOD), peroxidase (POD), and soluble sugar (SS) by 26.7–64.3%, 42.5–155.4%, and 16.4–89.5%, respectively. However, proline (Pro) and malondialdehyde (MDA) content decreased by 19.1–44.3% and 0.6-21.3%, respectively. Under these treatments, indole-3-acetic acid (IAA), gibberellins (GA), salicylic acid (SA), zeatin riboside (ZR), abscisic acid (ABA), SS, SOD, and POD were the main physiological driving indicators of photosynthesis. The result of PLS-SEM indicated that the main physiological driving pathways of photosynthesis were “IAA or ZR or SA-SOD-POD-Pn” and “GA or ABA-SOD or POD-SS-Pn”. Additionally, the maize grain yield of N, M, and MN increased by 111.2%, 218.1%, and 297.2% compared to CK, respectively. Overall, organic combined with nitrogen fertilizer could maintain a higher level of photosynthetic capacity by balancing endogenous hormones and enhancing the activity of antioxidant enzymes to support maize production.