Plastic film mulch (PM) increases crop yield and nutrient use efficiency in arid regions by improving soil water and rhizosphere conditions. However, its impacts on microbially mediated phosphorus (P) bioavailability and soil P pools in dryland spring maize remain unclear. A field experiment (2019–2022) on the Loess Plateau with two P input (with/without) and two mulching (with/without) regimes was conducted to investigate the effects of PM on maize yield and rhizosphere bacterial and fungal communities. Results showed that PM increased maize yield by 14% and 11% and aboveground P uptake by 18% and 13% under P-unfertilized and P-fertilized conditions, respectively. PM increased bacterial alpha diversity, shifted community composition toward Proteobacteria, and reduced the relative abundance of Actinobacteriota, while bacterial assembly remained predominantly stochastic. In contrast, PM decreased fungal alpha diversity, with Ascomycota remaining the dominant phylum at both the V3 and V10 stages. Under P-unfertilized condition, PM weakened bacterial network connectivity and robustness but increased network size and centralization. Conversely, under P-fertilized conditions, PM induced contrasting patterns in fungal networks. PM also restructured microbial assemblages associated with soil available P, favoring functionally beneficial taxa (e.g., Proteobacteria) and genes (e.g., pqqC, gcd, based on functional prediction). Lastly, path analysis indicated that PM indirectly promoted the mobilization and depletion of soil available P through the suppression of enzyme activities and reorganization of microbial functional groups. These findings underscore the potential of optimized plastic mulch management in dryland agriculture, while emphasizing the importance of dynamic soil P monitoring to maintain long-term P sustainability.
Soil salinization poses a major constraint on rice productivity. This study evaluated the integrative effects of three amendments (zeolite, coconut coir, and humic acid) combined with slow-release urea on rice growth, rhizosphere bacterial communities, and soil nitrogen dynamics under salt stress. Results demonstrated that zeolite, particularly when combined with slow-release urea, exhibited the most pronounced benefits. It significantly enhanced soil bacterial diversity and reshaped the community structure by enriching dominant taxa, with Acidobacteria and Gemmatimonadetes abundances increasing by 110–242% and 138–236%, respectively, compared with other treatments. These microbial shifts were strongly correlated with increased soil available nitrogen and total potassium. Functionally, zeolite improved rice photosynthetic rate by 13–67% and panicle K+ content by 6–16%, while reducing whole-plant Na+ accumulation by 2–20%. Consequently, this treatment consistently produced the highest grain yield. Our findings indicate that zeolite combined with slow-release urea optimizes the rhizosphere microenvironment and nutrient availability, thereby enhancing rice physiological performance and productivity under salt stress. This integrated strategy offers a promising approach for sustainable crop production.
Ammonia-oxidizing microorganisms are important contributors to agricultural nitrous oxide (N2O) production, yet how cumulative management intensity is associated with the abundance, community structure, and potential activity of ammonia-oxidizing archaea (AOA), bacteria (AOB), and complete ammonia oxidizers (comammox) remains insufficiently understood. Here, we developed a continuous agricultural management intensity (AMI) index from six management variables and applied it to wasteland, orchard, farmland, and vegetable-field systems at three sites representing Mollisol, Entisol, and Ultisol soils. By combining inhibitor-based potential activity assays, quantitative PCR, and high-throughput sequencing, we evaluated the abundance, community structure, and potential activity of ammonia oxidizers and their contributions to potential N2O production. Within each site, AOB abundance and potential ammonia oxidation rates generally increased from low-AMI wasteland systems toward higher-AMI vegetable systems, whereas AOA and comammox contributed more to potential ammonia oxidation under some low-AMI conditions. These patterns were associated with higher inorganic N availability, lower soil pH, and differences in soil organic carbon. High-AMI systems also had a greater relative abundance of Nitrosospira clade 3a.2. Inhibitor-based estimates showed that AOB accounted for the largest proportion of potential N2O production, while AOA and comammox contributed less even when they contributed substantially to potential ammonia oxidation. Together, the AMI index complements categorical land-use descriptions by quantifying cumulative management pressure and provides a quantitative framework for identifying management states associated with AOB functional dominance and elevated potential N2O production within the three study sites examined.
Agriculture is a major source of greenhouse gas (GHG) emissions in the Yangtze River Economic Belt (YEB). Understanding the evolutionary trajectory of agricultural emissions and identifying targeted mitigation strategies are critical to advancing regional low-carbon transition and fulfilling China's carbon peak and carbon neutrality pledges. This study quantifies agricultural greenhouse gas emissions (AGHGE) for 11 YEB provinces from 2000 to 2024 using the IPCC Tier-2 methodology, decomposes the driving factors with the Logarithmic Mean Divisia Index (LMDI), and projects future emission trajectories under three scenarios using the STIRPAT model with Monte Carlo sensitivity analysis. Results show that AGHGE reached its peak of 768.99 Mt. CO2e in 2013 and declined to 604.96 Mt. CO2e by 2024, representing a reduction of 21.33% from the peak. Agricultural material inputs emerged as the fastest-growing source category, whereas crop cultivation and animal husbandry emissions declined. Methane remained the dominant gas, contributing 52.2% of total emissions in 2024. LMDI decomposition identifies land economic output intensity as the principal driver of emission increases and production efficiency as the main mitigating factor. Under Business-as-Usual, Conventional Policy, and High-quality low-carbon Development scenarios, 2030 emissions are projected at 693.97, 683.04, and 670.17 Mt. CO2e, respectively—14.71%, 12.91%, and 10.78% above the 2024 baseline. Sensitivity analysis identifies the single-cropping rice emission factor (Area B) as the dominant accounting-stage uncertainty (65.58% variance contribution) and sown-area elasticity as the primary forecasting-stage uncertainty. The findings support differentiated, province-specific mitigation strategies that integrate input-efficiency improvements, water-management interventions, and manure-management upgrades within a soil-health framework.
Conservation tillage (CT) promotes soil organic carbon (SOC) sequestration by increasing residue input and enhancing physical protection. However, the biological mechanisms driving SOC fraction formation across different soil depths under CT remain poorly understood. We investigated these mechanisms using data from an 8-year field experiment in Northeast China with three treatments: rotary tillage without straw mulching (RT), no-till without straw mulching (NT), and no-till with straw mulching (NTS). We quantified SOC fractions including particulate organic carbon (POC) and mineral-associated organic carbon (MAOC), plant-derived C (PC, via lignin phenols), microbial-derived C (MC, via amino sugars), and extracellular enzyme activities. Results showed that the 0–20 cm layer was co-dominated by POC and MAOC, whereas the 20–30 cm layer was dominated by MAOC (accounting for 79–96% of SOC). Formation pathways also differed between depths: in the 0–20 cm layer, POC accumulation was primarily associated with PC accumulation, while MAOC formation involved contributions from both PC and MC. In contrast, in the 20–30 cm layer, both POC and MAOC were more closely associated with microbial-derived C. Compared with RT, NT increased PC and MC concentrations by 34% and 6%, respectively. Compared with NT, NTS further enhanced PC and MC concentrations by 35% and 73%, respectively. These percentages represent treatment comparisons averaged across the 0–30 cm soil profile, rather than layer-specific responses. Additionally, NT enhanced the activities of C- and N-acquiring enzymes, thereby accelerating residue turnover and transformation. Overall, these findings indicate that conservation tillage regulates SOC accumulation through depth-dependent and fraction-specific pathways, with plant-derived C contributing mainly to topsoil POC formation and microbial-derived C becoming more closely associated with MAOC stabilization at depth.
