From a global perspective, the basic mapping and investigation of the loess sinkholes are far less extensive and in-depth than those of karst sinkholes. To some extent, this has limited people's understanding of the morphological characteristics, development patterns, and formation mechanisms of the loess sinkholes. The Chinese Loess Plateau (CLP) features the most typical loess landforms in the world, where tens of thousands of loess sinkholes have developed. However, due to the lack of high-precision and high-resolution survey data, the identification, characterization, and quantification of sinkholes in the CLP are basically blank, which significantly hinders in-depth research on loess sinkholes. In this study, we investigated a typical watershed in the CLP using photogrammetry, airborne laser scanning, and a handheld laser scanner. Based on previous studies, this paper introduces indices and methods for the morphological quantification of loess sinkholes and constructs the first-ever dataset of loess sinkhole morphology containing 1194 records at the basin scale. On this basis, we completed the spatial mapping of loess sinkholes, analysis of distribution patterns, morphological analysis, size-frequency analysis, fitting analysis of different parameters, estimation of subsurface soil erosion, in-depth investigation of typical sinkholes, and quantification of the contributions of different factors to sinkhole development. These efforts provide rich information for a deeper understanding of the morphological characteristics and genesis of loess sinkholes and offer data support for comparative studies with sinkholes in other regions. More importantly, we preliminarily estimate that the subsurface soil erosion triggered by sinkholes in the study area reaches as high as 345 000 metric tons. This finding underscores that loess sinkholes are not only a geological disaster but also a serious form of soil loss, highlighting their undeniable significance in regional soil erosion studies and laying a solid foundation for subsequent research and disaster prevention efforts. Furthermore, we suggest that the integration of airborne laser scanning and handheld laser scanning may represent a new trend in the detailed investigation of sinkholes in the future. This dataset is available on the Zenodo platform (10.5281/zenodo.14000267, Hu et al., 2025).

Single-tree diameter at breast height (DBH) and tree height (H) are fundamental parameters for forest inventory, forest structure characterization, and forest carbon stock estimation. However, single-source LiDAR data cannot simultaneously capture complete trunk and canopy structural information, limiting the accuracy of single-tree structural parameter estimation. To address this issue, a Bi-Directional Cross-Attention Fusion Network (BCAF-Net) is proposed to estimate DBH and H separately by integrating ground-based Simultaneous Localization and Mapping LiDAR (SLAM LiDAR) and Unmanned Aerial Vehicle LiDAR (UAV LiDAR) data. The framework employs a dual-branch encoder and a bidirectional cross-attention mechanism to establish cross-view structural relationships between trunk and canopy observations, enabling effective multi-source feature fusion. Experiments conducted at two urban forest sites demonstrated that BCAF-Net achieved the highest estimation accuracy, with RMSE of 0.82 cm for DBH and 0.91 m for H and corresponding R2 values of 0.97 and 0.96, respectively. Furthermore, the model maintained stable performance under varying forest structural complexities, cross-site conditions, and tree species. These results demonstrate that cross-view structural interaction effectively exploits complementary information from SLAM LiDAR and UAV LiDAR data, thereby improving single-tree structural parameter estimation in complex forest environments.

Abstract. From the perspective of the world, the basic mapping and investigation of the loess sinkhole is far less extensive and in-depth than that of the karst sinkhole survey. To some extent, this hinders people’s understanding of the morphological characteristics, development rules, and formation mechanisms of the loess sinkholes. Chinese Loess Plateau (CLP) has the most typical loess landform in the world, and tens of thousands of loess sinkholes have developed. However, due to the lack of high-precision and high-resolution survey data, the identification, characterization, and quantification of sinkholes in the Loess Plateau are basically blank, which seriously hinders the in-depth study of loess sinkholes. We investigated a typical watershed on the Chinese Loess Plateau using photogrammetry, airborne laser scanning, and handheld laser scanner. Based on previous studies, this paper proposes indices and methods for the morphological quantification of loess sinkholes and constructs the first dataset of loess sinkhole morphology containing 1194 records at the basin scale. On this basis, we completed the spatial mapping of loess sinkholes, analysis of distribution patterns, morphological analysis, size-frequency analysis, fitting analysis of different parameters, estimation of subsurface soil erosion, in-depth investigation of typical sinkholes, and quantification of the contributions of different factors to sinkhole development. These efforts provide rich information for a deeper understanding of the morphological characteristics and causes of loess sinkholes and offer data support for comparative studies with sinkholes in other regions. More critically, we preliminarily assessed that the subsurface soil erosion triggered by sinkholes in the study area amounts to as high as 345,000 metric tons. This finding makes it increasingly clear that loess sinkholes are not only a geological disaster process but also a serious soil loss process, highlighting their undeniable significance in regional soil erosion studies and laying a solid foundation for subsequent research and disaster prevention efforts. Moreover, we believe that the integration of airborne laser scanning and handheld laser scanning may represent a new trend in the detailed investigation of sinkholes in the future. The dataset is available from Zenodo platform (https://doi.org/10.5281/zenodo.14000267).

Sustainable phosphorus (P) management requires balancing resource efficiency, recycling safety, and eutrophication mitigation. Here, we integrated dynamic substance flow analysis with Bayesian structural time series modelling to reconstruct anthropogenic total phosphorus (TP) metabolism and assess policy-associated pathway changes in the Erhai Lake Basin, China, from 1992 to 2022. Anthropogenic TP losses showed a rise-peak-decline trajectory, peaking at around 850 t P yr−1 (2009–2011) before declining to 90–120 t P yr−1 post-2018. The basin P system shifted from high fertilizer and feed inputs, livestock manure pressure, and high-volume direct recycling toward lower external inputs, stronger waste-management interception, tailwater reuse/export, and more controlled recycling pathways. Counterfactual results showed delayed reductions after 2003, more sustained reductions after 2009, and the strongest recent response after 2017. The proposed framework provides a transferable approach for evaluating nutrient-resource governance and policy-associated P loss reduction in managed watersheds.

Due to global warming, the Qinba Mountain Area in China has experienced frequent extreme heavy rainfall events, transforming isolated geological hazards into multi-hazard chains characterized by cascading and compound disasters. These occurrences often lead to severe casualties and socioeconomic losses. To investigate the formation mechanisms of typical landslide-debris flow disaster chains in this region, this study selected the Gaojiawan disaster chain—a representative case within the study area—for systematic analysis. Using integrated methodologies, including unmanned aerial vehicle (UAV) mapping, geographic information system (GIS) spatial analysis, and a numerical simulation method based on PFC3D, the entire disaster chain process was reconstructed and investigated. The results show that collision interactions between cascading hazards were found to amplify the affected area and debris flow interactions fundamentally altered deposition mechanisms, transforming localized slope accumulation into integrated mass transport processes. This paper analyzes the transformation of the landslide debris flow disaster chain from the perspective of energy. Additionally, based on the analysis of field investigation and numerical simulation results, the formation mechanism of the Gaojiawan landslide-debris flow disaster chain is summarized into five stages: landslide formation stage, landslide activation stage, slope deposit mixing stage, debris flow formation stage, and low-speed deposition stage. This research elucidates the evolutionary dynamics and underlying mechanisms of landslide-dominated geohazard chains in mountainous regions. The proposed integrated monitoring-modeling framework provides methodological references for theoretical research and risk mitigation of similar disaster chains worldwide.

Sinkholes induced by soil piping are widely distributed globally, posing significant threats to ecological environments, agricultural production, and infrastructure. Compared with karst sinkholes, soil-piping-induced sinkholes are generally smaller and less detectable, posing persistent challenges to their accurate detection and mapping using deep learning approaches. To address this issue, this study proposes a novel Multimodal Attention Fusion U-Net (MAF-UNet) that adaptively integrates spectral texture information and topographic morphological features through a cross-modal attention fusion module (CFA), enabling automatic identification, segmentation, parameter extraction, and cataloging of loess sinkholes. The proposed network adopts a dualbranch encoder architecture incorporating residual double convolution (RDC), the Convolutional Block Attention Module (CBAM), and gated skip connections to enhance feature representation. A composite loss function combining Binary Cross-Entropy (BCE), Focal, and Tversky losses is employed to mitigate sample imbalance. Experiments conducted in the Heyang loess tableland, China, demonstrate that the combination of Digital Orthophoto Map (DOM), closed depressions, and slope as input factors achieves the best performance, with a Precision of 0.92, an F1-score of 0.91, an Intersection over Union (IoU) of 0.83, a mean Intersection over Union (mIoU) of 0.91, and a Precision-Recall Area Under Curve (PRAUC) of 0.94, significantly outperforming singleand dual-factor combinations. Ablation experiments further confirm that the CFA module is the most critical contributor to model performance. Transferability experiments conducted in Laozi Gully (Huining County) and Banyan Gully (Huzhu County) demonstrate that MAF-UNet exhibits strong robustness under the complex terrain conditions of the Loess Plateau. Overall, the proposed MAF-UNet supports an end-to-end workflow for automatic sinkhole mapping encompassing data preprocessing, model training and validation, prediction, segmentation, parameter extraction, cataloging, and mapping. It provides an effective methodological framework for automatic sinkhole hazard detection and mapping in the Loess Plateau and analogous regions.

Edge zones along deep-cut channels in rainfed plateaus are crucial farmlands but suffer persistent soil moisture (SM) reduction that constrain crop productivity. To quantify these dynamics, hourly SM at 10, 40, and 70 cm depths was monitored at three sites (at 3.5, 7, and 11.5 m from the channel edge) during the 2023-2024 apple growing season in the Weibei rainfed Plateau. Results show 8-27 % lower SM in edge zones than inner zones, especially at 40 and 70 cm soil depths, with the strongest impacts during fruit growth stage. Deficits intensified near channel margins due to root uptake by sidewall trees, which consumed 25-43 % of rainfall in growing season. Only heavy rainstorms penetrated deep enough to fully replenish root-zone water, while smaller events provided short-lived relief. The difference in soil water storage (DSWS) between inner and edge zones increased with cumulative reference evapotranspiration and initial DSWS, but declined with greater rainfall depth. In dry years, edge-zone apple trees faced intensified competition from sidewall vegetation, capturing proportionally less rainfall than inner-zone trees. These findings highlight vegetation-rainfall interactions as dominant controls of edge-zone water stress and underscore the need for management strategies that integrate vegetation regulation with rainstorm-mimicking irrigation to sustain orchard productivity in rainfed plateaus.

Headcut erosion is a fundamental geomorphic process governing the headward development of rills, gullies, and channels, contributing substantially to land degradation and downstream material production. Existing models generally assume that the entire inflow forms a free falling jet, neglecting on-wall flow and limiting their applicability under mixed-flow conditions. To address this limitation, we extend the model of Alonso et al. (2002) by partitioning inflow into jet and on-wall flow components and incorporating inflow discharge and headwall height into the formulation. The model was calibrated and validated using laboratory experiments conducted under both jet flow only and mixed flow conditions. The proposed framework reproduced the observed plunge pool depth (SD), plunge pool migration rate (Mp), and headwall migration rate (Mh) with NSE of 0.99, 0.82, and 0.97, respectively. Under mixed flow conditions, explicitly accounting for on-wall flow reduced the RMSE of plunge pool depth from 0.12 to 0.012 m and that of plunge pool migration rate from 3.13 × 10⁻⁵ to 1.13 × 10⁻⁵ m/s relative to the jet flow only formulation. Sensitivity analysis indicated that plunge pool depth was primarily controlled by critical shear stress (τc), plunge pool migration by the height correction coefficient (k), and headwall migration by the on-wall flow velocity ratio (λ). Furthermore, increasing inflow discharge accelerated both plunge pool development and headcut retreat, whereas increasing headwall height promoted plunge pool deepening and migration but reduced headwall retreat. These findings demonstrate the importance of coupled jet and on-wall flows for predicting headcut evolution under varying hydraulic conditions.

Aquatic phosphorus (P) transformations are fundamental to water quality. While microscale experiments and macroscale models have advanced understanding of P cycling, their largely independent development has yielded a fragmented view of aquatic P dynamics, limiting the accuracy of P management across scales. Given the growing urgency of global water-quality governance, closer integration across scales is needed to provide a more predictive foundation for managing and mitigating P dynamics.

Loess sinkholes are extensively developed across the Loess Plateau in north-central China and have frequently evolved into chain geological hazards under intense rainfall in recent years, severely impacting regional human safety and economic development. Consequently, this study selected a typical loess sinkhole-landslide-mudflow chain (LSLMC) as the research focus. Field investigations, unmanned aerial vehicle mapping, laboratory experiments, and theoretical analyses were conducted. The scales, morphologies, types, combinational patterns, and spatial correlations of sinkholes were examined. Morphogenetic characteristics of sinkholes, landslides, and mudflows were analyzed. The hazard-inducing effects of sinkholes were revealed, and an evolutionary model for the typical LSLMC was proposed. The results indicate that: (i) The sinkholes exhibit significant spatial autocorrelation in both formation size and developmental location. Their frequency decreases as size increases. Distinct clusters of low values are observed in morphometric characteristics, whereas pronounced clusters of high values occur in elevation. (ii) The development zones of sinkholes strongly correlate with areas exhibiting a high Topographic Wetness Index (TWI) and a low Stream Power Index (SPI). The sinkholes primarily serve as preferential flow conduits and sediment transport pathways, and the interconnection of sinkholes can trigger landslides. (iii) During the formation of LSLMC, mudflow materials originate not only from loose deposits created by sinkholes and landslides but are also amplified by erosion-induced enlargement effects. The formation process of the LSLMC is summarized into six stages. This study presents the first integrated UAV, laboratory tests, and spatial correlation analysis to provide process-based insights into the formation and evolution mechanisms of the LSLMC. These findings improve the understanding of sinkhole hazard mechanisms and offer theoretical support for preventing and mitigating loess-related hazard chains in small watersheds.

Geological disasters, as major natural hazards threatening regional sustainable development, have made risk assessment and planning governance core issues in global spatial safety management. This study, set against the backdrop of Shiquan County, a typical mountainous river-valley-type city in China, conducts landslide susceptibility prediction. We evaluated the performance of six machine learning models (LR, SVC, BP neural network, RFC, CatBoost, LGBM) in landslide susceptibility mapping. We proposed an optimization method based on "Neighborhood Feature Aggregation (NFA)". Among them, the CatBoost model performed the best. The study found that the proportion of geological disaster susceptibility zoning in Shiquan County exhibits a gradient distribution and shows a linear distribution along river valleys spatially. Based on the research findings, urban disaster prevention strategies are proposed from the perspective of social risk, providing references for other mountainous valley-type cities with characteristics similar to those of Shiquan County.

Due to difficulties in direct field observation and uncertainties in glacier runoff models, accurately estimating the glacier runoff remains one of the foremost challenges in cryospheric science. Using a digital elevation model (DEM) and orthophotos (both with a resolution of 5 cm) obtained from an unmanned aerial vehicle (UAV), this study developed a novel remote sensing method for estimating the annual discharge of the supraglacial channel over Qiyi Glacier in the northern Tibetan Plateau, which contributes to the majority of the glacier runoff. Our results showed that the catchment areas of the six main supraglacial channels covered 92.02 % of the total glacier area and transported 89.43 % of the annual surface meltwater yield (each ranging from 0.07x106 to 0.66x106 m3). Some geometric parameters of the supraglacial channels (including lateral deviation, gradient, and width) were selected to predict the annual discharge using a stepwise regression model, which explained similar to 78.2 % of the variance in the measurement-based glacier annual discharge, with the explained variance increasing to 81.8 % after five-point moving average filtering. In comparison, a nonlinear regression model incorporating only the lateral deviation and specific gradient, which were more easily obtained practically, performed somewhat less well, accounting for 66.2 % of the discharge variation; however, the explained variance increased to 81.4 % after five-point filtering. If satellite remote sensing data with meter-level spatial resolution are available for a specific glacier research area, our regression models, based solely on the UAV-derived supraglacial channel network, will be a promising solution for monitoring changes in annual glacier discharge.

Accumulation landslide induced by rainfall is one of the most important types of geological disasters in the Qinling-Bashan Mountains, China. In recent years, nearly one hundred accumulation landslides have caused significant casualties and serious economic losses. To better understand the response mechanism of sliding zone soil to such landslides under rainfall infiltration conditions, the landslide in Zhashui County, Shaanxi Province, was taken as a typical case. The field investigation, ring shear test and creep test were carried out using sliding zone soil. Combined with the laboratory tests results, the landslide was numerically simulated and analysed. Laboratory test results show that the increase in moisture content leads to a reduction in the shear strength of the sliding zone soil, promoting slope creep and accelerating the deformation of the slope. Numerical simulation results for two typical rainfall infiltration scenarios, short-duration heavy rainfall and long-duration weak rainfall, indicate that the failure type of accumulation landslide is a creep-slide failure, and the damage degree of the heavy rainfall to the slope is greater than that of the weak rainfall. According to the results of the field investigation and numerical simulation, we find that the mechanical behaviour of the sliding zone soil controls the failure mode of the accumulation landslide in Qinling-Bashan Mountains. This kind of landslide has roughly experienced three failure stages: the early disaster-breeding stage, the interim accelerated deformation stage and the anaphase instability failure stage.

The abrupt changes of soil properties after shallow landslides were found to greatly increase the soil erosion on loess slopes in field and laboratory experiments in Loess Plateau, but which properties play the dominant role under various conditions is still unclear. To address this issue, a simplified runoff and soil erosion model was applied to quantitatively identify the contribution of four changed properties at the landslide scar on soil erosion aggravation after a shallow landslide. The slope angle, soil, and the length and location of the landslide scar were further analysed in detail to determine if the dominant roles vary with these parameters. The results show the model can accurately simulate the sediment yields before and after shallow landslides. After shallow landslides, the increasing rainfall excess rate and soil erodibility play dominant roles in soil erosion aggravation, which cause 4.95-90.75 and 3.08-17.92 times larger sediment yields, respectively, than those before shallow landslides. Moreover, the effects of increasing rainfall excess rate and soil erodibility can complement and reinforce each other in the soil erosion aggravation following a shallow landslide. A sensitivity analysis shows that the dominant factors remain unchanged, even though the impacts of changed soil properties on soil erosion aggravation can vary substantially for different slope angles and shallow landslide characteristics. In addition, using a temporally varying soil erodibility in the landslide path can account for the impact of remnant loose soil over there, and the simulation agrees much better with the observations. These results are expected to deepen our understanding of how shallow landslides aggravate the following soil erosion and formulate an optimal strategy to control the combined gravity-hydraulic erosion in the Loess Plateau.

Loess landslides caused by the freeze-thaw cycle (FTC) have become increasingly frequent. In this study, a typical loess landslide in the seasonal freeze-thaw area was taken as the research object. Triaxial creep tests and scanning electron microscope tests were conducted on the undisturbed loess after FTC. The effects of FTC on the creep characteristics, long-term strength, and microstructure of loess were revealed, and the mechanism of FTC-induced loess landslides was discussed as well. The results show that (1) after FTC, the creep deformation of the sample noticeably increases, and the influence of FTC on the shallow loess is greater. (2) The long-term strength of loess after FTC obviously decreases. As the FTC times rise, the long-term strength initially declines, then increases, and then decreases again. The deterioration effect of FTC on shallow loess is more pronounced. With the increase in moisture content, the long-term strength of loess decreases, and the FTC action gradually weakens the strength difference caused by the change in moisture content. (3) The microstructural analysis of loess samples revealed that FTC results in the change of loess microstructure, the weakening of particle cementation, and the instability of particle contact. (4) FTC leads to the accumulation and evacuation cycle of groundwater in the slope. The formation process of freeze-thaw loess landslides is divided into initial stability stage, freeze-thaw deterioration stage, fracture development, and sliding surface formation stage and slope instability stage. The research results provide a new understanding for the study of loess creep characteristics and the formation mechanism of loess landslides.

Oil and gas pipelines, as linear infrastructure spanning multiple regions, are highly susceptible to geological hazards. Previous research has focused on discrete hazard points, yet failure at a single point can compromise the integrity of the entire system, underscoring a gap in quantitative assessment of systemic risk. This study examines the Guangdong Dapeng liquefied natural gas (LNG) pipeline and proposes a multiscale, coupled risk assessment framework based on a hierarchical “region–section–point” approach. At the regional scale, an information-entropy model maps risk distributions and rapidly flags high-risk sections. At the section scale, UAV-based inspection is combined with in situ monitoring to conduct dynamic slope-stability analysis. At the point scale, monitoring data drive a slope–pipeline coupled finite element model that simulates the pipeline’s mechanical response under prospective slope-failure scenarios, enabling early warning of buried-pipeline hazards. Results indicate that the Dapeng pipeline is generally stable. High-risk sections cluster in the Nanshan–Pingshan, Dapeng–Xiasha, and Qingxi–Zhangmutou areas, accounting for 18.9

The large number of fissures developed in loess affect the creep mechanical properties of the soil body, easily triggering geologic disasters such as loess landslides. To gain a comprehensive understanding of the creep characteristics of fissured loess, we used the undisturbed loess from the landslide group in the Heifangtai area of Gansu Province, China, to conduct triaxial creep tests under various prefabricated fissure angles (without fissure, 30 degrees, 45 degrees, 60 degrees, and 90 degrees) and different matric suction conditions. The stress-strain-time characteristics of fissured loess are analyzed, and the long-term strength variation law of fissured loess is determined. The deterioration effect of loess fissures is revealed, and the creep deformation characteristics of fissured loess samples (FLS) are explored. The results show that: (1) The deviatoric stress, confining pressure, and matric suction significantly affect the creep deformation of fissured loess and the duration for the sample to attain steady-state creep. (2) The fissures have a pronounced deteriorating effect on the long-term strength of loess. As the fissure angle increases, the long-term strength of the loess sample initially decreases and subsequently increases, exhibiting a "V" shaped variation, while the cohesion demonstrates a comparable "V" shaped variation. (3) The deterioration coefficient of the fissure initially rises and subsequently declines with increasing confining pressure. (4) The creep deformation characteristics of FLS are categorized into axial deformation, bending deformation, and torsional deformation. Generally, the fissure angle affects the axial strain of the sample; however, an increase in confining pressure weakens the influence degree of the fissure on the deformation. The findings provide new insights into theoretical support for the study of loess mechanics and deformation characteristics in the Loess Plateau region of China. This is significant in elucidating the effect of fissures on the occurrence and development of loess landslide disasters.

Circular agriculture is essential for sustainable food supply, while substantially hindered by spatially decoupled crop-livestock systems. However, the decoupling extent of crop-livestock systems and effectiveness of recoupling strategies remain uncertain due to diverse-resolution investigations. Here we map China's manure phosphorus (P) supply-demand balance from provincial to 1-km resolutions to represent multi-resolution crop-livestock linkages, and identify effective recoupling strategies by mathematical programing models. We find that resolution improvement substantially emphasizes the spatial mismatch of manure P supply-demand and high-density manure P surplus, implying coarse-resolution studies would underestimate the extent and intensity of crop-livestock decoupling whereas overestimating the area of manure P surplus regions. Compared to moderate livestock redistribution, manure transport is generally more effective at national scale for mitigating manure P surplus/deficiency; however, it is less effective in regions with severe manure surplus or large spatial extent. This study deepens the understanding of crop-livestock decoupling and the effectiveness of recoupling strategies.

Landslides are one of the devastating geo-hazards that result in severe casualties in Northwest China (NW China) every year. However, a comprehensive landslide database is yet to be available for quantitatively assessing the distribution of fatal landslides in NW China. To investigate the spatiotemporal characteristics of non-seismically fatal landslides in NW China, we carried out a study using fatal landslides that occurred in Shaanxi province as an example to construct a new database by incorporating data of fatal landslides that occurred in the period between 1996 and 2018. A total of 332 non-seismically fatal landslides that claimed 1132 lives were compiled in this database. Additionally, a thorough study of spatial and temporal variations of fatal landslides reveals that anthropogenic landslides occur approximately evenly throughout the year. Natural fatal landslides, however, rise noticeably in July, August, and September. The spatial distribution analysis showed that fatal landslides in Shaanxi province of China were mainly distributed in the An' kang, Yan'an, and Shangluo regions. Additionally, areas with relatively high relief (46.1 to 123 m), steep-slope topography (19.2 to 26.1 degrees), and intense precipitation (465 to 937 mm) are more vulnerable to naturally-triggered landslides. The spatiotemporal analysis of the fatal landslides revealed increasing trends in zones such as Yan'an and Yulin cities (in northern part), and in An'kang city (in southern part). When combined with other information, the Fatal Landslide Database of Shaanxi Province can be used to provide a guide for risk assessment and spatial planning studies to mitigate geo-hazard risks.

Phosphorus (P) availability is vital for global primary productivity, yet it is often immobilized in soils by redox-inert crystalline iron (oxy)hydroxides. Here we show that diel radial oxygen loss (ROL) from plant roots induces redox fluctuations in the rhizosphere, activating these iron minerals and enhancing P mobilization. Nighttime reduction and daytime oxidation drive the formation of reactive metastable iron phases (RMPs) on root surfaces, forming a redox-active iron plaque. These RMPs undergo rapid dissolution-reformation cycles, facilitating P transfer from soil to porewater for plant uptake. Using multiple aquatic plants from agriculturally developed regions, we demonstrate that ROL broadly enhances soil P availability. In rice paddies, ROL-activated P release accounts for 8.7% of global P fertilizer input, contributing an estimated economic value of USD 0.52 billion annually. Our findings uncover a previously overlooked redox mechanism by which plants enhance P acquisition, with broad implications for nutrient cycling and agricultural sustainability.