In order to systematically and objectively assess the research status and development trends on the utilization of rice straw, and provide a reference for the efficient utilization of rice straw in China, the literature research was conducted in this field from 1995 to 2024 based on the core database of Web of Science using the Citespace. The number of annual published literatures, the main published countries, research institutions, keyword co-occurrence network, and keyword clustering were visually analysed. On this basis, the current status, key common technologies, and the carbon sequestration and emission reduction potential of rice straw utilization in China were systematically summarized, and future research trends and priorities were also proposed. The annual publications had showed a continuous upward trend in the field of global rice straw utilization, and the number of publications showed an exponential growth trend after 2008, indicating that this research field had received extensive attention world widely. As a major rice producer in the world, China had a strong scientific research force and strong influence in this research field, with the highest citation frequency and H-index index of publications. Domestic research institutions such as the Chinese Academy of Sciences and the Chinese Academy of Agricultural Sciences had close cooperation relationships with domestic and foreign institutions. In the past 30 years, the impact of rice straw utilization on rice growth and yield, soil carbon and nitrogen nutrients, and greenhouse gas emissions were the research hotspots in this field. The accumulation, biological properties, and toxicity of heavy metals (such as arsenic, cadmium, lead, etc.) in soil by rice straw returning or rice straw biochar returning was also a hot topic. In addition, the anaerobic fermentation and biogas production during the pretreatment process of rice straw had gradually increased attentions. Recently, the greenhouse gas emissions and global warming potential after rice straw utilization were the major research focus. Based on China's national conditions, this study conducted an in-depth analysis of the current status and key common technologies of the comprehensive utilization pattern of rice straw characterized by “agricultural application as the priority and simultaneous development of five utilization pathways” (fertilization, feedification, fuelification, substrate application, and raw material utilization). According to statistical analysis in 2016, the main utilization methods of rice straw were fertilization and fuel utilization, accounting for 69.0% and 14.7% respectively, following by the feed utilization, base material utilization, and fuel utilization, which accounted for 8.6%, 3.7%, and 4.0% respectively. Compared with direct incineration, the potential contribution of five material utilization to greenhouse gas emission reduction and carbon sequestration were greater. The carbon sequestration and emission reduction potential of different utilization methods were also evaluated. The research proposed that future efforts should focus on expanding diversified carbon sequestration and emission reduction technologies, innovating high-value and large-scale utilization pathways, and establishing intelligent monitoring, traceability, and decision-making systems. These initiatives would advance research on the high-value and intelligent utilization of rice straw through interdisciplinary approaches. This study provided critical decision-making references for promoting the recycling of straw resources, facilitating green and low-carbon transformation in agriculture, and supporting the achievement of national carbon peak and carbon neutrality goals.

The contour ridge tillage had a certain effect on reducing soil organic carbon (SOC) loss in sloping cropland, but the unique long and slow topography would interact with contour ridge cropping on the spatial differentiation of SOC in sloping cropland of the black area. However, the risk of SOC loss caused by this interaction has not attracted enough attention yet. In this study, Hongxing Farm of Beian Branch, Heihe City, Heilongjiang Province, a typical black soil area, was taken as the study area, and the two directions of the contour ridge cropping and longitudinal waterline direction were divided according to the study purpose under the contour ridge cropping measure, and a total of 75 sample sizes were taken in the two directions. The geographic detector model as well as one-way ANOVA and Pearson's correlation analysis were conducted to explore the spatial differentiation of SOC and its interactive effects. In the contour ridge tillage direction, SOC content showed a trend of gradual increase from the top position of the slope to the waterline in the ridge furrow; and it showed a trend of increase and then decrease from the top position of the slope to the waterline in the ridge platform. Along the longitudinal waterline direction, the SOC content showed a trend of increasing from lower to upper position in the ridges, and it showed a trend of increasing and then decreasing in the ridge platform. Soil organic carbon content was significantly greater in ridges than in furrows (P < 0.05). The soil organic carbon content of the upper was still significantly different from the lower due to the waterline created by the broken ridge (P < 0.05). Spatial differentiation of soil organic carbon resulted in greater spatial variability of SOC along the direction of contour ridge cropping and less spatial variability along the direction of the longitudinal waterline. Pearson's correlation analysis showed that organic carbon was significantly negatively correlated with the erodibility factor (correlation coefficient of -0.228 and -0.238, P < 0.05 for furrow and platform, respectively), and that β-glucosidase (BG) and microbial biomass carbon (MBC), which are related to carbon cycling, were highly significantly positively correlated with the erodibility factor in furrow (correlation coefficient of 0.398 and 0.676, P < 0.01). Geographic detector analysis showed that, among the single factors, the longitudinal waterline had the greatest effect on soil organic carbon differentiation, and its explanatory rate reached more than 61% and 52% for ridges and ridgetops, respectively; among the two factors, the interaction between longitudinal waterline and other factors had the greatest effect, and all of them strengthened the explanatory power of soil organic carbon, especially the interaction between longitudinal waterline and topography was the most obvious, and the explanatory rate in ridges and ridgetops both reached more than 90%. The spatial differentiation of SOC in sloping cropland in the black soil area was mainly affected by the interaction between the longitudinal waterline and topography on the downslope. Although the contour ridge tillage was able to intercept runoff, the broken ridges generated by the influence of the topography on the long and gentle slopes will exacerbate the loss of SOC induced by soil erosion. Therefore, it is suggested to consider the joint influence of contour ridges and topography at the same time in the management of black soil slope cropland, and to pay enough attention to the potential risk of contour ridges, so as to achieve the optimized effect for erosion prevention.

Agricultural non-point source pollution has been the leading cause of water quality in recent years. The prevention and control of non-point source pollution can improve the ecological environment quality in the green transformation of agricultural development and rural revitalization. However, agricultural non-point source pollution has been the prominent difficulty for the water environment protection with the effective control of industrial and urban point source pollution. Particularly, water environment protection is still remained elusive in the watershed scale. This study aimed to review the current situation to determine the main bottlenecks in the prevention and control of agricultural non-point source pollution. Key measures were also explored in the whole factors and chain. The optimization and maintenance paths were proposed for the typical pilot areas in the Yangtze River Basin. Firstly, the agricultural non-point source pollution was reduced with a significant decrease in the water pollution emissions. But the emissions proportion was also remained high. Secondly, the bottlenecks were clarified using various operations, such as data collection, on-site research, and expert discussions, in term of governance entities, investment factors, technological systems and industrial chains. The single governance body, scattered departmental functions, and independent governance fields were the critical factors for the main body of agricultural non-point source pollution control. It was very necessary to construct the digital platform for the investment elements, such as technological support, regulatory system, financial investment and ecological compensation. The linear production model of "resource-product-waste discharge" was also needed to gradually shift towards an ecological circular industrial chain with the multi-dimensional and multi-levels. Thirdly, the connotation was defined in the entire element and chain of integrated system. Among them, the integrated system was referred to the top-level design and systematic promotion from the perspective of development concepts and ideas. Whole factors were referred to the aggregation of funds, integrated application of technology, development of governance entities, and digital intensive empowerment. Full chain was to unblock the ecological cycle of the front, middle, and end of agricultural non-point source pollution control, in order to construct a multi-scale agricultural ecosystem with the large, medium, and small cycles, and then form an integrated pattern of production life ecology. Fourthly, the typical cases were selected from the national agricultural green development pilot zones. The implementation path and application effectiveness was elaborated for the prevention and control of agricultural non-point source pollution with the "whole factors" and "whole chain" in an integrated system. Three types of work were carried out in the typical cases: "integrated organizational system" on the grid scale, "whole chain" on the specialized extension, and "whole factors" on the pollution prevention and control in various aspects. The finding can provide the support to the prevention and control of non-point source pollution in the green transformation of modern agriculture.