Microbial agents play a crucial role in improving soil quality, increasing soil fertility, enhancing crop yields, and reducing the incidence of diseases. The ecological benefits of these products contribute to environmental protection and to the promotion of sustainable agricultural development. Since the beginning of the 21st century, research in the academic community on the use of microbial agents for soil improvement has increased, yet a systematic summary of the progress in this field is lacking. In this paper, we review trends in microbial agent applications, focusing on their classification, mechanisms of action, and practical implementations. To achieve this, we conduct a bibliometric analysis based on the SCI-EXPANDED database of the Web of Science, using tools such as VOSviewer for visualization. We focus on microbial agents for soil improvement and analyze publication trends, research hotspots, and annual variations in relevant studies published between 2003 and 2024. The results show that (1) the number of publications on microbial soil improvement has steadily increased over the years, indicating that the academic community has maintained a high level of interest in this field. Keywords such as “soil”, “diversity”, “carbon”, and “nitrogen” have been central research hotspots in the past 20 years. The research has been highly concentrated in a few countries, including China and the United States, as well as in key institutions such as the Chinese Academy of Sciences and the United States Department of Agriculture. (2) We further analyze the principles governing microbial agent efficacy, address limitations in their application, and propose strategies to advance research in this field. Finally, several suggestions are proposed to promote the further development of research on microbial agents for soil improvement.

Vegetation restoration plays a crucial role in conserving soil and water, as well as rehabilitating ecosystems, by enhancing soil properties and vegetation attributes. The evaluation of the ecological consequences among different vegetation restoration types can be achieved by clarifying the impacts on carbon, water and nutrient storages. In this study, we selected four typical vegetation restoration types (Pinus tabuliformis forest (PTF), Platycladus orientalis forest (POF) and Robinia pseudoacacia forest (RPF) as typical planted forests, and the natural secondary forest (NSF) as the control treatment) in the eastern Loess Plateau of China. The soil properties (at 0–200 cm depth) and vegetation attributes (including arborous, shrubs and herbaceous plants) were measured, as well as calculated soil carbon, water and nutrient storages, with a total of 1600 soil samples and 180 vegetation survey plots. The partial redundancy analysis (pRDA) and correlation analysis were also used to analyze the contributions and relationships among environmental factors, soil eco-hydrology and nutrient supplement services in different forestry ecosystems. The results indicate the following: (1) NSF has the lowest soil bulk density (1.21 ± 0.184 g·cm⁻³). Soil properties varied significantly at vertical scales, and had obvious surface accumulation. (2) Soil moisture storages were better in natural forests than those in planted forests, with more drastic changes in soil moisture dynamics. (3) The soil carbon, nitrogen, and phosphorus storages significantly differed among four vegetation types, with the highest carbon storages in PTF (207.75 ± 0.674 t·ha⁻¹), the highest nitrogen storages in POF (5.54 t·ha⁻¹), and the highest phosphorus storages in RPF (4.33 t·ha⁻¹), respectively. (4) Soil carbon storages depend primarily on the coupling effect of soil properties and precipitation, while nutrient storage is mainly influenced by soil properties. The results quantify the significant differences in soil water, carbon, and nutrient storage across various vegetation restoration types, and reveal the individual and combined contributions of environmental factors, providing new insights into the mechanisms driving these differences. These findings offer practical guidance for the sustainable management of forest ecosystems and the optimization of ecological restoration strategies on the Loess Plateau.

The Hetao Irrigation District is an important arid-oasis agricultural system in the Yellow River Basin, where water scarcity has become a major constraint on high-quality regional development and irrigation water use dominates the district’s water-use structure. Irrigation water resources carrying capacity represents the application of the broader concept of water resources carrying capacity to irrigation systems. Existing studies have largely overlooked long-term assessments of irrigation water resources carrying capacity and the identification of its dominant patterns of variation at the irrigation-district scale. This study aimed to evaluate irrigation water resources carrying capacity in the Hetao Irrigation District from 2001 to 2023 and identify its dominant patterns of variation. An evaluation indicator system was developed, and a TOPSIS model incorporating combined subjective–objective weighting was used to assess long-term changes in carrying status, while principal component analysis was applied to identify the dominant patterns of variation. The results showed that improvement in the irrigation water-use efficiency subsystem partially offset the adverse effects of the decline in the water availability subsystem, resulting in an overall improvement in carrying status. Linhe District ranked highest among the county-level units, whereas Dengkou County ranked lowest. The variation in carrying capacity was summarized into three dimensions: joint variation in water availability and water-use scale; a mixed pattern linking irrigation water-use intensity, the degree of water resource utilization, and groundwater conditions; and variation in effective irrigation coverage. By integrating long-term carrying-status assessment with the identification of dominant patterns of variation, this study reveals a compensatory relationship between improved irrigation water-use efficiency and declining water availability, thereby providing a new perspective on carrying-status evolution at the irrigation-district scale.