Soil microorganisms, as a vital part of terrestrial ecosystems, play a key role in sustaining essential soil functions. However, the impact of cultivated land (CL) on soil quality and microbial communities compared to other land-use types is still unclear. This study investigated the soil quality index (SQI) along with bacterial and fungal communities across various land-use types, including abandoned land, cultivated land, forest land, and grassland, in the Longzhong region of the Loess Plateau. The results showed that CL had the lowest SQI, but the diversity of soil bacterial and fungal communities in CL was significantly higher than that of other land-use types. The relative abundance of Ascomycota in CL fungal communities is significantly higher than that of other land-use types. Soil water content, organic matter, alkaline nitrogen, total nitrogen, and nitrate nitrogen all have an impact on soil bacterial and fungal communities in CL. The diversity of soil bacterial and fungal communities is mainly influenced by pH, nitrate nitrogen, and available phosphorus. This study emphasizes the impact of human activities such as tillage on soil quality, as well as the structure and diversity of soil microbial communities, in cultivated land compared to other different land-use methods.

The impact of various crop rotation systems on the potential for soil carbon sequestration and stoichiometric characteristics is not yet fully understood, which poses challenges for effective land management and utilization. This study selected three typical crop rotation methods in the Longzhong Loess Plateau: maize–alfalfa rotation (MA), maize–sainfoin rotation (MS), and maize–wheat rotation (MW). Soil physical and chemical indices were measured, and the soil carbon density and soil stoichiometry were calculated and analyzed. The results show that the soil C/N of the surface soils was low across the rotation methods, indicating a rapid rate of organic matter decomposition and mineralization, which may hinder soil nutrient accumulation. The soil N/P was found to be lower than the national average of 8.0, indicating that nitrogen is a limited nutrient in the soil under the three crop rotation systems in this region. The soil total nitrogen content can be increased by rotation with leguminous forage. Sainfoin rotation can enhance the soil total carbon and organic carbon content, thereby improving the soil’s carbon sequestration potential. The research findings provide a theoretical foundation for the selection of appropriate rotation methods and the maintenance of the stability of agricultural ecosystems in semi-arid regions.

As the ecological security barrier in northwestern China, understanding how natural grassland (NG) utilization pattern transformation in the northern Qilian foothills affects soil quality and ecosystem multifunctionality supports regional ecosystem management. The study compared soil chemical and biological properties, soil quality index (SQI), and soil ecosystem multifunctionality (SMF) among four grassland utilization patterns in the northern foothills of the Qilian Mountains, Gansu Province, China. Soil samples were collected in early October 2024 following crop harvest from the following systems: traditionally grazed NG, monocropping Hordeum vulgare (barley; MHV), monocropping Avena sativa (oat; MAS), and Hippophae rhamnoides shrubland (sea buckthorn; HRS). The results showed that compared with NG, SQI was decreased by 52.69% (p = 0.000059) under MHV treatment and by 18.78% (p = 0.03) under MAS treatment, while HRS did not have a significant reduction in SQI. Under the three patterns of transformative utilization of NG, SMF followed the order of HRS (0.11) > MAS (−0.06) > MHV (−0.51). Overall, the establishment of restoration vegetation (sea buckthorn shrubland) retained SQI under different grassland utilization patterns in the study area, whereas long-term monocropping resulted in significant reductions in SQI and SMF due to compromised chemical and biological properties.