Mulching practices are key technologies for addressing soil degradation and increasing crop yields in the dryland farming regions of the Loess Plateau. However, it remains unclear how they synergistically influence soil health and sustainability by regulating soil physical, moisture, and nutrient processes while ensuring yield improvement. In particular, the ecological trade-off effects between crop yield enhancement and soil fertility improvement under different mulching measures still require further research. This study was conducted in 2022 at the Dryland Agriculture Experimental Station of Gansu Academy of Agricultural Sciences to evaluate the effect of straw strip mulching (T_SM), straw crushed mulching (T_SR), and plastic film mulching (T_PM), with flat planting without mulching (T_CK) as the control. The investigation focuses on soil moisture distribution, aggregate composition, soil carbon and nitrogen contents, and yield components in maize fields. The sStudy results showed that all mulching treatments reduced soil bulk density, increased soil porosity, and enhanced soil water content and water storage while reducing evapotranspiration. T_SM most effectively increased soil organic carbon and total nitrogen contents. All mulching treatments improved soil aggregate stability, with T_SM achieving the most significant reduction in soil erodibility by 40%. Compared with T_CK, T_PM, T_SR, and T_SM increased maize grain yield by 71.26%, 44.67%, and 38.04%, respectively. The most influential factors contributing to maize yield are soil water content, soil erodibility, mechanically stable micro-aggregates, and water-stable macro-aggregates. Analysis of the fitting relationship between key influencing factors and yield indicates that soil erodibility demonstrates the optimal fit with yield (R² = 0.73), followed by the fit between soil water content and yield (R² = 0.69). Overall, plastic film mulching primarily enhances short-term yield, while straw strip mulching ensures stable maize production and promotes soil health and sustainable development in dryland farming systems of the Loess Plateau, thus providing a clear theoretical basis for selecting mulching practices based on ecological trade-offs in the Loess Plateau region.

Research on endophytic fungi in desert plants, particularly the epiphytic or endophytic fungi of leaves, remains limited. In the extremely arid regions of northwest China, the ultra-xerophytic desert plant Haloxylon ammodendron harbors white fungi on its assimilating branches during autumn. The hyphae of these fungi intertwine, both internally and externally, comprising superficial, bridging, and endophytic types. The superficial hyphae attach to the surface of the assimilating branches and continuously grow and intersect, forming a thick layer of felt-like hyphae. This thick, felt-like layer of hyphae facilitates the adsorption of atmospheric water vapor on the surface of the hyphae or the assimilating branches, allowing H. ammodendron to capture atmospheric moisture, even under low humidity. Some superficial hyphae penetrate the cuticle into the epidermis, becoming bridging hyphae, which can rapidly transport water from the outside of the epidermis to the inside. The endophytic hyphae shuttle within the epidermis, achieving rapid water transfer within the epidermis of the assimilating branches. The presence of these three types of hyphae not only enables the assimilating branches of H. ammodendron to achieve rapid water absorption and transmission, but also facilitates the uptake of atmospheric water vapor under low humidity conditions. We discuss the mechanism by which the hyphae promote water absorption from the perspectives of hyphal composition, the formation of felt-like structures, and environmental conditions. We consider the presence of fungal hyphae on the surface of the H. ammodendron assimilating branches as an inevitable ecological process in arid environments. This study provides important theoretical insights into the mechanisms underlying the strong drought resistance of desert plants in extremely arid regions and offers strategies for desertification control.

Soil carbon dynamics and microbial communities are critical to soil health. However, the specific effects of mulching on soil microbial community and carbon dynamics in semi-arid rainfed regions remain insufficiently understood. This study aims to identify optimal mulching practices that promote soil carbon sequestration and enhance soil microbial functionality. Mulching treatments were applied in furrows before maize sowing, including black plastic film (TB), white plastic film (TW), straw mulching without sowing (TC), and straw mulching with sowing (TG), and were compared with flat sowing without mulching (TN). Results revealed that TG treatment promoted soil carbon dynamics by increasing total carbon (9%), organic carbon (19%), microbial biomass carbon (100%), easily oxidized carbon (10%), particulate-associated carbon (77%), carbon stability index (7%), active carbon fraction (45%), dissolved carbon proportion (30%), and microbial quotient (34%) compared to TN. A higher abundance and composition of bacterial communities were observed compared to fungal communities. The highest bacterial abundance of Kaistobacter, iii1_15, Sinobacteraceae, and Xanthomonadaceae, and fungal abundance of unspecified fungi, Laiosphaeriaceae, and Sordariomycetes, with the dominant aerobic respiration metabolic pathway involved in organic matter decomposition, were observed in TG and TC. The results indicated that TG treatment most effectively promoted carbon fractions and microbial activity that could strengthen soil health.

Soil nitrogen availability is a major constraint to crop productivity in rainfed arid and semi-arid regions. The influence of straw strip mulching on nitrogen availability and transformation across soil layers remains unclear. This study investigates the effect of straw strip mulching on soil nitrogen dynamics and crop-specific variation in wheat- and potato-cultivated soils under rainfed semi-arid conditions. This study consisted of five mulching treatments, including without mulching (Tck), black plastic film mulching (Tp), straw strip mulching (Tss), plant strip without mulch (Tps), and composite strip of straw strip mulching and plant strip without mulch (Tcs) applied in wheat and potato cultivation during 2019 and 2020, and soil nitrogen fractions were determined across different soil depths. Tss mulching showed the highest increase in urease activity (48%), nitrite reductase activity (48%), microbial biomass nitrogen (52%), NH₄ (11%), acid-hydrolyzed total nitrogen (10%), acid-soluble NH₄ (6%), acid-hydrolyzed amino sugar (16%) and acid-hydrolyzable unknown nitrogen (59%) relative to Tck without mulching. While total nitrogen (11%) and acid-hydrolyzed amino acid (9%) were highest in the Tps treatment compared to Tck treatment, the mulching treatment had no significant effect on soil organic nitrogen-derived functional traits. Across all treatments, the 0–20 cm soil layer consistently showed the highest concentrations of observed soil traits, which declined with increasing soil depth. Furthermore, potato-cultivated soils showed consistently higher concentrations of these traits than wheat-cultivated soils, and the concentrations of these traits in 2020 exceeded those observed in 2019. This study highlights that maize straw mulching in strips significantly promotes soil organic nitrogen fractions, particularly in the upper soil layers, and promotes higher nitrogen availability in potato than in wheat-cultivated soils, and is recommended as an effective soil management practice to improve soil nitrogen availability in rainfed semi-arid Loess Plateau conditions.

Maize/soybean intercropping systems improve resource use efficiency through interspecific complementarity. However, the regulatory mechanisms by which the partial replacement of chemical nitrogen fertilizer by organic fertilizer and biofertilizer affects crop growth and productivity in maize/soybean systems remain unclear. A two-year field experiment (2024–2025) was conducted in the Hexi oasis irrigation district of Zhangye, Northwest China. The main plots were assigned to fertilization regimes (conventional nitrogen, N₁; reduced nitrogen, N₂; organic substitution, ON₂; and biofertilizer substitution, BN₂), and the subplots were assigned to cropping systems (maize monoculture, soybean monoculture, and maize/soybean intercropping). A logistic growth model was used to simulate dry matter accumulation, and the land equivalent ratio (LER), net effect (NE), complementarity effect (CE), and selection effect (SE) were employed to evaluate intercropping advantage. Mantel analysis was applied to analyze relationships between crop growth parameters and system grain yield. Study results showed that cropping system fertilization regime, year, and their multiple interactions had significant effects on maize, soybean, and system grain yields (p < 0.001). Under all fertilization treatments, the LER of the maize/soybean intercropping system was greater than 1, indicating that intercropping had higher land-use efficiency than monoculture. Compared to the weighted mean of monocultures, ON₂ enhanced intercropping grain yield by 25.30% over two years driven primarily by positive SE. Compared to conventional N practice, ON₂ increased intercropped maize grain yield by 19.98% and 12.40% in 2024 and 2025, respectively, while BN₂ enhanced intercropped soybean yield by 22.60% in 2025. Together, system grain yield followed the rank ON₂ > BN₂ > N₁ > N₂. Mantel tests further revealed that maize maximum biomass potential (Y_max) was highly significantly and positively correlated with system grain yield (p < 0.01), and maximum growth rate (I_max) was significantly positively correlated (p < 0.05), whereas soybean growth parameters showed no significant correlation with system yield. Overall, partial substitution of chemical fertilizer with organic fertilizer enhances maize biomass accumulation and fosters positive interspecific interactions, thereby increasing grain yield in maize/soybean intercropping. These findings provide a practical basis for reducing chemical fertilizer use while maintaining productive and sustainable cropping systems.