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.

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.

The Muli mining area on the Qinghai–Tibet Plateau lies within a permafrost region where long-term coal mining has severely degraded native grassland ecosystems. To identify an effective restoration strategy, this study evaluated plant and soil ecological stoichiometry and stoichiometric homeostasis under different combinations of fertilization and seeding rates. A two-factor field experiment was conducted with three fertilization levels (F1–F3) and three seeding rates (S1–S3), using bare slag (BS) and natural grassland (NG) as reference controls. The F3S3 treatment produced the highest aboveground biomass (AGB), representing a 293.55% increase relative to NG. The F2S2 treatment significantly increased plant nitrogen (PN) and phosphorus (PP) contents. In addition, plant carbon-to-nitrogen (PC:PN), carbon-to-phosphorus (PC:PP), and nitrogen-to-phosphorus (PN:PP) ratios under the F2S2, F1S2, and F3S3 treatments, respectively, were closest to those of NG. The PN:PP ratio ranged from 6.05 to 8.20 (<14), indicating that plant growth in the restored plots remained primarily nitrogen-limited. Soil stoichiometric ratios (SOC:TN, SOC:TP, and TN:TP) under the F1S3, F1S1, and F1S2 treatments, respectively, were most similar to those of NG. Principal component analysis (PCA) showed that F3S3 produced the greatest short-term improvement in plant productivity and soil fertility, whereas F2S2 showed the most favorable stoichiometric homeostasis and C:N:P balance relative to natural grassland. Random forest modeling further identified soil total phosphorus, SOC:TN, and available phosphorus as the main factors controlling AGB formation. Overall, F3S3 is suitable for rapid short-term vegetation recovery, whereas F2S2 is more advantageous for long-term restoration when vegetation–soil stoichiometric balance and homeostatic stability are considered. Therefore, restoration projects in similar alpine permafrost mining areas should prioritize the F2S2 treatment to improve both ecological function and system stability.

The Qinghai–Tibet Plateau is a key component of global plateau ecosystems, but the synergistic yield-enhancing mechanism integrating aboveground photosynthetic productivity and belowground increase in soil organic carbon stock under combined green manure and wheat straw incorporation remains unclear. Based on a field experiment established in 2021, four treatments were designed (green manure return (G), straw return (W), combined return (GW), and no-return control (N)) to systematically investigate the effects of return methods on the photosynthetic characteristics, carbon-cycling functional genes, and grain yield of spring wheat. All return treatments significantly increased spring wheat yield, dry matter accumulation, and yield components, with GW showing the greatest effect. The return treatments also increased the net photosynthetic rate, stomatal conductance, transpiration rate, and chlorophyll content, while decreasing intercellular CO₂ concentration. Straw return improved bacterial community evenness; the GW treatment increased microbial β-diversity, enriched Chloroflexi and Fusarium, and constructed a functionally complementary microbial community. Green manure return increased the community richness of the cbbS gene, while straw return reduced the community evenness of the ppdK gene; different return materials directionally reshaped carbon-cycling microbial communities. rbcL was predominantly affiliated with Bradyrhizobium; korA, ppdK, and sdhA were mainly hosted by Nocardioides; Amaricoccus was the dominant genus carrying cbbS, while Flavobacterium prevailed in communities harboring accA and gapA. Co-occurrence network analysis revealed that green manure or straw return alone formed compact networks with high clustering coefficients and short path lengths, dominated by Rokubacteriota and Dormibacterota; the GW network exhibited lower average degree and shorter path length, with Saccharimonadales replacing the original dominant taxa to form a modular structure characterized by low redundancy and high efficiency. Soil organic carbon stock increased under all treatments, with the greatest increment observed under GW. In summary, combined green manure and wheat straw return enhances spring wheat yield by strengthening aboveground photosynthetic performance and optimizing yield components, while simultaneously activating belowground carbon-cycling functional genes, restructuring microbial co-occurrence networks, and promoting soil organic carbon accumulation.