Oases in arid regions are crucial for sustaining agricultural production and ecological stability, yet few studies have simultaneously examined the coupled dynamics of land use/cover change (LUCC), carbon emissions, and ecosystem service value (ESV) at the oasis–agricultural scale. This gap limits our understanding of how different land use trajectories shape trade-offs between carbon processes and ecosystem services in fragile arid ecosystems. This study examines the spatiotemporal interactions between land use carbon emissions and ESV from 1990 to 2020 in the Wensu Oasis, Northwest China, and predicts their future trajectories under four development scenarios. Multi-period remote sensing data, combined with the carbon emission coefficient method, modified equivalent factor method, spatial autocorrelation analysis, the coupling coordination degree model, and the PLUS model, were employed to quantify LUCC patterns, carbon emission intensity, ESV, and its coupling relationships. The results indicated that (1) cultivated land, construction land, and unused land expanded continuously (by 974.56, 66.77, and 1899.36 km²), while grassland, forests, and water bodies declined (by 1363.93, 77.92, and 1498.83 km²), with the most pronounced changes occurring between 2000 and 2010; (2) carbon emission intensity increased steadily—from 23.90 × 10⁴ t in 1990 to 169.17 × 10⁴ t in 2020—primarily driven by construction land expansion—whereas total ESV declined by 46.37%, with water and grassland losses contributing substantially; (3) carbon emission intensity and ESV exhibited a significant negative spatial correlation, and the coupling coordination degree remained low, following a “high in the north, low in the south” distribution; and (4) scenario simulations for 2030–2050 suggested that this negative correlation and low coordination will persist, with only the ecological protection scenario (EPS) showing potential to enhance both carbon sequestration and ESV. Based on spatial clustering patterns and scenario outcomes, we recommend spatially differentiated land use regulation and prioritizing EPS measures, including glacier and wetland conservation, adoption of water-saving irrigation technologies, development of agroforestry systems, and renewable energy utilization on unused land. By explicitly linking LUCC-driven carbon–ESV interactions with scenario-based prediction and evaluation, this study provides new insights into oasis sustainability, offers a scientific basis for balancing agricultural production with ecological protection in the oasis of the arid region, and informs China’s dual-carbon strategy, as well as the Sustainable Development Goals.

Quantifying the impacts and contributions of nitrogen (N), phosphorus (P), and potassium (K) fertilizer management on the annual and cutting cycle yields of alfalfa can provide guidance for alfalfa cultivation. In this study, 597 sets of alfalfa yield data from the arid and semi-arid regions of China were collected and grouped according to the N, P, K, and NPK rates. Statistical and meta-analyses were employed to explore the response of alfalfa yield to fertilization management. The results indicated that the annual and cutting cycle yields of alfalfa increased and then decreased as the N rate increased; meanwhile, the annual yield increased with the P and K rates, and the cutting cycle yield decreased with increased cutting cycles under P and K treatments. The alfalfa yield at the first cutting cycle was about 30% of the annual yield in the arid and semi-arid regions of China. Moreover, the annual yield increased and then decreased as the NPK rate increased. The Aggregated Boosted Tree (ABT) algorithm-based analysis showed that the NPK rate had the greatest contribution to the annual yield (37.61%), followed by the application rates of P (24.50%), N (22.55%), and K (15.34%). The impacts of the P/NPK, N/NPK, and K/NPK ratios on the annual yield were 38.64%, 31.71%, and 27.65%, respectively. Additionally, an NPK amount > 225–310 kg/ha and ratios of N, P, and K of 14.28–27.72%, 36.36–50%, and below 25%, respectively, resulted in the highest increase in alfalfa yield. This is recommended as the optimal fertilization practice to obtain high alfalfa yields and improve fertilizer use efficiency in the arid and semi-arid regions of China.