Desert steppe ecosystems, characterized by water limitation and high sensitivity to global climate change and anthropogenic disturbance drivers, experience profound alterations in carbon (C) cycling processes driven by the multiplicative interactions among grassland grazing, altered precipitation regimes, and elevated atmospheric nitrogen deposition. However, how historical grazing legacies modulate ecosystem responses to concurrent changes in nitrogen deposition and precipitation regimes remains poorly resolved. To address this, we conducted a field experiment manipulating water and nitrogen addition across grazing intensities (no grazing, light grazing, moderate grazing, heavy grazing) in a Stipa breviflora desert steppe. Over three consecutive growing seasons (2015–2017), we continuously monitored net ecosystem CO₂ exchange (NEE), ecosystem respiration (ER), and gross ecosystem production (GEP) to quantify ecosystem CO₂ fluxes under these interacting global change drivers. Results revealed that water and nitrogen addition did not alter seasonal CO₂ flux dynamics across grazing intensities. Light grazing enhanced ecosystem C sink capacity, whereas heavy grazing reduced NEE and GEP, diminishing C sink strength. Water addition significantly increased CO₂ fluxes, strongly correlated with soil moisture. Nitrogen addition exerted a weak C source effect in a water-deficient year but enhanced the C sink in a water-rich year. Nitrogen plus water addition significantly boosted C sink potential, though this effect diminished along the grazing pressure gradient. Our findings demonstrate that the impacts of climate change on soil C fluxes in desert steppes are mediated by historical grazing intensity. Future manipulative experiments should explicitly incorporate grazing legacy effects, and integrate this factor into C models to generate reliable predictions of grassland C dynamics under global change scenarios.

Manure is essential for integrating crop and livestock systems, but intensive farming has led to a mismatch between massive manure output and its proper use. In China, about 4 billion tons are produced yearly, and raw manure application remains common, posing risks like disease transmission, root damage, soil pollution (e.g., heavy metals, antibiotics), and greenhouse gas emissions. In contrast, well-composted manure improves nutrient supply and soil health while mitigating these risks. This review systematically compares raw and composted manure, analyzing their impacts on soil, water, and air within China’s policy framework (e.g., "Action Plan for Livestock Waste Utilization") and technical standards (e.g., GB/T 25246-2025). while delving into scientific evaluation methods for manure, efficient decomposition processes (including loose stacking, compact stacking, alternating loose-compact stacking, and enhancement techniques such as adding composite microbial agents and biochar), as well as safe application strategies. Key findings indicate that, compared to untreated manure, decomposed manure can increase nitrogen utilization efficiency by 47%, significantly boost soil organic matter (ranging from 122.5% to 354.8%) and humic acid content, and elevate the Shannon–Wiener diversity index of soil microbial communities to 5.6–6.0. Through the adoption of innovative processes such as the "1-Hour Nano-Composting Technology," the decomposition cycle can be substantially shortened, while effectively immobilizing or degrading emerging pollutants such as antibiotics and heavy metals. This paper aims to provide theoretical foundations and practical guidance for promoting the safe and efficient resource utilization of manure.