Crop straw returning to the field is an effective practice for straw utilization to improve soil fertility and sustain crop productivity. However, little information is available about the long-term effects of paddy straw return on soil properties and rice yield under a double-rice system. The objectives of this study were to test the hypothesis of the effects of different amounts of paddy straw returned to the field on soil physicochemical properties and rice yield, and to clarify the correlation between crop yield and soil physicochemical properties as well as quick-acting nutrients under different straw-returning modes. The experiment, initiated in the 2005 rice season, utilized “Xiang 45” and “Xiang 13” long-grained rice cultivars within a double-season rice cropping system. Three straw-returning treatments were implemented: rotary tillage with full rice straw incorporation (RTS), incorporation of one-third of the rice straw (1/3RTS), and incorporation of two-thirds of the rice straw (2/3RTS). This study found that among the three straw return rates, 2/3RTS had the most significant impact on soil physicochemical properties. Soil nitrogen content was identified as a crucial factor influencing soil organic carbon (SOC) accumulation, while pH levels significantly affected rice yield. Straw incorporation effectively increased the content and stocks of SOC.

Climate change has emerged as one of the most pressing global challenges in recent decades. Agricultural activities significantly influence climate dynamics, necessitating thorough investigation of their emission patterns. Using the FAO datasets, the objectives of this study were to assess agricultural GHG emissions, identify influencing factors, and explore potential mitigation strategies. The results show that emissions related to crop production are strongly correlated with the yields of predominant crops. Maize production had the largest impact on crop emissions (0.023), followed by potato (0.021) and rice (0.007). Notably, these three crops accounted for substantial portions of total crop-related emissions, with maize contributing 11.70%, potatoes (Solanum tuberosum L.) 10.21%, and rice 9.25%. In the livestock sector, cattle herds generated 10.75% of emissions, with pigs and sheep contributing 9.82% and 10.03%, respectively. Multivariate analysis revealed the cattle/buffalo population as the dominant emission driver (0.32), followed by sheep/goat (0.21) and swine (0.10) populations. Simultaneously, emissions from livestock operations were closely associated with the populations of key livestock species. Thus, from a climate mitigation perspective, prioritizing yield-optimized agronomic approaches for maize and potato cultivation, along with strategic population management of cattle and sheep, represents a critical pathway toward achieving emission reduction targets in global agricultural systems.

Soil organic carbon (SOC) mineralization plays the critical role of regulating carbon sequestration potential. This process is strongly influenced by agricultural practices, particularly tillage regimes and straw management. However, the complex interactions between tillage methods, straw types, and application rates in terms of SOC dynamics, especially in semi-arid agroecosystems like eastern Inner Mongolia, remain poorly understood. In this study, we assessed the combined effects of no tillage (NT) vs. rotary tillage (RT), three straw types (maize/MS, wheat/WS, and oilseed rape/OS), and three application rates (0.4%/low, 0.8%/medium, and 1.2%/high) on SOC concentration and mineralization using controlled laboratory incubation with soils from long-term plots. The key findings revealed that NT significantly increased the SOC concentration in the topsoil (0–20 cm) by an average of 14.5% compared to that in the RT. Notably, combining NT with medium-rate wheat straw (0.8%) resulted in the achievement of the highest SOC accumulation (28.70 g/kg). SOC mineralization increased with straw inputs, exhibiting significant straw type × rate interactions. Oilseed rape straw showed the highest specific mineralization rate (33.9%) at low input, while maize straw mineralized fastest under high input with RT. Therefore, our results demonstrate that combining NT with either 0.8% wheat straw or 1.2% maize straw represents an optimal application strategy, as the SOC concentration is enhanced by 12–18% for effective carbon sequestration in this water-limited semi-arid region. Therefore, optimizing SOC sequestration requires the integration of appropriate crop residue application rates and tillage methods tailored to different cropping systems.

Microbial inoculants are increasingly used in conservation agriculture to enhance soil biological functioning and crop performance, yet their field effectiveness remains variable. This study evaluated how soil resource status, extracellular enzyme activities, and plant traits were associated with maize grain weight per plant under no-tillage straw mulching. A two-year field microplot experiment was conducted in an irrigated semi-arid maize system in northeastern China, comparing four microbial inoculants (M44, CF, SF, and YM) with an uninoculated control (CK). Maize growth and reproductive traits, soil physicochemical properties, and extracellular enzyme activities were measured, with soil variables assessed at depths of 0–10 and 10–20 cm. Microbial inoculation significantly affected aboveground biomass (p = 0.013), hundred-grain weight (p = 0.003), and grain weight per plant (p < 0.001), but not ear weight (p = 0.083). CF and M44 produced the strongest plant-level responses: their two-year mean aboveground biomass exceeded CK by 13.24% and 10.25%, respectively, while grain weight per plant increased by 10.78% and 10.66%. SF showed a weaker grain-weight response but increased β-glucosidase activity by 35.3% relative to CK in 2024, whereas YM increased available phosphorus by 70.8% in 2025 without a comparable grain-weight response. Soil treatment responses varied between years, with significant effects on soil organic carbon and available phosphorus in 2024 and on available phosphorus and soil water content in 2025. Treatment effects on β-glucosidase and cellobiohydrolase were detected only in 2024, while phosphatase was unaffected in either year. The random forest model explained 63.6% of the out-of-bag variation in grain weight per plant (p ≤ 0.001), with plant growth and reproductive traits showing the greatest predictive importance; soil organic carbon, soil water content, and cellobiohydrolase provided additional predictive information. Overall, inoculant responses were product-specific, and variation in grain weight per plant was jointly associated with plant development, soil resource status, and microbial functioning.