The practice of straw returning to agricultural fields (SRF) affects crop yields and greenhouse gas (GHG) emissions. However, the responses of crop yields and GHG emissions vary significantly due to diverse climatic conditions, soil conditions, and field management practices. In this study, we conducted a meta-analysis to assess the effects of SRF on the crop yield and GHG emissions from staple crops in China. Our results indicate that the average increment in the yield of three staple crops is 13.00% with SRF. Moreover, SRF decreased the N₂O emissions compared to those without straw returning in regions with 800–1200 mm of MAP, SOC > 20 g kg^–1, 0.9–1.5 g kg^–1 TN, pHs of 6.5–7.5, and a SRF duration < 3 years, in rice cultivation systems, and with partial SRF. However, irrespective of the climatic conditions, soil properties, or field management practices, SRF increased the CO₂ emissions compared to those without straw returning. Additionally, while SRF significantly increased the CH₄ emissions in paddy fields, it had no discernible effect on the CH₄ uptake in upland fields compared to that without straw returning. These findings offer valuable insights for optimizing straw management practices and reducing GHG emissions in farmland ecosystems.

Rapid urbanization enhances the necessity of exploring sustainable development paths to achieve ecological and carbon storage protection. This study takes Zhengzhou, one of the national central cities in China, as a case to investigate the dynamic correlation between urbanization (UR) and carbon storage (CS). The PLUS and InVEST models were employed to simulate land use and carbon storage dynamics under natural development, cultivated land protection, and ecological protection scenarios for 2030 and 2040. This was also complemented by elasticity analysis of UR, construction land expansion (CEL), and CS. The results show that from 2000 to 2020, cultivated land declined by 15.33%, while construction land expanded by 13.31%. By 2030, construction land growth is expected to be 7.34%, 2.87%, and 4.96% across scenarios, with cultivated land of −6.96%, −2.36%, and −4.78%, respectively. Carbon storage in 2030 decreases under all scenarios (5.181 × 10⁷ t, 5.235 × 10⁷ t, 5.209 × 10⁷ t) but stabilizes by 2040, with ecological protection enhancing forest/water bodies and mitigating losses. Elasticity analysis reveals that unconstrained elasticity coefficient significantly exacerbates carbon losses, while policy interventions reduce losses through expansion control and carbon sequestration. Integrating land use policies to balance farmland protection, ecological restoration, and low-carbon urban expansion is critical for sustainable megacity development and a scalable framework for carbon governance.

Film mulching (FM) has the positive effectiveness of increasing production and retaining soil water, which indicated that film mulching is a widespread technique. However, the agreement about the effects on cotton yield and water use efficiency (WUE) has not yet been established. We collected 222 yield and 55 WUE observations from 68 articles and used meta-analysis to investigate whether FM is effective on cotton yield and WUE. FM markedly enhanced cotton yield and WUE by 30.11% and 40.03%, respectively, in comparison to no mulching. Importantly, FM performed better at mean annual precipitation (MAP) < 200 mm and mean annual temperature (MAT) < 12 ℃. Higher cotton yield and WUE under FM was observed in medium and fine-textured soils with soil bulk density (BD) < 1.4 g cm⁻³, soil organic matter (SOM) < 20 g kg⁻¹ and total nitrogen (TN) < 0.8 g kg⁻¹. Additionally, FM achieved higher cotton yield and WUE at nitrogen fertilizer application rate (NFAR) < 250 kg ha⁻¹, phosphorus fertilizer application rate (PFAR) < 125 kg ha⁻¹ and potassium fertilizer application rate (KFAR) ≤ 380 kg ha⁻¹, respectively. The equally space planting (ESP) with flat planting with film mulching (FPFM) was more beneficial for cotton yield and WUE. In conclusion, our findings suggest FM can enhance higher cotton yield and WUE simultaneously, and the above results can provide practical guidance and reduce the adverse environmental effects under FM.