Nitrogen (N) and water irrigation are two vital factors influencing the agriculture sustainability in various regions across the world, such as the North China Plain (NCP). Exploring optimal N application and water-efficient irrigation methods are needed for achieving greater crop productivity benefits and increasing the efficiency of inputs (N and water) in winter wheat (Triticum aestivum L.) production in the NCP. For this reason, we conducted a two-year field experiment with four N application rates interacting with three irrigation methods to examine the effects of N fertilization and water-efficient irrigation on grain yield, biomass production, economic benefits, and N- and water-use efficiencies of winter wheat in the NCP. The optimal N fertilization rate was ≈200 kg N ha⁻¹, achieving a high grain yield of winter wheat (≈6000 kg ha⁻¹). At this N dose, the highest net economic benefit was also achieved by the local farmer due to the increased grain yield, which was accompanied by more water-efficient irrigation. N recovery efficiency, agronomy efficiency, and the partial factor productivity of wheat decreased sharply with the N application rate. Water-use efficiency was significantly increased through drip irrigation and sprinkler irrigation. Considering the wheat productivity, input (N and water) efficiencies, and economic performance, water-efficient irrigation accompanied with an N application rate of 200 kg N ha⁻¹ is optimal for achieving high economic returns for local farmers in the NCP.

Biochar application has the potential for mitigating N₂O emissions from agricultural soils and has been suggested as a management practice to ameliorate soil fertility and increase crop productivity. Nevertheless, the influence of biochar addition on N₂O emissions from soils with different pH levels is not yet clear, which results in a poor understanding of the mechanisms regarding biochar application to soil N₂O mitigation. A 40-day incubation experiment was carried out in the present study to investigate the impact of biochar on N₂O emissions from soils with different natural pH. Four treatments (control, nitrogen fertilizer application, biochar amendment, and N plus biochar amendment) were set up separately in soils with three different natural pH levels (acidic vegetable soil, neutral rice soil, and alkaline soil). Our results showed that adding biochar significantly decreased N₂O emissions by 20.8% and 47.6% in acidic vegetable soil for both N and no N addition treatments, respectively. For neutral and alkaline soils, the reduction of N₂O emissions by biochar amendment was only significant for N addition treatments in alkaline soil. Soil pH and NO₃⁻-N concentration were significantly affected by biochar amendment (soil pH increased by 1.43–1.56, 0.57–0.70, and 0.29–0.37 units for acidic vegetable soil, neutral rice soil, and alkaline soil, respectively). Thus, biochar amendment could be used as an effective management practice for mitigating N₂O emissions from acidic and alkaline soils.

The effects of nighttime warming and rainfall increasing on crop productivity and soil greenhouse gas emissions are few studied. This study was conducted with a field experiment to investigate the effects of nighttime warming, rainfall increasing and their interaction on wheat grain yield, methane (CH₄) and nitrous oxide (N₂O) emissions during a winter wheat growing season in the North China Plain (NCP). The results showed that nighttime warming and rainfall increasing significantly altered soil temperature and moisture, and thus the CH₄and N₂O emissions from the soil. Nighttime warming significantly promoted soil CH₄uptake by 21.2% and increased soil N₂O emissions by 22.4%. Rainfall increasing stimulated soil N₂O emissions by 15.7% but decreased soil CH₄uptake by 18.6%. Nighttime warming significantly decreased wheat yield by 5.5%, while rainfall increasing enhanced wheat yield by 4.0%. The results indicate that the positive effect of nighttime warming on CH₄uptake and negative effect on wheat yield can be offset by rainfall increasing in the NCP. Generally, rainfall increasing significantly raised the global warming potential and greenhouse gas intensity induced by CH₄and N₂O emissions. Overall, this study improves our understanding of agroecosystem C and N cycling in response to nighttime warming and rainfall increasing under future climate change.

Reconciling agricultural productivity with greenhouse gas (GHG) mitigation remains a pivotal challenge for achieving climate-smart food systems. This study evaluates the capacity of legume-based crop rotations to balance economic viability, yield stability, and GHG reduction in the North China Plain. A two-year randomized complete block field experiment compared six cropping systems: conventional wheat–maize (WM) rotations and legume-integrated systems (wheat–soybean, WS; wheat–soybean–maize, WSM), under fertilized and unfertilized regimes. Results revealed that nitrogen fertilization increased cumulative N₂O emissions and global warming potential (GWP), with seasonal peaks occurring post-fertilization. Legume systems enhanced CH₄ uptake but showed no significant effect on N₂O emissions compared to conventional systems. N₂O fluxes correlated positively with soil moisture and soil temperature, while CH₄ uptake increased with soil moisture alone. Soybean phases reduced short-term yields by 32–52% relative to the maize yield of conventional systems, but boosted subsequent wheat/maize productivity by 2–47% through hydraulic redistribution and N priming. The wheat–soybean rotation with 200 kg N ha⁻¹ (WS200) achieved optimal sustainability, delivering the highest net profit (8061.56 USD ha⁻¹) alongside a 9% reduction in global warming potential (3980.21 kg CO_2-eq ha⁻¹) versus conventional systems. These findings provide actionable insights for sustainable intensification in global cereal systems, demonstrating that strategic legume integration can advance both food security and climate goals.

Context: Overuse of N fertiliser in vegetable cropping systems is known to release of nitric and nitrous oxide to the atmosphere in China. Optimisation of N fertilisation regimes has the potential to mitigate NO and N2O emissions from these N-rich systems. Aims: We investigated the effects of different N fertilisation regimes on NO and N2O emissions, and vegetable yields, with particular efforts to estimate annual direct emission factors of NO and N2O under different N fertilisation regimes in greenhouse vegetable fields. Methods: Annual NO and N2O fluxes were taken simultaneously using the static chamber-based method from a greenhouse vegetable system in south-east China with four N fertiliser treatments: (1) no N fertiliser (control); (2) chemical N fertiliser application (CF); (3) organic N fertiliser application (OF); and (4) organic-chemical mixed N fertiliser application (MF). Key results: N fertilisers significantly increased NO and N2O emissions. Direct emission factors of N fertiliser for NO and N2O were the largest for MF, with an average of 0.99% and 0.67%, respectively. Vegetable yields were only significantly enhanced under OF treatment. Conclusions: Relative to the use of chemical N fertiliser, the application of organic-chemical mixed N fertiliser showed not to be effective for mitigating NO and N2O emissions. Instead, sole application of organic N fertiliser was a viable option to enhance vegetable yields but without increasing NO and N2O emissions in greenhouse vegetable systems. Implications: Substituting the use of chemical N fertiliser with organic N fertiliser input could benefitvegetable production but without stimulating NO and N2O emissions from vegetable cropping systems in sub-tropical China.

Microplastics (MPs), biochar, and earthworms are critical yet understudied drivers of greenhouse gas (GHG) emissions in agricultural soils. However, limited research has explored the interactive effects of these factors on soil GHG emissions and soil carbon and nitrogen cycling. Here, we conducted a full-factorial mesocosm experiment (2×2×2 design) to assess the individual and combined influences of PVC microplastics (1% w/w), biochar (1% w/w), and the epigeic earthworm on carbon dioxide (CO₂), nitrous oxide (N₂O), and methane (CH₄) emissions in a sandy-loam soil. The results revealed that MPs increased soil CO₂ emissions while suppressing N₂O and CH₄ emissions. Earthworms elevated CO₂ and N₂O emissions by 42.3% and 27.3%, respectively. Biochar amplified CO₂ release by 20.6% and reduced N₂O by 26.1%. The interaction between MPs and earthworms significantly influenced CO₂ emissions and the global warming potential (GWP). Both MPs and biochar significantly enhanced earthworm survival rates by 24-33% but did not affect individual biomass. Soil properties were partially influenced by the individual or combined effects of MPs, biochar, and earthworms. Overall, these results underscore the need for integrated amendment strategies to mitigate GHG emissions in MPcontaminated agroecosystems, balancing carbon sequestration priorities with soil health preservation.