Background: Environmental stress is a crucial factor restricting plant growth as well as crop productivity, thus influencing the agricultural sustainability. Biochar addition is proposed as an effective management to improve crop performance. However, there were few studies focused on the effect of biochar addition on crop growth and productivity under interactive effect of abiotic stress (e.g., drought and salinity). This study was conducted with a pot experiment to investigate the interaction effects of drought and salinity stress on soybean yield, leaf gaseous exchange and water use efficiency (WUE) under biochar addition. Results: Drought and salinity stress significantly depressed soybean phenology (e.g. flowering time) and all the leaf gas exchange parameters, but had inconsistent effects on soybean root growth and WUE at leaf and yield levels. Salinity stress significantly decreased photosynthetic rate, stomatal conductance, intercellular CO₂ concentration and transpiration rate by 20.7, 26.3, 10.5 and 27.2%, respectively. Lower biomass production and grain yield were probably due to the restrained photosynthesis under drought and salinity stress. Biochar addition significantly enhanced soybean grain yield by 3.1–14.8%. Drought stress and biochar addition significantly increased WUE_-yield by 27.5 and 15.6%, respectively, while salinity stress significantly decreased WUE_-yield by 24.2%. Drought and salinity stress showed some negative interactions on soybean productivity and leaf gaseous exchange. But biochar addition alleviate the negative effects on soybean productivity and water use efficiency under drought and salinity stress. Conclusions: The results of the present study indicated that drought and salinity stress could significantly depress soybean growth and productivity. There exist interactive effects of drought and salinity stress on soybean productivity and water use efficiency, while we could employ biochar to alleviate the negative effects. We should consider the interactive effects of different abiotic restriction factors on crop growth thus for sustainable agriculture in the future.

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.

Acidic tea soil is an important greenhouse gas (GHG) emission source.Few studies have been done to investigate the impact of alkaline biochar addition on acidicsoil GHG emissions. We carried out a 40-day aerobic incubation experiment to investigate the alkaline biochar amendment on carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions from an acidic tea soil under N application. Soil samples were collected in the 0-15 cm layers from a tea orchard of Purple Mountain in Nanjing, Jiangsu Province, China. The results showed that biochar amendment significantly increased soil pH, dissolved organic carbon (DOC), total dissolved nitrogen (TDN), and the ratio of DOC/TDN at the end of incubation. N fertilization increased all three GHG emissions. In contrast, biochar amendment significantly decreased soil CO2 and N2O emissions by 7.2-9.3% and 36.3-44.2%, respectively. Although the interaction of biochar and N fertilizer on soil CO2 and CH4 emissions were not obvious, N2O emissions were significantly affected by their interaction. Consistent with CO2 and N2O emissions, the net GWP was significantly decreased by biochar addition. Overall, the present study suggests that biochar amendment could be used as an effective management mitigating soil GHG emissions and the net GWP from the acidic tea field soil.

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.