Biochar addition (BA) has been considered a promising strategy for mitigating soil greenhouse gas (GHG) emissions. However, it is essential to assess whether the benefits are retained under different water and fertilizer strategies (WFSs), particularly under the biogas slurry strategy (BSS), and the specific effects of different BA ratios on GHG emissions must also be assessed. This study examined the effects of two WFSs on soil GHGs emissions and bacterial sub-communities under different BA ratios and investigated their potential mechanisms using soil column experiments. Under the conventional chemical fertilizer strategy (CFS), BA reduced CO₂ emissions by 29.19–36.51%, but simultaneously increased CH₄ emissions by 21.62–135.08% and N₂O emissions by 48.16–51.31%. Transitioning from CFS to BSS led to a 14.89% reduction in CO₂ emissions and a 71.83% reduction in N₂O emissions, whereas the CH₄ emissions increased by 101.72%. Concurrently, BA concentrations of 4% and 6% intensified the modulatory effect of BSS on these GHGs, whereas a 2% BA concentration had an opposing regulatory effect. Both BSS and BA were also found to enhance the abundance of rare bacterial sub-communities within the soil. Furthermore, this study revealed that BSS reshaped the GHG emission pathway regulated by BA through bacterial sub-communities, emphasizing the ''priority effect'' of these communities in controlling GHG emissions. This study has also highlighted the integral role of carbon and nitrogen turnover processes within bacterial sub-communities for the regulation of GHGs emissions. In conclusion, this study demonstrates that the effectiveness of BA in reducing soil GHGs emissions depends on the WFS. Graphical Abstract

Heavy launch vehicles use liquid oxygen (LOX) and kerosene propellants for their high specific impulse and controlling precision. However, incomplete burnt exhaust gas reacts easily with air, which...

Under drip irrigation conditions, the transport pattern of soil water in the root zone directly affects the water use efficiency of crops. The type of soil matrix, initial moisture content, and irrigation water quality jointly determine the hydrodynamic process of water infiltration. However, as a special type of irrigation water, the water movement mechanism of biogas slurry under drip irrigation in soilless cultivation substrates still lacks systematic investigation. In this study, transparent soil column infiltration experiments were conducted using two types of cultivation substrates—organic (coconut coir) and inorganic (desert sand)—under controlled facility conditions. Three initial moisture contents (10%, 15%, and 20%) and two irrigation water qualities (tap water and diluted biogas slurry) were combined to form twelve treatment groups. Soil moisture sensors and visualization techniques were employed to quantitatively analyze the wetting front morphology, vertical and horizontal infiltration rates, wetting ratio, and soil moisture profile distribution under different treatments. The results showed that the initial moisture content significantly influenced the advancement pattern of the wetting front. Higher initial moisture levels promoted the transformation of the wetting front shape from a “semi-pear” form to a “hemispherical” one and reduced the rate of infiltration decline. The coconut coir substrate exhibited stronger vertical infiltration capacity and a central water aggregation characteristic, whereas the desert sand demonstrated a wider horizontal expansion range. Under low and moderate initial moisture conditions, the application of biogas slurry enhanced horizontal water diffusion and improved the uniformity of the wetted zone, with the wetting ratio increasing by more than 6% compared with high moisture conditions. In addition, the power function model provided an excellent fit for the cumulative infiltration process across all treatments (R² > 0.96), indicating its suitability for describing the water transport process in facility cultivation substrates. This study provides theoretical support for precise water and fertilizer management and the efficient utilization of biogas slurry in soilless cultivation systems.

The Euler-Lagrange model of Jet-gas and AL₂O₃ is established to study the impact of gas-particle jet flow during canister launching process. The gas phase is the Navier-Stokes equation of the two-component transport of gas and air, and the turbulence model is the realizable two-equation model. The airflow flux is numerically discretized via AUSM format, and the viscous dissipation flux is a second-order central difference. The movement trajectories of particles with different diameters ranging from 1 to 100 μm and the distribution characteristics of jet flow dynamic parameters in the launching box are studied. The jet impingement flow field results of gas-particle two-phase flow are compared with those without particle phase. The results show that the particle phase has a retardation and heat transfer effect on the expansion of jet flow, which affects the distribution of jet flow parameters in the launch canister. Furthermore, compared with the pure jet flow impingement effect, the velocity of the two-phase jet flow along the central axis decreases and the temperature increases. Meanwhile, the trajectory of the particle phase is related to the particle diameter. As the diameter of the particles becomes smaller, the flow ability is better and affected by turbulence, and a random movement area in the downstream area of the jet is formed. As the diameter of the particles becomes larger, a particle aggregation area is formed on the jet axis due to inertial force.

Water management is a key factor affecting crop physiology and rhizosphere microbial ecology in protected agriculture. However, the responses of root development and bacterial community structure to different lower irrigation limits and drip irrigation flow rates in coir substrates remain poorly understood. This study investigated greenhouse-grown tomatoes in the Gobi region under three lower irrigation limits (30%, 50%, and 70% of substrate water-holding capacity) and two drip irrigation flow rates (1 and 2 L·h⁻¹). Substrate moisture, root traits, bacterial community structure, co-occurrence networks, and functional potential were evaluated. Increasing the lower irrigation limit maintained higher and more stable substrate moisture and generally enhanced root length, root surface area, root tip number, and root activity. W3Q1 promoted greater spatial expansion of the root system, whereas W2Q2 produced the largest root volume and maintained relatively high root activity. Irrigation combination significantly altered bacterial community structure but had limited effects on bacterial richness. W2Q1 enriched Bacillota-related taxa, whereas W2Q2 enriched Pseudomonadota and exhibited greater bacterial network connectivity and modularity. FAPROTAX-based functional prediction indicated that the bacterial communities were mainly associated with chemoheterotrophy, organic matter decomposition, and nitrogen transformation. Overall, the lower irrigation limit primarily regulated substrate moisture and root traits, whereas the effects of drip irrigation flow rate were trait- and irrigation-limit-dependent, with significant main and interaction effects on root volume. These findings provide a basis for optimizing precision irrigation in coir-substrate tomato cultivation in arid greenhouse systems.