CFD and field trials pinpoint optimal biogas slurry mixing and irrigation for Chinese yam

Biogas slurry, the nutrient-rich liquid left over from anaerobic digestion, can serve as a valuable fertilizer, but applying it effectively requires careful control of how it is blended with water and delivered to crops. A new study published in Scientific Reports combined computational fluid dynamics simulation with field experimentation to tackle both ends of that problem, from pipeline design to irrigation scheduling for Chinese yam. The research team first used numerical simulation to examine three designed mixed fertilizer pipeline structures, testing how the order in which components enter the pipe affects blending efficiency in pipes of identical diameter.

The simulations employed the realizable k-epsilon turbulence model, and the researchers evaluated blending uniformity using the velocity-based coefficient of variation, a statistical measure in which lower values indicate more uniform mixing. The results pointed clearly to one design. The stepwise mixing structure b, which follows an anaerobic liquid–water–trace elements sequence, achieved the best fertilizer mixing uniformity, with a flow velocity of 6.65 meters per second and a relative standard deviation, expressed as the coefficient of variation, of 6.47%.

Building on that optimal structure, the team assembled an integrated biogas slurry irrigation machine characterized by high integration and intelligent control. The apparatus incorporated solenoid valves, centrifugal pumps, and smart controllers, linking the computationally optimized pipeline design to a practical delivery system capable of regulated, automated operation in the field. With the hardware in place, the researchers turned to agronomic optimization through a two-factor field experiment.

Two-factor analysis of variance revealed statistically significant effects of slurry concentration, irrigation lower limit, and the interaction between the two factors on the crop performance indicators measured in the trial. Five key indicators were assessed comprehensively: soil moisture content, yam yield, soluble protein content, starch content, and economic returns. The combined analysis identified one treatment as the clear leader.

Irrigation at 75% slurry concentration combined with a 75% field capacity lower limit, designated F3T2, produced superior Chinese yam production and starch content compared with the other tested combinations. The entropy weight method confirmed this result, giving F3T2 the highest comprehensive evaluation value of 0.97 among the treatments examined. The study's significance lies in the coherent framework it establishes, connecting engineering optimization at the level of fluid dynamics and machinery design to precision agronomy at the level of irrigation and fertilization management.

Rather than treating slurry application as a single undifferentiated practice, the approach decomposes it into mixing uniformity, delivery hardware, and irrigation scheduling, each addressed with quantitative methods. The authors position the work as a replicable strategy for transforming agricultural waste into a resource with enhanced efficiency and economic return. Because the pipeline design principles, machine configuration, and experimental framework are documented, the approach could in principle be adapted to other crops and biogas slurry application contexts, though the field results reported here apply specifically to Chinese yam under the tested concentration and moisture conditions.

This study contributes a concrete, validated pathway: a stepwise mixing sequence verified by simulation, an integrated intelligent irrigation machine built around it, and an empirically determined irrigation recipe that delivered the best measured combination of yield, quality, soil moisture, and economic performance in the trial.

Subject of Research: Optimizing biogas slurry mixing and irrigation for Chinese yam using computational fluid dynamics and field experiments

Article Title: Integrating computational fluid dynamics and field experiments to optimize mixing and irrigation strategies for biogas slurry application in Chinese yam

Article References: Lu, J., Gao, Y., Tian, Y., Shao, Y., Li, J., Li, J., Du, L., Chen, Q., Chen, J., Zhang, H., & Zhong, F. (2026). Integrating computational fluid dynamics and field experiments to optimize mixing and irrigation strategies for biogas slurry application in Chinese yam. Scientific Reports. https://doi.org/10.1038/s41598-026-72063-3

Image Credits: AI Generated

DOI: 10.1038/s41598-026-72063-3

Keywords: biogas slurry, computational fluid dynamics, irrigation, Chinese yam, mixing uniformity, entropy weight method, precision agriculture, anaerobic digestion, soil moisture, crop yield, Integrating, computational