Supplementary file 1_Coupling relationships between yield traits of Ipomoea aquatica Forssk. and biogas slurry purification under varied nutrient supplementation regimes.docx

Factorial nutrient supplementation experiments showed that full supplementation with macro-, secondary, and micronutrients (Treatment T4) maximized plant growth, chlorophyll content, and quality indices. The system achieved >90% COD removal across all treatments, while TP removal efficiency was highly dependent on the interaction between AN load and micronutrient supply, which was antagonistic under low AN but synergistic under high AN.

Economic assessment revealed an annual net income of approximately CNY 45133 per mu. The EC model is applicable for initial slurry assessment but not suitable for real-time monitoring after exogenous nutrient addition. This study provides a practical, low-cost integrated strategy for biogas slurry resource utilization and vegetable production, and offers an effective hydroponic I. aquatica system for small- and medium-scale pig farms.</p>