Synergistic Biochar–Wood Vinegar Amendments Boost Soil Microbial Function, Carbon Sequestration, and Crop Productivity Across European Agroecosystems

Purpose This study examines whether biochar, applied alone or in combination with wood vinegar (pyroligneous acid), can simultaneously enhance soil biological functioning, carbon sequestration, and crop productivity across contrasting European agroecosystems. The central research question was whether the combined amendment (Biochar SL) provides synergistic benefits over single‐input applications. Methods Multiyear field experiments (2022–2024) were conducted in Romania (RO), Hungary (HU), Germany (DE), and Bulgaria (BG) using winter wheat. Three treatments were compared: biochar (Biochar S), biochar enriched with wood vinegar (Biochar SL), and wood vinegar alone (Wood Vinegar L), against conventional management. Soil enzyme activity, soil organic carbon (SOC), microbial biomass, grain yield, and UAV‐derived normalized difference vegetation index (NDVI) were measured. Spatial crop performance was evaluated using Moran’s I spatial autocorrelation, and yield data were obtained from both GPS‐linked harvesters and replicated plot measurements. Results Biochar SL consistently produced the strongest responses. Across 48 harvests, mean grain yield increased by 5.6% relative to controls, with site‐specific gains up to 17.7% (≈515 kg ha −1 ). Soil enzyme activity rose by approximately 3.3%, indicating enhanced microbial functioning. SOC increased markedly in low‐fertility soils, nearly doubling in RO (4.13% to 9.62%). NDVI values improved by approximately 0.3 units, and strong spatial clustering of high‐vigor zones (Moran’s I = 0.78, p < 0.01) reflected more uniform crop development. Conclusions The combined biochar–wood vinegar amendment synergistically enhances soil biological activity, carbon storage, and crop performance across diverse European conditions, offering a scalable strategy for climate‐resilient and sustainable agroecosystem management.