Lab-to-Land: A Field Case Study on Water Hyacinth Biochar as a Low-Cost Soil Amendment for Smallholder Farmers in the Panchganga Basin, Kolhapur

Water hyacinth (Eichhornia crassipes), an invasive aquatic weed, poses environmental challenges in the Panchganga Basin of Kolhapur, Maharashtra, while smallholder farmers face rising agricultural input costs. This study investigates the potential of converting harvested water hyacinth into biochar as a low-cost soil amendment, evaluating its effects on crop growth and estimated input costs under practical farming conditions. A nine-week field pilot involved four smallholder farmers cultivating sugarcane, soybean, and turmeric. Each farm contained a 40 m² treatment plot receiving water hyacinth-derived biochar and an adjacent control plot managed using the farmer’s usual practices. Biochar was produced through low-temperature pyrolysis and incorporated into the soil at planting. Plant height, qualitative soil moisture and pest observations, and estimated input costs were monitored throughout the trial. By week nine, treatment plots recorded an average plant height increase of 34% relative to baseline, compared with 24% in control plots. A growth advantage was observed on three of the four farms, while the turmeric trial showed minimal differences. Estimated input costs were 47–64% lower for biochar treatment than for existing soil amendments. Farmers also reported longer moisture retention in most treatment plots, although pest observations remained qualitative. These preliminary findings suggest that water hyacinth biochar may support sustainable agriculture by linking invasive weed management with potentially lower-cost soil improvement. However, the small sample size, short trial duration, inconsistent monitoring, and absence of laboratory-based soil nutrient analysis limit the conclusions. Larger, multi-season field trials incorporating laboratory soil testing are needed to establish its effectiveness and broader applicability.