Comparative implications of tobacco and non-tobacco crop farming on aquatic ecosystems: a multi-index evaluation of irrigation suitability and pollution risks.

Agriculture plays a dual role, both contributing to and being impacted by water pollution. This study evaluates the impact of tobacco and non-tobacco farming on irrigation suitability, water quality index (WQI), water health index (WHI), heavy metal (HM) pollution, and ecological risk (ER). Twenty-four water samples from six tobacco fields (TFs) and six non-tobacco fields (NTFs), collected before cropping season and after cropping season, were analyzed for major physico-chemical properties and HMs. The results suggest that TF improves sodium and alkalinity hazards but worsens nutrient and HM pollution (Pb: 0.119 mg/L, Cd: 0.021 mg/L, Ni: 0.242 mg/L), and threatens salinity, permeability, osmotic potential (OPπ), dry residue (RS), and miscellaneous hazards. Conversely, NTF has minimal impact, except for nutrient and miscellaneous hazards. WQI shifts from good to very poor, primarily driven by turbidity, PO-P, K, and NO-N. Similarly, WHI declines from excellent to very poor in TF and from good to poor in NTF. HM pollution index has risen slightly above irrigation safety limits, mainly due to Cd, Ni, and Pb, resulting in a slightly elevated ER. This study demonstrates that TF, driven by excessive agrochemical use, renders water unsuitable for irrigation, underscoring the imperative for sustainable practices.