Herbicide persistence, rotational safety and terminal residue levels in dominant cropping systems of Punjab, India

Sustainable weed management in intensive cropping systems requires systematic evaluation of herbicide persistence, rotational safety and terminal residue behaviour. Punjab, characterized by high cropping intensity and cereal-dominated rotations, represents one of the most herbicide-intensive agricultural state in India. The present review compiles multi-year field data on soil dissipation (DT50), rotational crop response and harvest residue levels of major herbicides used across rice, wheat, maize, cotton, pulses, oilseeds and vegetable systems in Punjab, India. Dissipation studies indicated molecule-specific behaviour, with most herbicides exhibiting low to moderate persistence under prevailing agro-ecological conditions. Even where relatively extended soil persistence was observed, no consistent rotational injury or progressive soil accumulation occurred when herbicides were applied as per the recommendation. Biphasic dissipation patterns were noted for selected herbicides under contrasting water regimes, particularly in rice-based systems. Terminal residue level studies across crops consistently demonstrated concentrations at or below the analytical limit of quantification, and none exceeded established maximum residue limits. Detectable residues, where observed, remained substantially below national and international regulatory thresholds. Dietary exposure assessments conducted for selected herbicides indicated hazard quotient values well below unity, confirming negligible chronic dietary risk under recommended agronomic use of herbicides. The overall compiled evidence supports the safe and integrated use of herbicides in Punjab's intensive production systems when applied as per the recommendations. Continued residue monitoring and adherence to recommended application practices remain essential to maintain agronomic productivity, consumer safety and market confidence.