Farmland irrigation water sampling method

The invention provides a farmland irrigation water sampling method including the procedures of activated carbon purification, activated carbon absorption bag preparation, sampler installation, sampling and target substance elution; activated carbon after purification is put into a small bag and sealed, an activated carbon absorption bag is prepared, the activated carbon absorption bag is mounted on a sampling rod to prepare a sampler, the sampler is placed in farmland or an irrigation water channel for sampling, a target substance in the activated carbon absorption bag taken from sampling is eluted, and a to-be-measured solution is obtained. The sampler produced with activated carbon as an adsorbent, has quite strong adsorption capacity on various heavy metals, has low cost, has the consistent adsorption capacity after being soaked in water for 30 days, and has the function of long-term accumulation adsorption acquisition of the target substance. The sampling method is simple and is convenient to operate, and provides a sampling method for the heavy metal total amount in water in a longer period for pollution monitoring and evaluation works of the farmland irrigation water.