In the period from 2014 to 2021, in the context of radioactive contamination of the flood meadow of the central floodplain of the Iput river, Novozybkovsky district, Bryansk region, studies were carried out on the role of nutrients in the accumulation of radioactively contaminated flood meadows 137Cs the green mass of herbs and the forecast of 137Cs migration in the "soil-plant-animal-human" system with a radioactive contamination density 137Cs the territory above 555 kBq/m2. As a result of the studies, it was found that without the use of special measures, the flood meadow cannot be used as a pasture, the content of 137Cs in the feed production exceeds the standard by 16 times. Despite the fact that in 2016 the first half-life of the 137Cs occurred, a significant decrease in the accumulation of water meadow 137Cs by vegetation was not revealed. It was found that with an increase in potassium to nitrogen in mineral fertilizer, the accumulation of natural grass 137Cs by the green mass is significantly reduced. The correlation coefficient is 0.53-0.65 between nitrogen fertilization and accumulation 137Cs vegetation of flood meadow. The inverse strong relationship between potash fertilization and accumulation 137Cs vegetation of the flood meadow was revealed, the correlation coefficient is 0.89-0.97. Nitrogen fertilizers increase the productivity of flood meadows, but are a factor in increasing the accumulation of natural grass with 137Cs green mass. Potash fertilizers reliably reduce accumulations 137Cs vegetative mass of natural grass stand and level negative effect of nitrogen fertilizer. The return of radioactively contaminated forage to agricultural circulation is possible only with the use of increased doses of potash fertilizer, which serve as a barrier to migration of 137Cs in the "soil-plant-animal-human" system.