THE EFFECT OF APPLICATION OF POTASSIUM HUMATE ON THE CONTENT OF CADMIUM, ZINC AND ARSENIC IN PLANTS

To study the effect of potassium humate (Tab. I) on the yield of culti vated crops and accumulation of cadmium (Cd), zinc (Zn) and arsenic (A s) in plant biomass, pot trial was established with silage maize, hayl age oat, poppy and spring barley. Three different contaminated soils f rom the locations Cerveny Ujezd, Prestanov and Kbely (Tab. II) were us ed in the trial. Potassium humate was applied by spray during the grow ing season of cultivated crops at a dose of 20 mg in 20 mi solution pe r pot. Agrotechnical data of the trial are summarized in Tab. III. The yield of cultivated crops was not affected statistically significantl y by application of humate. It was ranged between 92 and 114% of the y ield of control treatments (Tab. IV). It was evident from investigatio n of accumulation of Cd in biomass of cultivated crops that with its i ncrease of concentration in soil increased also its content in tissues of plants. Spraying of humate resulted in the decrease of the Cd cont ent in all crops, except poppy where in turn a significant growth of c oncentration of this element was observed (in seed by Is to 29% and ca psule by 32 to 53%) (Fig. 1). Merely in acid soil the content of Cd de creased in this crop. Similarly to the case of Cd, humate application had an effect on the decrease of Zn concentration in barley grain and straw and in haylage oat (Pig. 2). In maize and poppy Zn content incre ased. The most marked increase by 171% was determined in capsule in so il of Kbely. As content in biomass of crops was investigated in the fi rst and last year of experiment. In both cultivated crops (maize and b arley) after humate application its concentration in biomass (Pig. 3) increased. Results of the experiment confirmed the positive effect of humate on the decrease of Cd and Zn content in cereals and its differe nt effect on uptake of these elements by poppy. The increase of As con centration in tissues of investigated crops was found as well.