(137)Cs uptake by plants from sandy sooddy-podzolic soil under nitrogen fertilization

The crops cultivation on sandy sod-podzolic soils is impossible without application of nitric fertilizers (NF). However in the conditions of soil pollution sup(137)Cs NF provoke the growth of specific accumulation of sup(137)Cs in plant products. Influence of nitrogen (N) and potassium (K) ratio in soil and fertilizer on accumulation sup(137)Cs in plants and also the relationship between availability to plants of soil N and fertilizer N and the content sup(137)Cs in a crop at different doses of K fertilizers were studied. The site of experiments was located in the Novozybkovsky district of the Bryansk region (this territory was exposed to the Chernobyl accident). The oat plants were fertilized with NF labeled with a stable isotope sup(15)N. NF in various doses and also N-K fertilizers with various N:K ratio were applied in a pot experiment and in 2 small-plot field experiments. The plots were differed in the exchangeable K and total N contents. It is established that intake of sup(137)Cs from soil by plants was stimulated with N and limited to K (until the achievement of certain concentration of available K in soil). The suppressing effect of K was expressed more strongly than the stimulating effect of N. Applying NF promoted narrowing the N:K ratio in soil and increasing the accumulation of sup(137)Cs in plants. The application of an N-K fertilizer with N:K ratio 1:2 on soil containing approximately 40 mg/kg of an exchangeable K was optimum. An increase of the exchangeable K content in soil up to 80-120 mg/kg leveled out the negative action of NF. Close positive correlation between additional accumulation by plants of soil N and sup(137)Cs intake under the influence of NF is established. A rise of specific accumulation of sup(137)Cs could be caused by strengthening the mineralization processes in soil, leading to the growth of available N and radionuclides release from easy destructed organic soil components and also activation of the root system absorbing activity.