Impact of agro-technical measures on the strontium uptake of agricultural crops

Contamination of food with radio-nuclides after nuclear disasters is one of the major threats to human health. The Cernobyl accident in 1986 was an ev ent which affected regions all over the world, it highlighted uncertainty a bout appropriate measures to be employed in order to reduce the entry of ra dio-nuclides into the food chain. Generally oilseed rape showed three to six times higher Sr contents of the vegetative and generative plant parts than cereals. In pot, lysimeter and f ield trials the following measures were tested: liming (Ca supply versus pu re increase of pH value), sulphate and phosphate fertilisation; mixing dept h of Sr (surface contamination (0-1 cm) versus mixing of Sr in the plough l ayer (0-30cm)). In all experiments the seed and grain Sr concentrations, re spectively remained more or less unaffected by the different treatments. Sr transfer into vegetative plant parts of fodder plants was distinctly reduc ed by liming or gypsum fertilisation whereby this influence seems to be wid ely independent of the soil type. A differentiation of liming into a Ca and pH effect showed that an increase in pH had little effect on the Sr uptake while the Ca supply resulted in a significant decrease in the Sr uptake due to Ca/Sr antagonism. The applica tion of extremely high amounts of phosphorus to a soil low in plant availab le phosphorus decreased the Sr contents of oilseed rape and cereals efficie ntly in a pot experiment, but hardly any influence of common P applications on the Sr uptake can be expected. Only extraordinarily high amounts of sul phate were able to reduce the Sr uptake,too. The mixing of Sr within the whole ploughed layer (0-30 cm) decreased Sr con tents of Dactylis glomerata L. by up to 29 % in comparison with Sr added to the soil surface (0-1 cm). Therefore deep and homogenizing soil tillage op erations are a further important measure for the reduction of Sr uptake of plants.