Effect of agricultural countermeasures on the transfer factor of caesium-137 in onion (Allium cepa L.)

A field experiment, with onion cv. Rampur as the test crop, was conducted to study the effect of two levels (3.7 and 7.4 MBq m-2) of 137Cs and three countermeasures (application of farmyard manure at 12.5 t ha-1, application of extra potassium 100% in excess of that recommended for onion, and deep ploughing with a mold board plough). The crop was harvested at maturity and separated into bulb and sheath and analysed for 137Cs activity using a NaI (Tl) gamma ray spectrometer. The level of 137Cs significantly influenced the transfer factor (TF) in bulbs and sheaths. The levels of 137Cs and TF values were inversely related. The countermeasures had significantly influenced the TF of 137Cs from soil to onion: the values ranged from 0.0009 to 0.0025 m2 kg-1. The TF was highest for the control and the three countermeasures had significantly reduced values. Application of FYM was the most effective of the countermeasures. The other two countermeasures were on a par. They greatly reduced the TF also in onion sheaths; all three countermeasures had similar effects, and recorded significantly lower TF values than did the control