TOXIC EFFECTS OF HEAVY METALS ON CROP PLANTS GROWN IN SOIL CULTURE

A number of pot experiments were made on various crops, to study the effects on the chemical composition of the plants of treating the soil with cobalt, copper or nickel sulphates, or with the cupric or ferric salts of ethylenediamine-tetraacetic acid (EDTA).
The tops of copper sulphate-treated plants usually contained higher concentrations of copper, manganese, calcium and magnesium and lower concentrations of potassium and phosphorus, than those of control plants.
The most marked effect of cobalt on oat was to increase the concentration of Ca+Mg in the tops; nickel had a profound effect on the composition of barley tops.
Total iron concentration was reduced in oat by cobalt and copper, and in barley by copper and nickel application. Symptoms of iron deficiency appeared only in the oat plants, their incidence being correlated with the reduction in iron concentration in the tops.
The ferric salt of EDTA tended to reduce the incidence of iron deficiency symptoms produced in oat by copper sulphate, but also gave rise to distinct toxic effects. Plants given the cupric salt of EDTA contained unusually large amounts of iron.