Abstract: | Abstract Two contrasting soils were extracted with 0.05 M EDTA in 1 M CH3 COONH4 at pH 6, before and after incubation for 4 weeks at constant (10, 20 or 30°C) or fluctuating (10/30, mean 20°C) temperatures. Less copper was extracted from soils which were incubated at fluctuating temperature than from those maintained at a constant 20 C. Where incubation temperature was constant, extractable copper increased or decreased with increasing temperature depending on the soil and how it was treated. Recovery of added copper was low initially but increased during the incubation. Maximum recovery was associated with low incubation temperature in one soil, but high temperature in the other. The amounts of copper extracted were slightly increased by γ‐irradiation of the soils. Extractable copper was also increased by increasing the temperature at which the extraction was performed. |