Abstract We tested the effects of wastewater from olive processing, applied alone or in combination with different mineral complements, in pots containing calcareous soil. An initial barley crop, and a subsequent ryegrass crop, yielded information on the direct and delayed effects, respectively, of the by‐product on Zn and Cu assimilability in the soil‐plant system. As a direct effect, the application of wastewater tended to decrease Zn assimilability, but the delayed effect showed the opposite trend, especially when the by‐product was added together with N‐containing mineral supplements. The direct effect generally did not significantly modify Cu assimilability, however, the delayed effect significantly enhanced Cu uptake; this effect was potentiated by the joint application of N and P. At the end of the experiment, a residual effect of the application of wastewater alone was observed, as a significant increase in extractable Cu in soil, and a nonsignificant rise in extractable Zn.
[1]
A. McIntosh.
Copper in the Environment
,
1983
.
[2]
D. Vaughan,et al.
Soil Organic Matter and Biological Activity
,
1985,
Developments in Plant and Soil Sciences.
[3]
Shahamat U. Khan,et al.
Humic substances in the environment
,
1972
.
[4]
A. E. Greenberg,et al.
Standard methods for the examination of water and wastewater : supplement to the sixteenth edition
,
1988
.
[5]
M. Kononova.
Soil Organic Matter
,
1963
.
[6]
B. Ulrich,et al.
Effects of the Accumulation of Air Pollutants in Forest Ecosystems.
,
1983
.