Increasing the metal concentrations by amending the sewage sludge increased the metal
content in barley leaves. The yield of the 100 % sludge was the lowest and the soil pH was
lowered as well. With the increase in time, the metal removal by plants is also increased.
Chromium in barley behaved differently to the other metals studied, showing a declination
with time. High voltage application of soluble chromium in solution culture resulted in
decreased concentration of nitrogen, phosphorous, potassium , copper, iron, magnesium and
zinc in barley and produced toxic effects and reduced growth. The metal uptake by plants
from sludge amended soil was influenced by time of harvesting and stage of growth.
J. Nouri , P. J. Peterson and B. J. Alloway , 2001. Effect of Variation in Harvest Time on the Uptake of Metals by Barley Plants from Soil Amended with Sludge and Compost. Journal of Biological Sciences, 1: 1056-1059.