Growth and Metal Uptake of Lettuce [lactuca Sativa L] on Soil Amended with Biosolids and Gypsum

ABSTRACT

Although soil amended with biosolids can improve soil properties, heavy metal uptake by vegetable crops grown on biosolids-amended soil is of concern. This study evaluated the effects of biosolids and flue gas desulfurization gypsum (FGDG) on yield and metal uptake of two consecutive crops of lettuce. A soil was amended with limed or composted biosolids at rates of 40 and 80 T ha⁻¹ with and without 10 T ha⁻¹ FGDG or with FGDG alone. At both harvests, lettuce yield was higher, compared with the unamended control, in all biosolids treatments, whereas FGDG alone did not significantly affect yield. Lettuce lead concentration was below instrument detection limits. Copper, manganese and zinc concentrations were highest in plants grown in the composted biosolids treatments for the first crop. Cadmium and copper were highest in the limed biosolids in the second. In all cases metal concentrations, did not exceed the range found in lettuce.

KEYWORDS:

• Biosolids
• gypsum
• lettuce
• heavy metals