Application of biostimulants in benzo( a)pyrene polluted soils: Short-time effects on soil biochemical properties

Abstract

The bioremediation effects of three biostimulants (BS): WCDS, wheat condensed distillers soluble; PAHE, hydrolyzed poultry feathers; and RB, rice bran extract in a soil polluted with two rates of benzo( a)pyrene (BaP) (50 or 100 mg kg −1 soil, respectively) over 90 days were studied. Their effects on the soil biochemical properties (ATP and urease and phosphatase activities) and ergosterol were determined. Also, extractable BaP in soils was determined during the incubation period. An non-polluted and non-organic-amended soil was used as control. The results indicated that at the end of the incubation period and compared with the control soil, the ATP, ergosterol, urease and phosphatase activities decreased 29.4%, 24.8%, 44.7% and 42.9%, respectively in the non-organic amended soil polluted with polluted 100 mg BaP kg −1 soil. The application of biostimulants to unpolluted soil increased the biochemical parameters. However, this stimulation was higher in the soil amended with PAHE, followed by RB and WCDS. The application of BaP in organic-amended soils decreased the biochemical properties. However, this decrease was lower than for the non-amended BaP polluted soil. Possibly the low molecular weight protein content easily assimilated by soil microorganisms is responsible for less inhibition of these soil biochemical parameters.