Biodegradation of atrazine in soil using poultry litter

Abstract

Microorganisms, including Pseudomonas and Actinomycetes species, are known to degrade atrazine and other pesticides in soil. Poultry litter has a large number of microorganisms along with many nutrients. Atrazine is applied to soil at times soon after using poultry litter as manure. The objective of this research was to study the degradation of atrazine (2 or 3 ppm) in soil using poultry litter. The soil + atrazine mixture was treated with either poultry litter, gamma irradiated poultry litter or water extract of the irradiated litter in order to differentiate between the effects of microorganisms, nutrients and organic matter. Atrazine in the soil was extracted with water and methanol and analyzed by pesticide immunoassay (ELISA) 1, 5, 10, 30 or 60 d after poultry litter treatment. The small loss of atrazine from soil treated with the irradiated litter was almost the same as from the sterile soil with no poultry litter. Atrazine was significantly (86%) degraded in soil with untreated poultry litter within 30 d. Degradation was virtually completed within 60 d. The rate of atrazine biodegradation with poultry litter was almost 2 times faster than without the litter. The toxicity (EC 50) of the samples after treatments, to Photobacterium phosphoreum (“Microtox”), was also measured. The toxicity of the soil + atrazine mixture treated with poultry litter (both the untreated and the gamma irradiated) was the same as that of the soil + litter mixture; no significant concentrations of toxic by-products were produced from the biodegradation of atrazine.