Atrazine degradation in soils: the role of microbial communities, atrazine application history, and soil carbon

Abstract

The degradation rate of atrazine in floodplain soils under natural grasslands and cropped fields in the Liverpool Plains, NSW, was studied under laboratory incubation and in glasshouse bioassays, and related to soil properties including microbial community analysis by t-RFLP. The experiments were part of a broader study aiming to manage pesticides in the environment using vegetative filters (biofilters). The soils differed in their atrazine treatment history. Degradation rate (half-life) in cropped soil was more rapid (≈2 to 7 days) than in 2 grassland soils (≈8 to ≈22 days). Bioassays in the glasshouse using oats and soybeans supported this finding. The t-RFLP analysis disclosed the presence of 2 consortia of bacterial species that are reported in the literature to degrade atrazine. These were: (i) Rhodococcus sp, Pseudomonas aeruginosa, and Clavibacter michiganense and (ii) Acinetobacter sp., Pseudomonas sp., and Streptomyces sp. Their dynamics during incubation suggested that they might have been responsible for the more rapid atrazine degradation in the cropped soil. The enhanced atrazine degradation in cropped soil was also associated with lower concentrations of soil organic C and percentage of light fraction carbon compared with grassland soils, suggesting that atrazine provided an additional source of N and C to organisms that can quickly degrade the herbicide. The finding of relatively short atrazine half-life has implications for the effectiveness of the herbicide, as well as for the loads of pesticide potentially entering the environment. The results suggest there is little risk of atrazine accumulating in biofilters and causing damage.

The effect of natural zeolites and organic fertilisers on the characteristics of degraded soils and yield of crops grown in Western Serbia

“…At the same time, world population growth has brought about both food consumption increase and soil area decrease (Ovuka, 2000;Ramankutty et al, 2002;Lepers et al, 2005). Soil structure deterioration, soil disturbance, frequent accumulation of heavy metals and other hazardous substances, destruction of beneficial soil macro-and microorganisms and alteration of soil chemical properties are induced partly by the effect of nature, abundant precipitations, acid rains and erosion (Kirkby et al, 2000;Lal, 2001;Evans, 2002;Andry et al, 2007) but mostly by human activities (the uncontrolled use of mineral fertilisers and pesticides (Chen et al, 1999;Di et al, 2001;Popov et al, 2005;Hartemink, 2006)). Not only do such soils have reduced fertility, but they also carry risks of producing food of unsuitable quality and questionable safety.…”

Imidazolinone Degradation in Soil in Response to Application History

“…Accelerated degradation of herbicides is the adaptation of a soil microbial population to a chemical compound, which may be used as a carbon source of energy and/or nutrients (Popov et al, 2005;Arbeli & Fuentes, 2007). Repeated application of the same herbicide or a structurally similar molecule is the main factor on adapting microorganisms to degrade a given compound.…”

Atrazine biodegradation efficiency, metabolite detection, and trzD gene expression by enrichment bacterial cultures from agricultural soil

“…(Wang and Xie, 2012), Chelatobacter heintzii (Rousseaux et al, 2001), Rhodococcus sp., Acinetobacter sp., Streptomyces sp., Pseudomonas aeruginosa, Clavibacter michiganense (Popov et al, 2005), Enterobacter cloacae (Shapir et al, 2006), Bacillus megaterium, Alcaligenes faecalis, Klebsiella ornithinolytica, and Agrobacterium tumefaciens (Siripattanakul et al, 2009). Under aerobic conditions, Rhodococcus strain TE1 can metabolize the atrazine into deethylatrazine (DEA) and deisopropylatrazine (DIA) (Behki et al, 1993).…”