Organic amendments to enhance herbicide biodegradation in contaminated soils

Abstract

Pesticide contamination of soil and groundwater at agricultural chemical distribution sites is a widespread problem in the USA. Alternatives to land-farming or solid waste disposal include biostimulation and phytoremediation. This research investigated the ability of compost, corn stalks, corn fermentation byproduct, peat, manure, and sawdust at rates of 0.5% and 5% (w/w) to stimulate biodegradation of atrazine [6-chloro-Nethyl-N′-(1-methyethyl)-1,3,5-triazine-2,4-diamine], metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide], and trifluralin [2,benzenamine] added as a mixture to soil. Initial concentrations were 175±42 mg atrazine kg-1 soil, 182±25 mg metolachlor kg-1 soil, and 165±23 mg trifluralin kg-1soil. After amendment addition, 30% of the atrazine, 33% of the metolachlor, and 44% of the trifluralin was degraded over 245 days, which included 63 days' aging prior to amendment additions. Atrazine degradation was enhanced by 0.5% manure, 5% peat, and 5% cornstalk amendments compared to nonamended soils. Metolachlor degradation was enhanced by all amendments at the 5% level, except for compost and peat. Amendments had no effect on trifluralin degradation. The 5% addition of compost, manure, and cornstalks resulted in significant increases in bacterial populations and dehydrogenase activity. A second experiment compared the persistence of atrazine, metolachlor, and trifluralin applied in a mixture to their persistence in soil individually. A combined average of 123 mg atrazine kg-1 remained in soil treated with the three-herbicide mixture compared to 31 mg atrazine kg-1 remaining in soil treated with atrazine only. Atrazine mineralization and atrazine-degrading microorganisms were suppressed by high concentrations of metolachlor, but not by trifluralin. Abstract Pesticide contamination of soil and groundwater at agricultural chemical distribution sites is a widespread problem in the USA. Alternatives to land-farming or solid waste disposal include biostimulation and phytoremediation. This research investigated the ability of compost, corn stalks, corn fermentation byproduct, peat, manure, and sawdust at rates of 0.5% and 5% (w/w) to stimulate biodegradation of atrazine [6-chloro-N-ethyl, and trifluralin [2,6-dinitro-N, N-dipropyl-4-(trifluoromethyl)benzenamine] added as a mixture to soil. Initial concentrations were 175±42 mg atrazine kg -1 soil, 182±25 mg metolachlor kg -1 soil, and 165±23 mg trifluralin kg -1 soil. After amendment addition, 30% of the atrazine, 33% of the metolachlor, and 44% of the trifluralin was degraded over 245 days, which included 63 days' aging prior to amendment additions. Atrazine degradation was enhanced by 0.5% manure, 5% peat, and 5% cornstalk amendments compared to nonamended soils. Metolachlor degradation was enhanced by all amendments at the 5% level, except for compost and peat. Amendments had no effect on trifluralin degradation. The 5% addition of compost, manure, and cornstalks resulted in significant increases in bacterial popula...

Biostimulation for the Enhanced Degradation of Herbicides in Soil

“…Acknowledged the use of organic amendments as an inexpensive option for the disposal of herbicide waste [46] Cellulose, straw, and compost Atrazine Organic matter addition stimulated the herbicide dealkylation in nonadapted soils [47] Compost, corn stalks, corn fermentation by-product, peat, manure, and sawdust Atrazine, trifluralin, and metolachlor 5% addition of amendments resulted in significant increase in bacterial population and dehydrogenase activity [48] Raw olive cake Chlorsulfuron, prosulfuron, and bensulfuron Stimulated the microbial dehydrogenase activity [49] Biogas slurry, mushroom spent compost, and farm yard manure Atrazine Atrazine dissipation was observed to be highest (34%) with biogas slurry [4] Rice straw, farm yard manure, saw dust, and charcoal Atrazine…”

Persistence of 14C-labeled atrazine and its residues in a field lysimeter soil after 22years

“…Most findings regarding fungal or microbial (Kaufmann and Blake, 1970;Mandelbaum et al, 1993;Assaf and Turco, 1994a) and chemical (Blumhorst and Weber, 1994) degradation are based on laboratory or short-term field experiments which have limited relevance to long-term outdoor trials. The estimated half-life of atrazine from these short-term tests ranges between a few days to about one year (Kruger et al, 1993;Accinelli et al, 2001), depending on application history (Shaner and Henry, 2007), soil depth (Miller at al., 1997), soil moisture content (Kruger et al, 1993), temperature (Dinelli et al, 2000), pH and presence of other nutrients such as nitrogen or carbon (Abdelhafid et al, 2000;Assaf and Turco, 1994b;Gan et al, 1996;Moorman et al, 2001;Alvey and Crowley, 1995). The environmental behavior of atrazine by addition of organic amendments, like plant residues, or its mineralization during bioremediation, field application and agricultural use has been studied intensively (Alvey and Crowley, 1995;Barriuso and Houot, 1996;Silva et al, 2004).…”

Persistência do herbicida S-metolachlor associado ao glyphosate ou paraquat em plantio direto

“…O herbicida atrazine retardou a degradação do herbicida cyanazine em extratos celulares (Gebendinger & Radosevich, 1999). A mineralização e a degradação do atrazine (175 mg kg -1 solo) por microrganismos foram atrasadas por altas concentrações de metolachlor (182 mg kg -1 solo), mas não por trifluralin (165 mg kg -1 solo) (Moorman et al, 2001). Entretanto, os herbicidas atrazine e pendimethalin, na concentração de 50 mg kg -1 de solo, não tiveram efeitos na degradação do metolachlor (Anhalt et al, 2000).…”