Environmental considerations for interactions between agricultural herbicides and nitrogen fertilizers in water
Agricultural herbicides and fertilizers are widely used and necessary for the production of food and feed. Each herbicide and fertilizer must be extensively researched prior to being released for commercial use. However, some research indicates that an interaction may occur when fertilizers and herbicides are present in soil or water, simultaneously, and growers currently give little attention to the length of time between fertilizer and herbicide applications in the same field. One potential result of an interaction, if it exists, is a decrease in the effectiveness of either of these inputs. Another potential result is the formation of nitrosamines. Nitrosamines, which can be carcinogenic, mutagenic, and teratogenic, are a product of xenobiotic reactions and pose an equal or greater risk to the environment and human health than the parent compounds. The combination of nitrosatable herbicides and high levels of nitrogen in soils used for production agriculture may be a precursor for nitrosamine formation. This study investigates this potential interaction by combining an aqueous nitrate or nitrite solution with individual agricultural herbicides (atrazine, alachlor, dicamba, glufosinate, glyphosate, metolachlor, and trifluralin). The pH of samples was adjusted to investigate the effect of acidic conditions since the nitrosating agent is formed at an acidic pH. The results were then analyzed to detect if the concentration of herbicide and nitrate or nitrite was altered. A preliminary experiment showed that the addition of acetone caused a significant reduction in nitrate concentration, from 25 mg/L to 12.5 mg/L. Additionally, the samples that contained a highly acidic solution showed a significant decrease in nitrite level, from 25 mg/L to 12.4 mg/L. These results indicate that some form of interaction is occurring. A chromatogram from analysis using liquid chromatography-mass spectrometry of a sample containing nitrite and atrazine at pH 2 showed a secondary compound was formed. Samples with a more neutral pH did not show any change in nitrate or nitrite concentration. The results from this research may be pertinent to management decisions for growers, as well as the reduction of contaminants in the environment.
N-nitrosamine, nitrate, nitrite, herbicide, pesticide, acidic, environmental contaminants
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign