Glyphosate: environmental fate and impact

Glyphosate is the most used herbicide worldwide, which has contributed to concerns about its environmental impact. Compared with most other herbicides, glyphosate has a half-life in soil and water that is relatively short (averaging about 30 d in temperate climates), mostly due to microbial degradation. Its primary microbial product, aminomethylphosphonic acid, is slightly more persistent than glyphosate. In soil, glyphosate is virtually biologically inactive due to its strong binding to soil components. Glyphosate does not bioaccumulate in organisms, largely due to its high water solubility. Glyphosate-resistant crops have greatly facilitated reduced-tillage agriculture, thereby reducing soil loss, soil compaction, carbon dioxide emissions, and fossil fuel use. Agricultural economists have projected that loss of glyphosate would result in increased cropping area, some gained by deforestation, and an increase in environmental impact quotient of weed management. Some drift doses of glyphosate to non-target plants can cause increased plant growth (hormesis) and/or increased susceptibility to plant pathogens, although these non-target effects are not well documented. The preponderance of evidence confirms that glyphosate does not harm plants by interfering with mineral nutrition and that it has no agriculturally significant effects on soil microbiota. Glyphosate has a lower environmental impact quotient than most synthetic herbicide alternatives.

EVALUATION OF THE IMPACT OF DYKE ON THE PRACTICE OF USING PLANT PROTECTION CHEMICALS AND THE ENVIRONMENT IMPACT QUOTATION INDEX OF RICE CULTIVATION AREAS IN THAP MUOI, DONG THAP PROVINCE

This report presents the result of a survey to evaluate the use of crop protection chemicals (pesticides – HCBVTV) in rice-growing areas with dyke, semi-dyke and no embankment based on interview result with 112 interviewers such as farmers, agricultural specialists, and pesticide dealers in Thap Muoi District, Dong Thap Province and pesticide usage data recorded by three selected framers in 3 different dyke systems. It showed that dyke practice affects the use of pesticides of farmers. After dykes constructed, the pesticides used were more diverse, with higher dosage compared to before having embankments. The report also evaluates the risk of using pesticides through Environmental Impact Quotient (EIQ) index. It showed that areas with dyke and semi-dyke have much higher EIQ index than areas without embankment, 167, 145 and 54, respectively.

Genetically engineered crops and pesticide use in U.S. maize and soybeans

The widespread adoption of genetically engineered (GE) crops has clearly led to changes in pesticide use, but the nature and extent of these impacts remain open questions. We study this issue with a unique, large, and representative sample of plot-level choices made by U.S. maize and soybean farmers from 1998 to 2011. On average, adopters of GE glyphosate-tolerant (GT) soybeans used 28% (0.30 kg/ha) more herbicide than nonadopters, adopters of GT maize used 1.2% (0.03 kg/ha) less herbicide than nonadopters, and adopters of GE insect-resistant (IR) maize used 11.2% (0.013 kg/ha) less insecticide than nonadopters. When pesticides are weighted by the environmental impact quotient, however, we find that (relative to nonadopters) GE adopters used about the same amount of soybean herbicides, 9.8% less of maize herbicides, and 10.4% less of maize insecticides. In addition, the results indicate that the difference in pesticide use between GE and non-GE adopters has changed significantly over time. For both soybean and maize, GT adopters used increasingly more herbicides relative to nonadopters, whereas adopters of IR maize used increasingly less insecticides. The estimated pattern of change in herbicide use over time is consistent with the emergence of glyphosate weed resistance.

Application of environmental impact quotient model to Kumluca region, Turkey to determine environmental impacts of pesticides

Besides the new developments in agricultural technology, intensive use of pesticides poses a great environmental hazard. The unthinking use of pesticides leads to contamination of air, water and soil. There are several pesticide risk indicator models available in the literature to assess pesticide impacts on the applicator and the ecosystem which is an important issue. This paper refers to an application of a pesticide risk indicator model, called Environmental Impact Quotient (EIQ) which was developed to measure the environmental impacts of pesticide active ingredients used in vegetable and fruit production. The application site is the Kumluca region of Turkey, which is well known for its intensive agricultural activities. As the first step in the model application, EIQ values have been calculated for 35 commonly used pesticides in Kumluca. EIQ values were then turned into EIQ field use rating results based on the active ingredient percent and application rate. Furthermore, some pesticide management scenarios were evaluated to select the least detrimental pesticide by comparing EIQ model results. The EIQ model is an easily applied and very helpful tool for pest management practitioners and agricultural specialists. It can be used efficiently to compare different agricultural pest management strategies or programs.