Water contamination & soy

In the United States, the Environmental Protection Agency has acknowledged that agriculture is the major source of surface water quality problems in 72% of impaired rivers, 56% of lakes, and 43% of estuaries.

In the rest of the world, agriculture is also associated with reductions in water quality and availability. Soybean farming plays a significant role in contaminating our waters.
 / ©: Juan Pratginestos / WWF-Canon
Embarkment station for soybeans, Paraguay river, Pantanal.
© Juan Pratginestos / WWF-Canon

Culprits – fertilizers and pesticides

In the United States glyphosate (trade name Roundup) is the main herbicide used in genetically modified soybean production. Glyphosate’s manufacturers have touted it as benign, and can back up their claims with research they have supported. However, further studies suggest otherwise.

Impacts of glyphosate

These other studies allege that glyphosate is linked to reproductive disorders, genetic damage, liver tumours, disrupted embryo development and development delays in mammals (e.g., Cox 1998).

Some producers claim that, with herbicide-tolerant soybeans, one application of herbicide is all that is needed for an entire growing season. But studies show that both the total amount of herbicide used and the number of applications is increasing.

Jump in chemical use

In the US, total herbicide use on soybeans increased from 56.4 million pounds in 1995 to 75.2 million pounds in 2000, according to chemical usage summaries from the National Agricultural Statistics Service of the United States Department of Agriculture (USDA 1991).

The use of glyphosate (Roundup) increased from 6.3 million pounds to 41.8 million pounds in the same period.

In 1995, glyphosate was used on a fifth of the soybean crop. But by 2000, just 4 years after the 1996 release of Roundup-ready soybeans, it was used on 62% of the crop (Tengnas and Nilsson 2002). Furthermore, applications increased from one per crop to 1.3 applications.

In the danger zone – Brazilian Amazon River floodplains

There is concern (but not yet evidence) that agrochemicals will contaminate lakes and lagoons in the Brazilian Amazon River floodplains. These agrochemicals include the herbicides trifluralin (Treflan), lactofen (Cobra), fomesafen (Reflex), bentazon (Basagran), imazethapyr (Pursuit), sethoxydim (Poast) and clethodim (Select).

During the dry season, the waterways dry up and any contamination in the separate water bodies would become more concentrated (Fearnside 2000 and Leibold 2001a). In the Brazilian Amazon, high humidity and heavy rains have already caused fungus and blights to spread. This, in turn, has increased use of fungicides.

Similarly, as production continues in the same area over a number of years, pest populations will increase, meaning increased use of chemical controls. Because Brazil has no frost, pests will adjust more rapidly to whatever chemicals are used to prevent them than they do even in the United States, where pests have rapidly developed resistance to the chemicals used to control them.

Soybeans’ massive share in chemical use

The Food and Agriculture Organization and others estimate that a quarter of all pesticides used in Brazil are used in soybean cultivation, and that in 2002 Brazilians used 50,000 metric tonnes of pesticides on soybeans (World Bank 2002). Because of the rapid expansion of area planted with soybeans, pesticide use is increasing at a rate of 21.7% per year.

Soybean production is expanding into areas where there aren’t enough people to work on plantations, so pesticides are used to reduce labour needs and costs. Areas planted with soybeans are becoming larger and so using machines makes the application of pesticides more cost-effective.

More work needs to be done to analyze the full range of agrochemicals used to cultivate traditional and genetically modified soybeans. We also need to look at agrochemicals’ long-term effects on the environment and the development of resistance to them.

Credits

Extracts from "World Agriculture & Environment" (2004) by Jason Clay

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