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Are GM crops better for the environment?

Are GM crops better for the environment?

In its second report on GMOs, The Canadian Biotechnology Network (CBAN) asks “Are GM crops better for the environment?” Here’s a short summary of what we found particularly interesting:

The first and major GM trait on the market is Herbicide-tolerant crops and herbicide use. Herbicide-tolerant (Ht) crops are genetically engineered to tolerate applications of a particular herbicide. This means that when farmers use specific herbicides on their Ht crops, the weeds are killed but the genetically modified herbicide tolerant crops survive. The emergence of ‘superweeds - weeds that are resistant to applied herbicides - causes two primary environmental impacts. The first is that farmers often have to till to control weeds that cannot be controlled with herbicides, which leads to soil erosion. The second is that farmers continue to use glyphosate, because it is a broad-spectrum herbicide, but also add other herbicides to control glyphosate-resistant weeds.

The second major GM trait on the world market is insect resistance. Insect-resistant crop varieties are engineered with genes from the bacteria Bacillus thuringiensis (Bt) to produce Cry protein endotoxins in their cells. This makes the plant itself toxic to some insects, such as butterflies and beetles. Bt plants produce a toxin that may have adverse environmental impacts, including on the soil and non-target organisms. The use of Bt crops as such can lead to the emergence of new, secondary pests.

Widespread use of herbicide-tolerant crops has led to an increased use of herbicides. Continual exposure to these herbicides has led to the emergence of herbicide-resistant weeds. The spread of these herbicide-resistant weeds is, in turn, further pushing up the overall use of herbicides. A similar pattern has developed in Bt insect resistant crop cultivation systems. This pesticide treadmill has serious impacts for the environment and human health.

Industry responses to weed and insect resistance problems focus on replacing one pesticide with another and on replacing GM seeds with other seeds that are genetically engineered to be tolerant to other herbicides and to produce multiple Bt toxins.

Biological, ecological and social systems are interrelated and interdependent. Understanding how the release of GMOs affects all these systems is complex, particularly because there may be a time lag between the release of a GMO into the environment, and any observable impacts. The full impacts on the environment cannot be predicted. Three major concerns are raised: Herbicide-tolerant systems and their impact on soil conservation, the effects of BT crops/GM on biodiversity and the contamination of non-target organisms.

One of the advertised benefits of using Ht crops is to allow farmers to use no-till management systems, which are better for the environment because they prevent soil erosion and preserve organic matter. Herbicide-tolerant cropping systems replace tilling the soil to remove and kill weeds, with the use of herbicides. Such no-till practices therefore encourage herbicide use, and the fact that weeds are not removed or killed by tilling, can encourage the emergence of herbicide-resistant weeds.

Scientists have observed that Bt crops can negatively affect soil organisms, many of which are important for soil health and for helping plants absorb nutrients from the soil and resist disease.

Conserving biodiversity is an essential part of sustainable agriculture and is beneficial from both an economic and ecological perspective. Ht crop systems have encouraged the use of herbicides that reduce overall plant diversity in agricultural systems, and in doing so, can limit habitat and food sources for other important organisms such as bee and butterfly species.

Agrobiodiversity is important for a number of reasons. A large proportion of biodiversity around the world can be found in agricultural landscapes, and it supports other diversity off the farm. Plant and crop diversity, for example, is necessary for pollinator and bird diversity, which in turn supports species that may act as natural predators for pests and diseases.

Agrobiodiversity is closely related to food security, and is key to our ability to adapt our agricultural systems to a changing climate. Industrial agriculture has encouraged shifts to growing a small number of varieties in large-scale monocultures. Large corporations focus on developing and selling these few varieties, which are bred for uniformity, and focus on characteristics such as storability, transportability and yield, often at the cost of other environmental adaptations. In addition, the shift to hybrid and proprietary seed varieties (including GM seeds under patent protection) has meant that many farmers buy seed every year, and do not save their own locally adapted seed. GM seeds and crops are a product of this approach to agriculture, and have perpetuated the loss of agrobiodiversity.

Climate change is going to increase the need for crops that have diverse and resilient genetics, and that are able to adapt rapidly to changing conditions. Major seed companies around the world have patented gene sequences to genetically engineer “climate-ready” crops that could respond to environmental stresses. However, a number of studies have already found that traditional varieties perform better than modern ones in stressful or extreme conditions (see page 30 for more information).

The full version of CBANs second report is accessible via this link here or through CBANs website.


Link to first report:

Link to second report: