Soy story

What went wrong with genetically modified soybean? (9 minute read)

I admit it, I’m finding it difficult to imagine my diet without meat. Although I’ve been uncomfortable about eating meat at times in the past, most often for animal welfare reasons, until recently I never made much progress in cutting down. In the last year, I’ve been trying harder, motivated partly by health, but more by my growing understanding of the impact of meat consumption on climate change.

I’ve written about this issue before, so I won’t go into the problem in detail. In summary, there are two main problems with meat. Firstly, meat is an inefficient way to produce nutrients. Three quarters of the world’s agricultural land is devoted to livestock (both meat and dairy production). Despite this, meat and dairy together only contribute less than 20% of the global calorie supply. Secondly, cattle, sheep and goats are especially bad for the climate, because their digestive systems belch methane. These two factors have combined to convince me to consider meat as more of a treat than an everyday food.

But I’ve noticed something as I cut my meat consumption. Quantities of certain other foods have increased. I’ve been eating more chickpeas and lentils, and soybeans have been sneaking their way in too, in the form of tofu and various “fake meat” products like vegetarian sausages. I know that the statistics tell me that these foods are much better for the climate, but I’ve got some nagging doubts. New Zealand produces very little of these crops, which means we are relying on overseas production. Soybean, in particular, is associated with intensive agriculture, and I’m wondering just how sustainable it really is.

As its name suggests, soybean is a type of bean, a member of the legume family of plants. Specifically, the soybean is the seed of the soy plant (also known as Glycine max), which grows as a bush 1-2 metres high. It is related to other important crops like peas and beans, but also to chickpeas, lentils, clover and even gorse.

Soy has a long history of cultivation, with evidence suggesting that it was domesticated in China at least 4000 years ago, perhaps much earlier. It was introduced to Europe and the Americas around the 18th century, but it’s really only in the 20th century that it became a major crop. In the 1960s, global production was approaching 50 million tonnes, with most of that produced in the USA. By 2020, that figure was around 350 million tonnes, with the USA and Brazil the main producers and Argentina a distant third. The areas involved are staggering too. In the USA alone, there were 338,000 square kilometres planted in soybean in 2016. In comparison, the total land area of New Zealand is only around 270,000 square kilometres.

To put the figures into context, global maize production is in excess of a billion tonnes, while wheat and rice are in excess of 700 million tonnes. So soybean is not the biggest crop, but it’s certainly important.

Like maize and wheat, the soy plant grows as an annual, which means that it is harvested in the same year as it is planted, and once it has produced its seeds, the plant dies. Every year, every crop of soybean has to be planted anew. How soybean is produced depends very much on where it is grown, but soybean production is highly mechanised, with seeds planted and harvested using enormous machines (there’s a video showing soybean production in Canada linked here).

Photo by Kelly Sikkema on Unsplash

One of the troubling aspects of soy production is its link to deforestation. It doesn’t take long to find reliable sources stating that soy production in Brazil and Argentina is resulting in deforestation. Since deforestation is an important contributor to climate change, at first glance I wonder whether shifting my diet away from meat and towards more soy is really a good thing.

Look more closely, however, and things become clearer. Less than a quarter of the global soybean crop is eaten by people directly. Only 7% is used for products like tofu and soy milk, while around 18% is used to produce oil (most of which is eaten, but some of which is used for biofuel). On the other hand, more than three quarters of the global soy crop is fed to animals. So, my vegetarian sausages and tofu are not the problem – the problem is the meat that I eat, especially chicken. If we ate more soy and less meat, the demand for soy would actually go down. Once again, I’m pointed to the conclusion that reducing our meat consumption is crucial.

But there’s another aspect of soybean production that has prompted concern, and it is worth a closer look. The majority of the soybean grown worldwide has been genetically modified. In the USA, 95% of the soybean grown is genetically modified. In Brazil, the figure is even higher.

Soybean was one of the first food crops to be genetically modified, with the first variety released in 1996. This was the so-called Roundup Ready soybean, resistant to the herbicide glyphosate, which was sold under the name Roundup. A soybean that was resistant to herbicide allowed farmers to control weeds in their fields without having to worry about the herbicide harming their crop. Roundup Ready soybean, and other Roundup-resistant crops that followed, became the most rapidly-adopted technology in the history of agriculture. Within 15 years, three quarters of the global soybean crop had this trait, and in the USA the figure was greater than 90%. Roundup Ready soybean became the world’s most widely-grown genetically modified crop.

Back when I worked on managing invasive weeds for the Department of Conservation, glyphosate was valued because it could be used to control a wide range of weeds. Sometimes it was applied as a spray, but it could also be applied by cutting stems and then painting them directly with the herbicide, a method which minimised the amount of herbicide released into the environment. This was important, because most plants are susceptible to glyphosate, including the native plants that we were trying to protect. But, would glyphosate be applied with such care by farmers growing a resistant crop like Roundup Ready soybean?

From the earliest days of its use, there was a question about whether the repeated use of glyphosate on fields of soybeans and other crops would result in weeds developing resistance. This has been a problem with a number of herbicides, as well as other pesticides that control insects and fungi. The problem develops because when a pesticide is applied, a tiny proportion of the pest population may be less susceptible to the pesticide, and therefore survives and goes on to reproduce. Over time, repeated use of the same pesticide results in more and more of the less susceptible pest surviving and reproducing, until the pesticide is no longer effective. So far, more than 600 pest species have developed some degree of resistance to pesticides.

To avoid pests developing resistance, the best strategy is to vary the methods of pest control used, not just using different pesticides, but by using methods like alternating crops and using biological control. But the use of Roundup Ready crops encouraged reliance on glyphosate alone, a strategy which conventional wisdom suggested would result in weeds which were just as resistant to glyphosate as the Roundup Ready soybeans themselves.

Monsanto, who sold both Roundup and Roundup Ready soybean and therefore can’t be considered an unbiased judge, suggested that resistance was unlikely to develop. There were some arguments in their favour – glyphosate had been used for around 15 years prior to the introduction of Roundup Ready soybean with no signs of resistance developing, and the way it affected plant growth also made resistance less likely. Ultimately, though, they were proved wrong, and glyphosate resistance has now developed in more than 40 weeds.

The story of Roundup Ready soybean is a cautionary tale about genetic modification, but the problem wasn’t genetic modification itself. There’s no evidence that the glyphosate-resistant weeds picked up the trait from the Roundup Ready soybeans, and I’ve not found evidence of harm from the modified soybeans themselves. Rather, the problem was modifying the soybean in a way that would inevitably result in the overuse of glyphosate.

Although Roundup Ready soybean doesn’t sound as if it would have environmental benefits, it did have one crucial advantage over conventional soybean. Traditional methods of growing annual crops like soybean involve ploughing or tilling fields – an ancient method of preparing soil which helped to control weeds but was destructive to the soil. In recent years, new methods, termed “no-till” agriculture, have become more common. No-till agriculture is good for farmers, because ploughing uses a lot of fuel and labour, so by stopping ploughing they save money. But no-till agriculture helps fight climate change too. Not only does it use less fossil fuel, but it reduces the amount of carbon released from the soil into the atmosphere. Although the difference isn’t huge, it’s still a positive change. The trend to no-till agriculture has been a good news environmental story at a time when good news is badly needed.

Roundup Ready crops like soybean made it easier for farmers to adopt no-till agriculture, because they didn’t have to rely on ploughing to control weeds. But, if herbicides become less effective, does this mean that farmers will resort to ploughing again?

Unfortunately, it seems as if this may be the case. There’s evidence that some farmers in the USA are back to ploughing their fields to help with weed control as glyphosate becomes less effective. There’s also evidence that farmers are applying glyphosate at higher rates. But there’s another possibility – scientists are now developing soybeans which are resistant to other herbicides too. The result, though, is that now some weeds are resistant to multiple herbicides.

At first glance, the development of herbicide resistance in weeds may not seem like too great a problem. If the herbicides we have stop working, surely we can develop new ones? But it’s not as simple as that. Since the 1980s, there have been new herbicides, but they all work in the same way as older herbicides. This means that if a weed is resistant to the older herbicide, they’ll be resistant to the newer herbicide too. If we squander the herbicides we currently have available, soon we may not have any alternatives.

But as herbicide options become more limited, the need for them is increasing. Recent research has shown that weeds have a greater impact on soybean crops under conditions of drought and heat stress – conditions our crops will face with increasing frequency in the coming years. Scientists are now genetically modifying crops to better resist extreme weather such as droughts. But the lesson from Roundup Ready soybean is that the real challenge is not necessarily with the genetic modification itself. The challenge may be to make good choices in how to apply that technology.