Soybeans in a field ready for harvest

Plants that changed the world: soybean

War hero, global industrialist, maybe even supervillain – there are many faces to this versatile bean, finds Rob Reddick

You can eat it. You can drink it. You can raise livestock with it, plant it to fertilise land, or process it to make varnishes, soaps, inks – even explosives. Eat processed food and you’ll likely ingest it without even knowing. Yet live in the UK and you’ll probably never see it grown.

What is it? Soy (Glycine max), the world’s third most valuable crop – and arguably the most versatile.

Soy’s success

G. max is an annual, self-fertilising legume that can grow up to two metres tall. It’s valued for its resource-rich beans, which yield approximately 20 per cent oil and 40 per cent protein. The beans are principally sought after today because they’re a very cheap source of protein.

Soybeans have proved popular for millennia due to their flexibility as a food. They also offer great nutritional value, containing no cholesterol, low amounts of saturated fat, and good levels of fibre, zinc, iron and calcium.

As soy is a good source of all of the essential amino acids (those that cannot be made by the body itself, such as tryptophan, phenylalanine and hystidine – see our amino acid images for more information), it’s often a staple food for vegetarians (most people rely on meat as their source of essential amino acids).

However, G. max is actually classified as an oilseed. Its oil has dozens of culinary and industrial uses, and can even be used as a biofuel.

A further benefit is that, like many legumes, G. max fixes nitrogen, and so provides soils with nutrients.

The plant’s roots

Cultivated for at least 3,000 years in China and Japan, the bean first spread across East Asia as a useful food that could be eaten fresh or dried, fermented into soy sauce, or powdered and mixed with water to make milk (and then curdled to make cheese-like tofu).

It wasn’t until the mid-19th century that it really began to be noticed outside of Asia, and its modest early successes in the West weren’t as a foodstuff. Unable to tolerate the harsh frosts of northern Europe, the bean grew well in the USA, where it was planted for livestock to forage and to replenish nitrogen in the soil of cotton fields.

But by the 20th century, agriculturalists had discovered the bean’s high oil and protein yield, and so industrial use of soy oil accelerated (Henry Ford even made a car using soy-based plastics). Soy meal also started being used to bulk out food and make animal feed.

“Uncle Sam needs soybean oil to win the war”

It was World War II that really raised soy’s popularity. In the early 1940s, the US government, needing to replace plant oils and edible fats that could no longer be imported from Asia, implored farmers to “grow more soybeans for victory”.

Not only did the bean help feed wartime America and its allies, but its oils were used to glue US torpedo boats together and make foam for US Navy fire extinguishers. Soy became integral to America’s war effort. Between 1940 and 1946, US production of the ‘miracle bean’ tripled.

Working after the war to put the rest of the world back on its feet – and to sustain its thriving soy industry – the USA then exported soy and its products to foreign markets across the globe. This launched the widespread use of soy that we see today.

A flowering modern industry

Global soy production increased nearly ten-fold between 1961 and 2009, and is double in 2016 what it was in the mid-1990s.

But, while it is a common ingredient in processed food the world over, direct consumption of soy only accounts for a small fraction of what we grow; it is the global rise in meat consumption that is responsible for the skyrocketing of soy production.

85 per cent of soybeans are crushed into oil and meal, with almost all of the meal – 98 per cent – then being processed into high-protein animal feed. And with the popularity of meat continuing to increase as global prosperity rises, demand for soy is likely to grow even more.

Cutting down the beanstalk?

This soaring demand has come at a cost. Valuable habitats have been transformed into soy farms, particularly across the Cerrado and Amazon regions of Brazil. As well as disrupting ecosystems, the creation of vast tracts of farmland causes soil erosion, displaces people, induces climate change and drains water reserves.

A further problem is genetically modified (GM) soy, which has become very popular as growers look to increase their yields. GM soy is resistant to the herbicide glyphosate, so farmers can spray this weedkiller directly onto their crops, wiping out the weeds while the soy plants thrive.

But, over time, the intense use of glyphosate has led to ‘superweeds’ developing resistance, meaning that more of it has to be used to have an effect. The weeds in turn develop even stronger resistance, while our exposure to the chemical increases (or, even worse, farmers are driven to use more toxic weedkillers instead).

In fact, glyphosate use is now so common that it shows up in human breast milk and urine. And, while it was originally thought to be safe, scientists are beginning to investigate whether it causes cancer.

So, though our reliance on soy is showing no signs of slowing, there are likely to be some tough decisions ahead – this once-heroic bean’s popularity is already damaging the environment, and could also be damaging our health.

Lead image:

United Soybean Board/Flickr


Questions for discussion

  • What do you think is the best way to reduce our reliance on soy in the future?
  • Compare the soybean’s oil and protein content to other sources of protein. What do you notice?

About this resource

This resource was first published in ‘Plants’ in May 2016.

Ecology and environment, History
Education levels:
14–16, 16–19, Continuing professional development