Are Soybeans Driving Deforestation?

And is chicken off the menu?

Combines to harvest soybeans sit at the Morro Azul farm about 70km from Tangara da Serra , Mato Grosso, Brazi
Combines to harvest soybeans at the Morro Azul farm 70km from Tangara da Serra, Mato Grosso, Brazil.

 Paulo Fridman/Corbis via Getty Images

People have many reasons for eating less meat; since I am trying to live what's called a 1.5 degree lifestyle, I look at the carbon footprints of various foods and eat almost no beef (according to Our World in Data, beef has 36.44 kilograms of CO2 emissions per 1000 calories), a fair bit of chicken (5.34 kilograms/1000 calories) and a lot of tofu (1.17 kilograms/1000 calories).

Treehugger usually takes the stance that one shouldn't eat meat at all; that to really get to a low carbon diet, one has to go vegan, since milk and cheese have a bigger carbon footprint than pork or fish. However, the graph in this tweet from Hannah Richie of Our World In Data gives one pause about even eating chicken.

In a post on soy, Ritchie describes how soy production has exploded over the past 50 years, and has doubled in this century.

Soybean production
CC Our World in Data

And, as the graph from the tweet shows, (larger version here) three-quarters of it is being fed to animals. A lot of that is fed to pigs, but fully 37% of all the soybeans in the world are fed to chickens. Only 6.9% is turned into tofu, soy milk, and other soy products. Chicken sales were up too; according to Poultry World, almost 20% last year, as more people were cooking at home during the pandemic.

In her post, Ritchie goes on to address the question of deforestation, most of which is driven by cattle rather than soy production, but notes that there is an indirect connection. This is a subject my colleague Katherine Martinko covered earlier in her post titled Fast Food Is Fueling Brazilian Wildfires, with the subtitle, "When you buy a burger, it could be from a cow raised on Brazilian soy feed. That's a problem." Perhaps she should have specified a chicken sandwich instead, given how small the percentage is that goes to beef.

Coincidentally, I have been reading Vaclav Smil's latest book "Grand Transitions," one of which is the transition happening in agriculture. He writes that "the most decisive development in modern food production has been its transformation from an endeavor powered solely by photosynthetic conversion of solar radiation to a hybrid activity that has become critically dependent on rising inputs of fossil fuels and electricity."

We don't really eat food that is grown with the energy of the sun, but from the energy of the fertilizers made from natural gas, the diesel that runs the equipment, and the trucks that ship it all over the world. Smil adds it all up (although soybeans fix nitrogen so they need a phosphate fertilizer); and concludes that when you are eating chicken, you are basically eating diesel fuel.

"Energy cost of modern meat production is always dominated by the cost of animal feed. To produce a single breast of 170 grams, a broiler chicken had to consume about 600 grams of feed, or roughly 8.7 MJ, and in volume terms that would be equivalent almost exactly to a cup of diesel fuel. The total energy cost of meat must be enlarged by 10–30% in order to account for direct uses of electricity and liquid and gaseous fuels to heat, air-condition, and clean the structures housing the animals. Additional energies are required to move traded food and feed."
Smil conversion of energy to make meat
Animal feeding ratios 1909-2019. USDA

Chicken is the most efficient converter of food energy into meat, thanks to its fast growth rates, short life spans, and breeding changes that have reduced the amount of food needed down to 1.8 kilograms of food per 1 kilogram of meat. That's why chicken has become so affordable compared to other meats. But we are eating a lot of chicken, and that's driving a lot of soybean production, and directly or indirectly, that is burning fossil fuels and driving deforestation.

If we just ate that tofu directly instead of converting diesel and soybeans into chicken, we wouldn't need 77% of those diesel-powered soybeans and could reforest or afforest that land, turning it into a carbon sink instead of a source. And that's not chickenfeed.

View Article Sources
  1. "Greenhouse Gas Emissions Per 1000 Kilocalories." Our World in Data, 2021.

  2. Ritchie, Hannah. "Soy." Our World in Data.

  3. McDougal, Tony. "US Poultry Meat Consumption Rises: Chicken Protein Of Choice." Poultryworld, 2020.

  4. Smil, Vaclav. Grand Transitions. Oxford Univ. Press U.S., 2021.