Oat Milk vs. Almond Milk: Which Is More Environmentally Friendly?

Plant-based milk is a booming market, representing 15% of the entire milk category. And people are choosing vegan milk alternatives for many reasons—not least because of the lighter impact they have on the environment.

Data from the United States Department of Agriculture shows that nondairy milk sales increased by 36% in 2020, whereas cow's milk sales declined by 12%. But which is the eco-friendlier option of the two most popular varieties, almond milk or oat milk? 

To measure the environmental impact of a type of milk, one must consider a multitude of factors: where the crop grows, how much space it requires, how much water it uses, its dependence on chemical substances, plus the emissions generated by farming it, its production, transporting it, and so forth. It's a complex equation that rarely yields clear-cut results.

Still, it's important to understand how agricultural processes affect the planet. So, here's how oat milk and almond milk weigh against each other and which is ultimately more sustainable. 

Environmental Impact of Oat Milk

Oat milk was so novel in the mid-2010s that it wasn't even named in a comprehensive Mintel report on plant-based milk sales from 2012 to 2017. By 2020, though, it had become the second most popular type of milk alternative.

The beauty of oat milk is that its namesake cereal grain grows all around the world, from Russia to Australia, from Canada to Spain. Oats are inexpensive and generally considered sustainable. Growing them is good for the soil and requires few resources compared to growing other grains. 

Water Use

As a crop, oats require between 17 and 26 inches of water per growing season, with one growing season lasting four to five months. That's roughly the same amount of water required by soybean, rice, and potato crops. Barley, oats, and wheat are all cool-season crops. They're relatively conservative on water usage because they don't lose a lot of moisture from heat like summer crops.

One gallon of oat milk takes an estimated 13 gallons of water to produce, but that's just its embodied water content—not including the water used to turn the oats into milk.

To make any dairy-milk alternative, water is mixed with a main ingredient (be it a grain, legume, or nut) to liquidize it. For both oat and almond milk, that ratio is about one cup of oats or almonds to four cups of water.

Land Use

Oats are seeds that grow on long, leafy stems in open fields yielding about 67 bushels per acre. What's particularly great about growing oats is that the land can be used for other crops when oats are not in season. 

This process is called crop rotation, which not only makes use of the land year-round (therefore eliminating the need to clear more land for agriculture) but has also been shown to improve the quality of the land. Crop rotation increases nutrients in the soil and helps combat erosion. Alternating between deep and shallow roots helps to stabilize the soil, and the constant changeover deters pests and disease.

Another great benefit of oats is that they can grow in a range of environments and soil types. They've been known to tolerate soil pH levels as high as 6.0 and as low as 4.5. They grow abundantly throughout the Americas, Europe, and Australia.

Russia is the world's leading oat producer, followed by Canada, Australia, the U.K., Brazil, the U.S., Argentina and China. This wide distribution means oats don't have to travel far to get to someone's bowl (or in this case, cup).

Though the U.S. still sources some of its oats from Asia, South America, and Europe, more than half the oats Americans consume every year are grown on North American soil.

Greenhouse Gas Emissions

Growing oats around the world keeps greenhouse gas emissions from transporting them to a minimum. To be clear, the global oat trade is still thriving, but it hardly compares to that of soy (primarily grown in South America) and almonds (almost entirely hailing from California), which are its two plant-based milk competitors.

Data compiled by Columbia University's Climate School shows that oat milk has the lowest overall carbon footprint when compared to cow's milk, almond milk, and soy milk. A seven-ounce glass comes in at about 0.4 pounds of carbon dioxide. This figure factors in the emissions generated from farming the oat, harvesting it, and processing it into oat milk. What isn't included, however, is the emissions generated by the leftover pulp.

Unlike cow's milk, plant-based milks inherently generate byproduct through the process of turning plants into beverages. To make both oat and almond milk, the oats or almonds are soaked in water, blended, then strained to remove the pulp. If sent to a landfill, this pulp will produce methane, a greenhouse gas 80 times worse than carbon dioxide, as it rots. Thankfully, it's often used as livestock feed instead.

Pesticides and Fertilizers

USDA data from 2015 showed that fertilizers were applied to 76% of acres surveyed throughout the 13 top oat-producing states. Herbicides were applied to 51% of planted acres, fungicides to 9%, and insecticides to 4%.

Not all oats need these synthetic treatments to grow—as is proven by the Certified Organic label—but chemicals are still ubiquitous in grain growing, and they pose serious risks to affected ecosystems. In the U.S., pesticides affect more than 96% of all fish and 600 million birds.

Environmental Impact of Almond Milk

Almond milk remains the reigning champion of dairy-milk alternatives, accounting for a 63% share. The nutty beverage has dominated the market since 2013, when it surpassed soy milk in sales. The industry is worth $1.5 billion and grew by about 13% in 2021.

Almond milk appeals to the more health-conscious crowd because it contains only a third of the calories of oat milk, half the fat, and a half of the carbohydrates. However, sustainability-wise it's often criticized for its colossal water footprint and the fact that almonds grow only in one very small part of the world, California.

Water Use

Compared to oats and all other crops used for nondairy milk, almonds require an astonishing amount of water. The trees that produce these nutlike seeds need about 36 inches (twice the amount oats need) per season. That works out to roughly 1,300 gallons of water for every pound of almonds produced.

And because they only grow in hot, low-humidity environments, much of that water is "blue." As opposed to green water, which comes from rain, blue water comes from rivers and groundwater reservoirs. In California, where 80% of the world's almonds are grown, the ground has gradually sunk almost 30 feet over the past century due to depletion of underground aquifers.

With aquifers are being drained at a dangerous rate, negative effects are impacting nearby river ecosystems.

Land Use 

Almond orchards occupy 1.5 million acres in California's Central Valley, which is reportedly 14% of the state's irrigated farmland. Though almond orchards take up slightly less space than oat fields, one must consider that oats are generally rotated out every year to make room for other crops whereas almond trees live for 25 years and must be cared for year-round. This culture of monocropping provides no opportunity for ecological balance or biodiversity.

Another consideration: While oats can thrive in a range of conditions all over the world, almonds must grow in a very specific environment. 

Greenhouse Gas Emissions

Almond farming generates slightly fewer greenhouse gas emissions than oat farming—a kilogram of raw nuts generating a reported 1.6 kilograms carbon dioxide equivalent.

Yale University's School of the Environment says almond farming even has the potential to be carbon-neutral or carbon-negative because the coproducts of the almond industry (husks, shells, etc.) are valuable sources of renewable energy and dairy feed. Plus, almond trees temporarily store carbon throughout their 30-year lifespans.

However, it should be noted that post-production emissions—from transporting almonds between California and everywhere else in the world—can't be measured and are not included in the figure widely accepted as almonds' carbon footprint.

Pesticides and Fertilizers

Besides the major issue of water consumption, the second biggest environmental criticism of the almond industry is perhaps its reliance on harsh chemicals. The deciduous almond tree needs constant replenishment of nitrogen to thrive, and it receives it through fertilizers that leach into soil and pollute groundwater.

Moreover, almond trees are susceptible to disease and pest invasions (especially from the dreaded peach twig borer), and one of the best ways to protect them is with toxicants. In 2017, the California Department of Pesticide Regulation reported that 34 million pounds of pesticides were used on almond orchards that year—more than used by any other crop in the state. Herbicides, insecticides, and fungicides are used in large quantities just the same.

One of the insecticides widely used to ward off the peach twig borer, methoxyfenozide, is proven to be toxic to bees. Of course, almond trees depend on honey bees for pollination. A reported 1.6 million commercial colonies are brought to the Central Valley for a pollination frenzy every bloom season. And bloom season, as it happens, is the prime time to spray.

Which Is Better, Oat or Almond Milk?

In some areas, like land use and embodied carbon, oat and almond milk are neck and neck. In others, though, almond milk's environmental flaws far outweigh those of its grain-based counterpart.

Almond milk is far more demanding of water and, what's worse, only grows in a perpetually water-stressed region. That almond orchards are so geographically concentrated means the product must also travel great distances, generating more greenhouse gas emissions.

Then, there's the matter of animal exploitation. About 75% of the world's food crops require pollination, and almond orchards put extra stress on pollinators because it wakes honey bees from their winter dormancy two months early to pollinate while the trees are in bloom. Pesticides and insecticides that have been freshly sprayed on the trees threaten the health of these crucial pollinators whose populations are already in steep decline.

You can become a more sustainable nondairy milk consumer by buying Certified Organic and making sure the ingredients in your milk are ethically sourced. Shop local whenever possible or, better yet, go the package-free route and make your own plant-based milk at home.