Are U.S. Crop Yields Declining?
Most of Them Aren’t, But Yield Growth Remains Critical
By Emma Kovak
For years, climate activists have pointed to the threat of declining crop yields as a reason to pass the most aggressive climate policies. Some poorly framed research papers and bad media coverage have fed this fire. But, despite an already warming climate, crop yields have continued to grow. Despite more than a half century of increasing temperatures, yields in the U.S. and around the world—especially for key cereal crops like corn, wheat, and soybeans—have crept higher and higher. In September, USDA forecasted record high yields for corn and soybeans for 2025.
But, while crop yields are definitely not going down in the near term, there is some potential to be concerned: the rate of crop yield growth, or, how fast crop yields are increasing, appears to be slowing for some key crops. From 1961 to 2025, U.S. corn yields increased from just under 2 metric tons per hectare to just under 6 metric tons per hectare. That works out to an annual growth rate of 117 kg per hectare per year. But, if you isolate just the last decade—2015 to 2025—U.S. corn yields only grew, on average, by 16 kg/ha/yr.
If the past decade truly marks a slowdown in U.S. corn yield growth, then this is something we should all care about. Increasing crop yields—especially for staple crops like corn—is critical for food security, environmental sustainability, and the stability of the American farm economy. As the global population increases, crop yield growth can assure that humanity can produce enough food without converting more and more land to agricultural production. Since 1961, for example, increased crop yields saved over 1.8 billion hectares of land from conversion to agriculture—an area of land larger than Russia. Yield growth is also key to keeping food affordable, and to combatting further food price inflation in the U.S. and around the world.
Thankfully, though, the evidence to date does not support the claim that key crop yields are facing a long-term trend that signals declining growth rates. While there is evidence of yield declines in some U.S. crops—mainly for specialty crops like fruits and vegetables—these are not as pressing as the potential slow down in growth for key cereal crops. Nonetheless, policy steps can and should be taken to reverse any negative yield trends in specialty crops, and to avoid any risk of a slowdown in yield growth in key crops.
Long-term yield growth in corn is probably not slowing down
While some believe this last decade of slower U.S. corn yield growth is the start of a long-term trend, they ignore the actual causes of the reduced growth rate: short-term poor weather conditions, and other factors, like farmers expanding onto marginal land.
Corn yields in the U.S. have been on a clear long-term linear trend since at least 1961, increasing by an average 117 kg/ha every year (black trendline in graph below). But, over that same period, there have been numerous decade-long periods where corn yields have increased either faster or slower than the roughly 60 year average. From 1978 until 1988, for example, U.S. corn yields only increased by 27 kg/ha/year, and from 2000 until 2010 corn yields increased by 178 kg/ha/year (dashed red lines in graph below). This is all natural variance.
Some researchers argue that the current period of slower growth is climate change finally taking its toll. However, this current “slowdown” is still within the range of similar historical periods, so we do not yet know whether it indicates a coming larger change to the long-term trend, or is, instead a short-term trend dependent on a few bad years within the last decade.
Historically, many periods of slower yield growth have been caused by poor growing conditions, mainly due to bad weather. For example, 1960–1972 had particularly favorable weather, followed by poor conditions—especially in 1980, 1983, and 1988. Over the last 10 years, weather conditions for growing corn were bad in 2019 (too much rain), 2020 (derechos), and 2022 (drought and high heat), contributing to the current slowdown in yield growth. All of these poor weather factors are relatively common, for example part of Iowa experiences a derecho every 1 to 2 years though they vary in severity. Some researchers think that climate change will increase the frequency and severity of weather events like derechos, but others are still assessing long-term trends.
But just because these periods of slower growth don’t last doesn’t mean we shouldn’t continue improving crop resilience to years with bad weather or other factors that slow yield growth. Even if the long-term yield growth trend continues, years with worse yields still negatively impact farmers and consumers.
Yields for some U.S. crops have actually declined
Although corn yield growth has slowed down in the U.S., corn yields, importantly, have not actually declined. Across the four top crops in the U.S.—corn, soybeans, wheat, and cotton—yield growth has remained fairly constant over the past 60 years. That is, yields have increased by factors of 2 to 3.
But when it comes to other crops, U.S. yields have not been as steady. Of the top four vegetable crops—potato, sweet corn, lettuce, and tomato—yield growth has slowed in two—lettuce and tomato—and yields have actually declined in one—lettuce.
And if you look at yield trends in other specialty crops, there are a number of examples of American crop yields actually declining in the last decade.
These yield declines are concerning, but the reasons for each vary.
The recent decline in strawberry yields shown above may be due to hotter temperatures in the main California growing regions, though it is so far a very short-term trend and may not continue.
Sweet potato yields plummeted in 2018 due to hurricane Florence, and yield declines in 2016, 2021, and 2022 align with increases in cultivated area, likely expanding to include marginal lands.
The decline in spinach yields is at least partially due to expansion in organic spinach production. Based on USDA NASS data for conventional vs organic production,, in 2016, organic spinach production made up 30% of all acres harvested, and by 2021 had reached 42%; and though organic spinach yields increased about 30% during that time they were still 37% to 52% lower than yields for all spinach production.
The dramatic decline in orange yields is largely due to the devastating impacts of citrus greening disease in Florida, which used to produce the majority of U.S. oranges. First detected in 2005, citrus greening had spread throughout Florida’s growing areas by 2008. On average, orange yields were higher in Florida than California from about 1987 to 2010, but California has now become the largest orange producer in the U.S. California has implemented strict quarantine measures to prevent the spread of citrus greening disease into the state. Continued research is needed on treatments for citrus greening, though some promising treatments have been identified so far.
Addressing slowdowns in yield growth and declines in yields
Though the causes of specific periods of slower than average yield growth vary, the long-term drivers of yield growth are well understood and should be prioritized—these include R&D funding combined with public farm extension programs, and technologies like crop breeding, farm machinery, and chemical and biological inputs.
Historically, public R&D funding has supported increases in agricultural yields, but U.S. government spending on agricultural research has declined by a third from 2000 to 2020. A 2023 study commissioned by The Breakthrough Institute estimated that doubling U.S. public investment in agricultural R&D could boost agricultural output by 69.5% by 2050—roughly 40% higher than under a business-as-usual scenario.
Crop breeding and genetic modification—or broadly genetic improvement—are also supported by public R&D. Some upcoming genetic technologies have the potential to contribute to future yield growth, including short corn varieties and hybrid wheat. Bayer, along with a smaller gene editing company called Pairwise, recently developed new varieties of shorter corn plants that are less prone to breaking under high winds and could address yield loss to events like the 2020 derechos. Similar to this short corn technology, dwarf wheat and rice contributed to yield growth during the Green Revolution.
Recently, Corteva claimed it discovered a new way to produce hybrid wheat that improves both yields and drought tolerance. Other organizations have produced hybrid wheat varieties, but the technology is difficult to scale in a cost-effective manner. Hybrid corn was another new technology central to the Green Revolution, alone responsible for 16% of corn yield gains in Minnesota between 1930 and 1980. Hybrid crops are made by breeding two different varieties of the same crop species, and the resulting seeds can have increased yields, stress tolerance, and other advantages collectively referred to as “hybrid vigor.” If viable, hybrid wheat technology could help continue growing wheat yields.
In addition to agricultural research and development, regulations for novel technologies also influence crop yield growth. Regulations can impact commercialization and adoption of everything from new genetically engineered crop varieties, pesticides, and drones. In order to enable use of new agricultural technologies to continue crop yield growth, regulations must be proportionate to risk and not unnecessarily hinder adoption.
On a global level, crop yields must continue to increase to meet the projected 56% rise in crop calorie demand by 2050 (and meat and dairy yields must meet the 70% rise in demand). Even if yields continue to grow at current rates, the world would still need to convert 600 million more hectares—an area the size of Algeria—to farmland in order to increase food production enough to meet demand. In order to prevent this land conversion, yields must increase even faster.