American agriculture is at a crossroads. The farmers and ranchers who manage nearly 900 million acres of the United States produce food, fiber, and fuel with astonishing efficiency. Since the end of World War II, U.S. agricultural productivity has nearly tripled, enabling it to become the world’s largest food exporter. But all this efficiency has come at an enormous price. Just 1 percent of Americans are farmers but the sector produces 11 percent of the country’s emissions. Researchers are developing technologies and farming practices that can help minimize the climate impact of farming, and even turn farms into net carbon sinks. But federal support will be essential to getting these innovations through the farm gate, and to ensuring that changes are sustained over the long term.
Agricultural emissions present unique scientific and engineering challenges. The main greenhouse gases the sector produces – nitrous oxide and methane – are immensely powerful. Over 100 years, nitrous oxide has 270 times the warming potential of carbon dioxide, and methane nearly 30. Mitigating these gases, moreover, is not as simple as putting a scrubber on a smokestack or making a vehicle engine more efficient. Nitrous oxide is produced when soil microbes digest nitrogen fertilizers or animal manure, while methane is a natural byproduct of digestion in cattle, sheep, and other ruminant animals. These emissions, in other words, stem from human inputs to living ecosystems – ecosystems on which the entire enterprise depends.
One approach to reducing farm emissions, therefore, is to use those inputs more efficiently. A range of techniques – collectively referred to as precision agriculture – harnesses advanced sensors, data analysis, and farm equipment to do just that. In-field soil testing or remote sensing can help farmers assess the nutrients, organic matter, and water availability of their fields before they plant. During the growing season, farmers can use GPS-guided tractors to optimize their planting area, precision sensors can analyze plant growth, soil quality, and more in real time, and smart farm equipment can adjust pesticide and fertilizer applications based on what individual plants need. These techniques can improve efficiency by as much as 20 percent for some farmers, and wide adoption could cut emissions from the sector equivalent to 27 million metric tons of CO2 per year by 2030.
Farmers can also cut emissions by changing the inputs they use. Standard nitrogen fertilizers deliver a big burst of nutrition all at once, more than half of which is typically lost to soil digestion or runoff. Slow-release nitrogen fertilizers, however, are designed to provide nutrients over an extended timeframe. Reducing the amount of excess nitrogen in the soil means there is less nitrogen available to be converted to nitrous oxide. Other new formulations act on the soil itself, temporarily limiting the microbial and enzyme activity that breaks down nitrogen fertilizers. Proponents hope that, in addition to reducing emissions, they can also boost plant growth by keeping more nitrogen available in the soil. More research is needed, however, to demonstrate conclusively whether that is the case, and without a boost in yields farmers have little incentive to pay extra for these inputs.
A third approach to reducing agricultural emissions looks at the ecosystems side of the equation. Regenerative agriculture combines traditional farming practices with modern science to harness nature’s ability to refresh soils, reduce input use, and capture carbon. Farmers applying these practices might plant cover crops like clover or peas in between plantings of cash crops like corn and soy to protect the soil from erosion and to naturally fix nitrogen from the air. They might reduce or eliminate plowing to preserve soil structure and keep organic matter like roots and decaying leaves underground, helping the soil store both water and carbon. They might introduce livestock to provide natural fertilizers, or grow a wider variety of crops to prevent soil nutrient depletion and control pests. Scientists are still working to understand the carbon sequestration potential of these techniques, but proponents argue that it can transform farms into carbon sinks while improving biodiversity and saving farmers money in fertilizer and pesticide use.
Ranchers have a similar set of options for reducing methane emissions from their operations. Cattle growers can minimize carbon intensity through selective breeding, careful feed and pasture management, and better veterinary care. Scientists are also developing feed supplements that reduce the amount of methane generated in the digestive systems of cattle, sheep, and other ruminants, though they can be difficult to deliver for grazing animals. Other ranchers are turning to land management techniques that mimic natural ecosystems, which may increase carbon sequestration in pastures enough to balance the emissions from the cattle that graze them.
All these techniques require farmers to invest in new equipment, learn new skills, hire additional labor, or some combination of the three. In an industry already facing rising land costs, volatile crop prices, and oftentimes negative real incomes, that can be a tough sell. Today, just 5 percent of U.S. cropland uses cover crops and 21 percent uses no-till practices, and precision techniques are most common on large farms.
The Biden administration has taken important initial steps to encourage farmers down this road. The 2022 Inflation Reduction Act allocated nearly $20 billion to badly oversubscribed agricultural conservation programs, which should help expand their reach over the next five years. The U.S. Department of Agriculture also recently announced a $300 million investment in a Climate-Smart Commodities program, which will help farmers implement climate-friendly practices on their farms and create markets for the resulting products. But, these programs can only be a down payment. USDA conservation programs cover a little over 20 million acres of U.S. farmland today, or 2 percent of the total. To maximize the climate potential of U.S. farming, policymakers will need to think bigger than that.
Climate Security in Focus is a blog series dedicated to exploring key elements of climate security that impact American interests both at home and abroad. The series aims to examine specific aspects of climate security issues in order to better understand the challenges, facilitate conversation, and generate ideas.