Potential for U.S. Agriculture to Be Greenhouse Gas Negative

Posted on December 18, 2024 by Abby Hansen

Carbon is the foundation for agricultural products beginning with the conversion of carbon dioxide into sugar through the process of photosynthesis and ultimately converted into compounds that are harvested through grains, fruit, vegetables, nuts, and fiber and animals convert into meat, milk, eggs, or wool. Carbon dioxide is released back to the atmosphere through processes associated with agricultural production along with methane from enteric fermentation in ruminants and nitrous oxide from nitrogen fertilizer use (Figure E1). These three comprise the greenhouse gases (GHG) that impact the environment. Currently, GHGs from agriculture represent about 10% of total emissions from all economic sectors in the United States[1]. One of the goals is to reduce these emissions. This report explores U.S. agriculture’s opportunities in GHG reduction for the benefit of producers, society and the environment.

Figure E1. The carbon balance and GHG emissions are a result of the way all components of the system are managed.

The carbon cycle in modern agriculture is complex (Figure E1). Agriculture is a dynamic and complex system; however, there are five major areas that offer opportunities to reduce the carbon footprint of agriculture. These are:

  • Soil carbon management
  • Nitrogen fertilizer management
  • Animal production and management
  • Crop production and the yield gap
  • Efficient energy use in agriculture

Within each of these broad categories, there are a number of currently available practices and emerging technologies that can positively impact emissions while improving both production and profitability. For example, within soil carbon management, the goal is to increase sequestration; however, this can be the result of a suite of regenerative agricultural practices, (e.g., reducing tillage intensity, increasing crop diversity, adding cover crops, maintaining continuous cover over the soil surface, and integrating livestock and manures to the cropping system). The impact of these practices is not confined to increasing soil carbon sequestration; but it extends to expanding nutrient and soil water availability for the crop. The combination of those effects increases crop productivity, reduces the yield gap and decreases the energy requirement for crop production when less tillage is used in the production system.

Nitrogen fertilizer management is aimed toward decreasing nitrous oxide emissions through practices that enhance nitrogen use efficiency like the 4Rs (right place right time, right form, and right amount); but it is also linked to changes in soil carbon management which affects the soil water dynamics. Soil water, along with the amount of nitrogen present in the soil, is a major factor affecting nitrous oxide emissions. Nitrous oxide is 300 times more impactful than carbon dioxide; so, a slight reduction in emissions significantly impacts agriculture’s overall emission profile. The opportunity areas for nitrogen fertilizer management are based on interactions among carbon, water and nitrogen.

Similar interactions extend to animal production and management because these systems are comprised of feed production and animal feeding, housing and manure management. Crop production management systems that reduce the carbon footprint of grain transfers into and utilization of high-quality animal feeds affect methane release which is 30 times carbon dioxide impact. These interactions reduce ruminant emissions. Improved animal housing reduces the energy requirement and use of carbon-based sources of energy.

A team of scientists identified the current practices and emerging technologies with the most potential for reducing GHGs based on their comprehensive analysis of scientific literature, computer simulations, and life cycle analysis estimates. These are shown (Figure E2) using two scenarios: 1) a medium impact if 50% of farm operations (as a percentage of total U.S. farm land area) adopted the practices, and 2) an aggressive impact if 75% (as a percentage of total U.S. farm land area) utilized the practices. Implementation of these five opportunity areas can have a large impact on agriculture’s GHG footprint.

Figure E2. Most Impactful Practices for Reducing Greenhouse Gas Emissions in Agriculture

A future agriculture will look different than today (Figure E3). Achieving this goal will require an assessment of individual farms and production systems to determine the most effective strategies along with the technical and financial support to implement practice changes. On-farm research and demonstration of these practice changes are needed to ensure efficacy and impact on profitability and sustainability.

Agriculture will benefit from understanding the dynamic relationship between GHG emissions and the practices and technologies with the most reduction potential and direct benefit to producers. Adopting deployable practices and emerging technologies provides opportunities that would benefit all aspects in agricultural production.

Figure E3. The agricultural carbon and GHG emission cycle with practices that have been shown to change the carbon dynamics, would benefit all aspects in agricultural production.

The above is taken from the Executive Summary of the “Potential for U.S. Agriculture to Be Greenhouse Gas Negative” report published by the US Farmers and Ranchers in Action (USFRA) and the Council for Agricultural Science and Technology (CAST). Click here to read the full report.

CGLR’s business and sustainability network programming is supported by the Fred and Barbara Erb Family Foundation.