Agricultural Emissions for Beginners: What they are, where they come from, and why they matter
- Anantha Peramuna, PhD
- 4 days ago
- 6 min read
Updated: 4 days ago
Why Agricultural Emissions Matter
Agriculture plays a critical dual role in the modern world. It feeds the global population but also contributes significantly to climate change. Agriculture is responsible for approximately a quarter of the greenhouse gases humans generate, making it one of the largest contributors to global warming.
For professionals responsible for sustainability reporting or managing supply chain data, agricultural emissions often represent a significant blind spot. They’re upstream, fragmented, and difficult to quantify, but increasingly, they are at the center of carbon footprint reporting, Scope 3 emissions, and climate strategy.
This guide aims to provide a clear introduction to:
What agricultural emissions are
The gases involved and how they differ
The main sources within agriculture
Why these emissions matter for sustainability goals and product-level impact
What Is CO₂ Equivalent—and Why Does It Matter?
Not all greenhouse gases trap the same amount of heat in the atmosphere, and they don’t persist for the same length of time. Methane, for example, traps approximately 25 times more heat than carbon dioxide over a 100-year period. Nitrous oxide traps nearly 300 times more.
To make comparisons easier, emissions are often expressed in carbon dioxide equivalent (CO₂-eq). This unit converts the warming potential of any greenhouse gas into the equivalent amount of CO₂. For instance, if enteric fermentation produces 2.85 gigatonnes of CO₂-eq, that means it has the same warming effect as 2.85 gigatonnes of carbon dioxide.
Using a common metric simplifies reporting, policy, and target-setting. It’s the basis for carbon footprinting, life cycle assessments (LCAs), and greenhouse gas protocols.
Getting to Know the Key Greenhouse Gases in Agriculture
Carbon Dioxide (CO₂)
Warming Potential: Baseline (1x)
Atmospheric Lifetime: Hundreds of years
Main Sources: Burning fossil fuels, deforestation, land-use change
Although CO₂ is less potent per molecule than methane or nitrous oxide, it is emitted in much larger quantities and remains in the atmosphere for a long time. In agriculture, CO₂ emissions mainly come from machinery (tractors, irrigation pumps), land clearing (cutting down trees or disturbing soil), and fossil fuel use in transport or processing.
Methane (CH₄)
Warming Potential: Approximately 25 times that of CO₂
Atmospheric Lifetime: Around 12 years
Main Sources: Livestock digestion, rice paddies, manure decomposition
Methane is a short-lived but powerful greenhouse gas. Its primary agricultural sources are livestock digestion, especially in ruminant animals like cows, and flooded rice fields, which create anaerobic conditions that allow methane-producing microbes to thrive.
Nitrous Oxide (N₂O)
Warming Potential: Approximately 298 times that of CO₂
Atmospheric Lifetime: Around 114 years
Main Sources: Soil fertilization, manure application, crop residue breakdown
Nitrous oxide is one of the most potent greenhouse gases, and it's predominantly generated when nitrogen-rich fertilizers break down in the soil. Manure and decomposing crop residues also contribute, particularly in wet or compacted soils where microbial activity transforms nitrogen into N₂O.
Biogenic Carbon Dioxide (CO₂)
Warming Potential: Not counted as fossil CO₂, but still affects cycles
Main Sources: Plant decomposition, animal respiration, manure, crop residues
Biogenic CO₂ originates from natural biological processes. For example, plants absorb CO₂ as they grow and release it when they decay or are consumed. In theory, this forms a balanced cycle. However, when biological processes are intensified—such as through large-scale manure storage or forest clearing—this balance is disrupted.
Protocols like the GHG Protocol require biogenic CO₂ to be reported separately from fossil CO₂. It’s not considered carbon-neutral by default, and ignoring it can lead to underreporting of true climate impact.
Continue Learning
For a deeper dive into how agricultural data becomes actionable:
Major Sources of Greenhouse Gas Emissions in Agriculture
Below are the seven largest contributors to agricultural emissions, each with its own unique sources and challenges. Together, they represent the majority of direct agricultural emissions.
1. Land-Use Change (LUC)
Main Gases: CO₂, CH₄, and N₂O
Contribution: Approximately 10–15% of global GHGs (6–7.5 gigatonnes CO₂-eq/year)
Comparison: Equivalent to emissions from around 1.8 billion cars driven for a year
When forests and natural landscapes are cleared for agriculture, carbon stored in trees and soil is released into the atmosphere. This not only increases CO₂ levels, but also reduces the land’s capacity to absorb future emissions. Land-use change is a major driver of long-term climate imbalance.
2. Enteric Fermentation in Livestock
Main Gas: Methane (CH₄)
Contribution: Approximately 5% of global GHGs (2.85 gigatonnes CO₂-eq/year)
Comparison: Similar to emissions from about 678 million cars annually
Ruminant animals like cows, sheep, and goats produce methane during digestion, a process known as enteric fermentation. While natural, the scale of global livestock production makes methane gas a major climate concern. Emissions can vary based on diet, breed, and animal health.
3. Manure Management
Main Gases: Methane, nitrous oxide, and biogenic CO₂
Contribution: Approximately 2% of global GHGs (1.34 gigatonnes CO₂-eq/year)
Comparison: Equivalent to emissions from 319 million cars per year
When stored or handled in anaerobic (low-oxygen) conditions, animal manure emits methane. As microbes process the nitrogen in manure, they also generate nitrous oxide. Though some CO₂ emissions are biogenic, they can still influence carbon dynamics at scale.
4. On-Farm Energy Use
Main Gas: Carbon dioxide (CO₂)
Contribution: Approximately 2% of global GHGs (1.03 gigatonnes CO₂-eq/year)
Comparison: Equivalent to emissions from 245 million cars per year
Energy is required for farming operations such as machinery use, irrigation, and electricity. When that energy comes from fossil fuels, it results in CO₂ emissions. Electrification, renewable energy, and efficiency upgrades are key levers for reduction.
5. Synthetic Fertilizers
Main Gases: Nitrous oxide (N₂O) and CO₂
Contribution: Approximately 2% of global GHGs (1.01 gigatonnes CO₂-eq/year)
Comparison: Similar to emissions from around 240 million cars per year
Nitrogen-based fertilizers increase crop yields, but they also lead to N₂O emissions when applied to soil. The production of these fertilizers is energy-intensive and emits CO₂ as well. Precision agriculture and optimized nutrient management offer reduction pathways.
6. Rice Cultivation
Main Gases: Methane and biogenic CO₂
Contribution: Approximately 1.2% of global GHGs (0.69 gigatonnes CO₂-eq/year)
Comparison: Equivalent to emissions from 164 million cars per year
Flooded rice paddies create oxygen-deprived environments, allowing methane-producing microbes to flourish. In addition, decomposing organic matter in fields releases CO₂. Intermittent irrigation or alternate wetting and drying can reduce emissions substantially.
7. Crop Residues
Main Gases: Methane, nitrous oxide, and biogenic CO₂
Contribution: Approximately 0.4% of global GHGs (0.23 gigatonnes CO₂-eq/year)
Comparison: Equivalent to 54 million cars driven for a year
After harvesting, leftover plant material like straw or stems decomposes in the field. If soils are wet or compacted, methane is emitted. If fertilized or rich in nitrogen, nitrous oxide is produced. Managing residue incorporation and soil conditions correctly is key to minimizing emissions.
Agricultural Emissions Sources at a Glance
Source | Main Gases | Global GHG Share | Equivalent in Cars per Year |
Land-Use Change | CO₂, CH₄, N₂O | 10–15% | 1.8 billion |
Enteric Fermentation | CH₄ | 5% | 678 million |
Manure Management | CH₄, N₂O, biogenic CO₂ | 2% | 319 million |
On-Farm Energy Use | CO₂ | 2% | 245 million |
Synthetic Fertilizers | N₂O, CO₂ | 2% | 240 million |
Rice Cultivation | CH₄, biogenic CO₂ | 1.2% | 164 million |
Crop Residues | CH₄, N₂O, biogenic CO₂ | 0.4% | 54 million |
Why Agricultural Emissions Matter to the Food Industry
For food companies looking to reduce their environmental impact, agricultural emissions are often the largest contributor to product-level emissions and the least visible.
Whether you’re coordinating data collection for a sustainability report or managing supplier documentation for retail clients, agricultural emissions form the backbone of your Scope 3 footprint.
Without consistent upstream data, it becomes difficult to:
Respond to client and investor demands for carbon footprint data
Identify high-impact suppliers or raw materials
Communicate emissions reduction progress credibly
Understanding these sources is the first step to integrating actionable insights into your sustainability and procurement workflows.
From Awareness to Action
Tools like life cycle assessments (LCAs) make it possible to quantify agricultural emissions at the product level. With the right data and guidance, companies can go beyond reporting and identify meaningful opportunities to reduce environmental impact.
Nature Preserve supports this transition by helping companies:
Estimate Scope 3 emissions from crops using national databases and certification data
Simulate farm-to-retail emission pathways
Turn complex environmental data into decision-ready formats
Ready to Build Your Scope 3 Strategy?
Whether you're just starting your carbon accounting journey or scaling internal decarbonization efforts, Nature Preserve is here to help.
Book a demo to see how we simplify agricultural data and deliver measurable insights without overwhelming your team.
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