How Agriculture Affects the Environment: Key Numbers

Farming changes the environment in six measurable ways, and the numbers are large. In 2022, US agriculture emitted 593.4 million metric tons of CO₂-equivalent, 9.4% of the national total, according to the EPA greenhouse gas inventory. Worldwide, agrifood systems produced 16.2 billion tonnes of CO₂-equivalent in 2022, 29.7% of all emissions, per FAO.

If you are asking how does agriculture affect the environment, the short list is: greenhouse gases, nutrient and pesticide runoff, water use, soil loss, forest clearing and lost habitat. This guide gives the best published figure for each, says who measured it and when, and ends with a calculator that shows how much nitrogen is left over on your own field. Years are the year of measurement, not the year you read this.

Six ways agriculture affects the environment

The table gives the scale of each effect side by side. Each row has its own section below with the source. The two emission rows use different boundaries: the EPA figure counts US farm production only, while the FAO figure counts the whole food chain, including land-use change and supply-chain activity.

These effects are linked. Nitrogen fertilizer that is not taken up by the crop can be lost as nitrous oxide to the air and nitrate to the water. Cleared forest releases carbon and then often turns into pasture. Bare soil washes into rivers. A change on one side usually moves another number on the other.

Chart

World agrifood emissions by stage

billion tonnes CO₂e, 2022, total 16.2

How to read these numbers

Three points stop the figures from being misread. First, the basis: the EPA counts greenhouse gases that leave US farms and ranches, using global warming potentials from the IPCC fifth assessment report. Second, the date: the 2022 inventory year is the latest one in the EPA report used here, and the World figures from FAO cover 2022 as well, so the US and world numbers can be compared. Third, the scope: a percentage of a national total says how big a sector is, not how much any one farm contributes.

The water and soil figures are different kinds of numbers again. Water withdrawal is a flow taken from rivers and aquifers. Soil loss is an average tons-per-acre estimate for cropland from a statistical survey, so it says little about a particular slope. Forest loss figures come from a satellite sample, not a full count.

Greenhouse gas emissions from farming

The EPA splits the 593.4 million metric tons of 2022 farm emissions into gases and sources. Nitrous oxide, mostly from soil that receives nitrogen fertilizer, manure and crop residues, was 308.0 million tons, about 52% of the total. Methane from cattle digestion, manure and rice was 276.8 million tons. The rest, 8.6 million tons, was carbon dioxide from urea fertilizer and lime (EPA inventory, chapter 5).

Chart

US farm emissions by source

million metric tons CO₂e, 2022, total 593.4

Agricultural soil management alone is the largest line, and cattle digestion is second. Beef cattle caused 71% of methane from enteric fermentation in 2022 and dairy cattle 25% (EPA). Rice paddies are a smaller source, 18.9 million tons, because flooded soil lets organic matter break down without oxygen and release methane. Letting a paddy dry out between floods can cut that. EPA names Arkansas, California, Louisiana, Mississippi, Missouri and Texas as the states where most rice emissions occur.

The EPA counts the electricity used on farms separately. Its sector overview says indirect emissions from electricity use in agriculture are about 5% of direct emissions (EPA, Sources of Greenhouse Gas Emissions).

US farm emissions are not falling quickly. They were 551.1 million tons in 1990, were highest, at 642.4 million, in 2018 among the years EPA tabulates and were 593.4 million in 2022. EPA publishes a new inventory each year, so check its page for a later year before you quote these numbers.

Farm emissions are only part of the food-chain picture. FAO splits the 2022 world total into three parts: 7.8 billion tonnes inside the farm gate, 3.1 billion from land-use change such as forest clearing, and 5.3 billion from processing, transport, packaging and other supply-chain steps. Land-use change emissions fell 30% between 2000 and 2022, while supply-chain emissions grew 52%.

Chart

US farm emissions, selected years

million metric tons CO₂e; years shown are 1990, 2005 and 2018-2022

Fertilizer, pesticides and water pollution

About half a million tons of pesticides, 12 million tons of nitrogen and 4 million tons of phosphorus fertilizer are applied each year to crops in the continental US, according to the EPA page (it gives no data year). The EPA says the National Water Quality Assessment shows agricultural runoff is the leading cause of water-quality problems in rivers and streams, the third leading source for lakes and the second largest source of wetland impairments (EPA, Nonpoint Source: Agriculture).

Nutrients that the crop does not take up move with rain and snowmelt into streams and groundwater. In lakes and coastal water they feed algae. When the algae die and decay, they use up the dissolved oxygen, and a low-oxygen “dead zone” forms. The EPA has documented over 165 dead zones nationwide, including Chesapeake Bay and the Gulf (EPA, nutrient pollution).

The Gulf of America dead zone measured about 4,402 square miles in the July 2025 survey, the 15th smallest in 39 years of measurement. The five-year average was 4,755 square miles, more than twice the Task Force goal of under 1,900 square miles by 2035 (NOAA). The nutrients come from the Mississippi River basin, which drains 31 states, and agriculture is one of several sources.

Pesticide runoff can harm aquatic life and fish-eating wildlife, and pollutants can reach groundwater. More than 13 million US households use private wells (EPA). Pesticide rules vary by product, crop and place: always follow the product label and your local rules, and ask your extension office or a licensed adviser about buffers and timing.

Phosphorus behaves differently from nitrogen. It binds to soil particles, so it moves mostly with eroded sediment and surface runoff, while nitrate moves with water through the soil and into tile drains and groundwater. That is why the same field can need runoff controls for phosphorus and timing controls for nitrogen. A buffer strip helps with the first and does little for the second.

Timing is the other lever. Nitrogen put on bare soil in autumn or ahead of heavy rain is more exposed to loss than nitrogen applied close to crop demand. Your state’s land-grant university publishes crop-specific guidance on rates, timing and setbacks near water. Many states also run cost-share programs for buffers and cover crops through USDA’s Natural Resources Conservation Service, so ask your local office what applies to your farm.

Two practical points follow. First, the amount of nitrogen left over after harvest, not the amount applied, is the part that can leave the field. Second, timing and placement matter as much as the rate. The calculator further down puts a number on the first point.

Freshwater use on farms

Agriculture is the largest user of fresh water. Globally, 69% of withdrawals go to agriculture, 12% to municipal use and 19% to industry. FAO counts irrigation, livestock watering and aquaculture as agriculture. The split is strongly pulled by a few countries with very high withdrawals: averaging each country on its own gives 59% agriculture, 23% municipal and 18% industry (FAO AQUASTAT).

Chart

Share of world freshwater withdrawals

percent, global ratios

The share varies by region. AQUASTAT puts agriculture at more than 80% of withdrawals in Africa and Asia and just over 20% in Europe. In Western Europe it is 5%, and industry takes 73%.

Taking water has two effects. Rivers and aquifers can be drawn down faster than they refill, and water that returns from fields carries sediment, nutrients and pesticides. AQUASTAT notes that most withdrawn water returns to the environment later, but its quality may be lower than when it was taken.

The usual fixes are drip or sprinkler irrigation in place of flooding, scheduling by soil moisture or crop stress instead of the calendar, and soil cover that lets rain soak in. Which one pays depends on your crop, soil and water price, so test it on one block first.

Water use also differs by crop and by season. A field of row crops in a humid region may need little irrigation in a normal year, while the same crop in a dry region may need several inches a month in summer. National or global shares therefore say how important agriculture is as a water user, not how much water your crop needs. Your own meter readings, soil moisture probes and a local irrigation guide give better numbers for decisions.

Soil erosion and land degradation

The 2017 National Resources Inventory reports that erosion on US cropland fell 35% between 1982 and 2017. Even so, water (sheet and rill) erosion averaged 2.67 tons per acre a year in 2017, and wind erosion 1.96 tons per acre (figures as reported by AgWeb from the USDA report; farmdoc daily, 2024, gives the same two figures). Averages hide wide differences between fields. A University of Illinois review compiled studies of conventional tillage in which erosion ranged from under 1 ton to over 7 tons per acre a year (farmdoc daily, 2024).

Worldwide, the IPBES assessment found that land degradation harms the well-being of at least 3.2 billion people. It names the expansion and unsustainable management of cropland and grazing land as the most extensive direct driver of degradation (IPBES media release, 2018). By 2014, more than 1.5 billion hectares of natural ecosystems had been converted to cropland (IPBES).

Erosion is also a cost to the farm, not only to the river downstream. Topsoil holds organic matter and nutrients, so losing it can mean buying more fertilizer to replace what washed away. The University of Illinois review notes that farmers can offset lost productivity by applying more inputs, which are costly. A field-by-field look at slope, residue cover and tillage will show where losses are likely to be highest.

The common countermeasures are reduced or no-till, cover crops, rotation and buffer strips. What they share is living roots or residue on the soil for more of the year.

▶ Seven simple ways to protect soil and water on a farm, explained in plain English. · 4:34

Deforestation and loss of habitat

FAO’s 2021 Global Remote Sensing Survey found that agricultural expansion drives almost 90% of global deforestation. More than half of forest loss is conversion to cropland and almost 40% is livestock grazing. Agriculture is the main driver in every region except Europe, where urban and infrastructure growth matter more. In Africa and Asia, over 75% of the forest area lost went to cropland, and in South America almost three quarters of deforestation is livestock grazing (FAO, 2021).

Clearing forest does two things at once: it releases stored carbon, and it removes a forest that would keep absorbing CO₂. It also removes the habitat of the species that lived there. This guide gives no single global figure for species loss caused by farming. IPBES (2018) names the expansion and unsustainable management of cropland and grazing land as the most extensive direct driver of land degradation, which it links to significant loss of biodiversity. For species data use the IUCN Red List and FAO’s forest reports for your region.

Several measures reduce clearing: planting under shade trees (agroforestry), leaving forest strips around cultivated plots, buyer rules that exclude produce from newly cleared land, and satellite alerts that flag clearing at the forest edge soon after it happens. Cocoa growers can find practical steps in our guide to sustainable cocoa farming techniques.

Forest clearing is also a land-record problem. Where a farm sits next to forest, a repeat satellite image shows when the edge moves, which helps owners, buyers and regulators check a claim that no new land was cleared. The images show that the cover changed, not who changed it or why, so records and a site visit are still needed.

How four kinds of farming compare

Impact concentrates in different places depending on what is grown. The table uses only the published US figures from this guide.

Dairy farms sit in two big categories at once, because digestion and manure both release methane and manure and fertilized feed crops add nitrous oxide. Practices cited in extension guidance for lowering emissions per unit of milk include better feed efficiency, manure digesters, managed grazing and feed additives under test. Rice growers can use drainage between floods, as above.

What reduces the impact on the farm

• Match nitrogen to crop need. Apply at the rate and time the crop can use. Split applications and soil or tissue tests help. Follow your state’s guidance and the fertilizer label.
• Keep soil covered. Cover crops, residue and reduced tillage cut erosion and runoff.
• Fit irrigation to the crop. Scheduling by measured soil moisture avoids water waste and drainage that carries nutrients.
• Manage manure. Capture methane with a digester where it is practical and apply manure at crop-need rates.
• Protect edges. Buffer strips beside streams filter runoff; forest strips protect habitat.

Each step costs money or labour, and the payoff differs between farms, so treat the list as options to test, not a ranked plan.

▶ Seven green farming technologies that save water, fuel and fertilizer. · 2:24

Calculator: how much nitrogen is left over on your field

Nitrogen that the crop does not remove can be lost to water or air. Enter your own numbers below. The default values are examples, not benchmarks and not a forecast. The calculator uses simple removal arithmetic: nitrogen applied minus nitrogen taken off in the harvested crop. It ignores soil nitrogen, manure credits, rainfall, tile drainage and timing, so it shows the size of the surplus, not how much will reach a stream.

Try the numbers for your own farm below.

How satellite monitoring can help

Every effect above responds to the same step: knowing what is happening in a specific field before it becomes a loss. Satellite images show vegetation vigour, bare soil and water stress across a field, so uneven growth or a poorly drained corner can be found early. They show where the problem is, not its cause, and a field visit or soil test still has to confirm it. Farmonaut Satellite + AI Farm Monitoring System is one tool that turns these images into field maps for growers.

▶ A real demo-account field where satellite passes show crop stress before it is visible on foot. · 1:42

How we checked the numbers

Every figure in this guide comes from a page we opened: the EPA greenhouse gas inventory and its water pages, FAO and its AQUASTAT water database, NOAA’s Gulf survey, the IPBES land degradation release and a University of Illinois review. The soil erosion averages are quoted from the 2017 National Resources Inventory as reported by AgWeb. Where sources use different boundaries, such as farm-only emissions and the whole food chain, we say so next to the number. Figures change when agencies publish new releases, so the year is shown beside each one.

Related pages on our site

More on this topic: carbon footprinting, fleet management, product traceability, satellite and weather API documentation, the satellite API and a farm monitoring sign-up page.

FAQ

How does agriculture affect the environment overall?

Through six main routes: greenhouse gases (9.4% of US emissions in 2022, EPA), nutrient and pesticide runoff, freshwater use (69% of world withdrawals, FAO), soil erosion (2.67 tons per acre a year by water on US cropland in 2017, per the USDA National Resources Inventory as reported by AgWeb), deforestation (almost 90% of it, FAO) and loss of habitat.

What share of greenhouse gas emissions comes from agriculture?

In the US, 9.4% in 2022, or 593.4 million metric tons of CO₂-equivalent (EPA). For the whole world, FAO puts agrifood systems, including land-use change and supply chains, at 29.7% in 2022.

How much fertilizer and pesticide is used on US crops?

About 12 million tons of nitrogen, 4 million tons of phosphorus fertilizer and half a million tons of pesticides a year across continental US crops, according to the EPA. USDA NASS publishes state and crop detail in its chemical use surveys.

Is agriculture the main cause of deforestation?

Yes, according to FAO’s 2021 remote sensing survey: almost 90% of global deforestation is linked to agriculture, with cropland above half and grazing almost 40%. The mix differs by region.

Which farm animals produce the most methane?

Cattle. In the US in 2022 beef cattle accounted for 71% of enteric methane and dairy cattle 25% (EPA).

Can satellite monitoring reduce the environmental impact of a farm?

It can help a grower see uneven growth, wet spots and stressed areas, so inputs and water go where the crop needs them. Satellite images do not measure runoff or emissions directly, and results depend on how the grower acts on what the maps show.

Conclusion

Agriculture’s effect on the environment is a set of measured numbers, each tracked by an agency on its own schedule. The US figures here are for 2022, 2017 and 2025; the world figures for 2018 to 2022. Check EPA, USDA and FAO for newer releases before you quote them.

The measures that move these numbers are documented: nitrogen matched to crop need, soil kept covered, irrigation matched to measured water need, manure handled well and forest edges protected. Measuring your own field is the first step, and the calculator above is a starting point. Rules on fertilizer, pesticide and water vary by place, so check local rules and take professional advice for your farm.