Crop Residue Burning and Its Detrimental Effects on Environment and Health

Every year, after the rice or wheat harvest wraps up, millions of farmers across South Asia, Sub-Saharan Africa, and beyond do something remarkably simple: they light their leftover crop residue on fire. It clears the field fast, costs almost nothing, and gets the land ready for the next season. But that wall of smoke rising from the fields carries consequences far beyond the farm – degrading the soil underneath it, loading the atmosphere with greenhouse gases, choking the air for hundreds of miles downwind, and landing people in hospitals. Here is a clear-eyed look at what crop residue burning actually does, and why it matters.

Nutrient loss and soil health
Greenhouse gas emissions
Air quality degradation
Health risks
The bigger picture

Nutrient loss and soil health

Crop residue – the stalks, straw, and stubble left after harvest – is not just waste material. It is a slow-release package of carbon, nitrogen, phosphorus, potassium, sulfur, and magnesium. When that material is burned instead of being returned to the soil, those nutrients are either volatilized into the atmosphere or locked into ash that washes away with rain.

Research published in Applied and Environmental Soil Science found that burning wheat crop residue caused soil organic matter to drop significantly – from 15.63 g/kg to 11.78 g/kg – alongside a sharp reduction in magnesium, a nutrient critical for plant enzyme activity. The study also documented that burning triggers a rapid initial release of CO₂ from disturbed microbial activity, accelerating the loss of organic carbon that took years to accumulate.

According to the University of Arkansas Division of Agriculture, burning crop residue leads to three primary losses: plant-essential nutrients leaving the field, a drop in soil organic carbon that reduces the soil’s ability to hold water, and the removal of the protective surface layer that guards against erosion. Soil organic matter is particularly important – every 1% increase allows the soil to hold an additional 20,000 gallons of water per six-inch depth. Burning eliminates that capacity.

The financial dimension of this nutrient loss is significant. Calculations by University of Arkansas soil scientists show that burning residue from a high-yielding rice or corn crop destroys roughly $275 worth of nutrients per acre – including nitrogen, phosphorus, potassium, and sulfur. Multiply that across the more than a million acres of rice planted annually in Arkansas alone, and the cost reaches into the hundreds of millions of dollars in lost soil fertility.

Long-term field studies from the Indo-Gangetic Plains confirm the pattern: plots where residue was retained or incorporated showed significantly higher available nitrogen, phosphorus, and potassium compared to burned plots. Prolonged burning – practiced for more than 15 years – results in measurable, lasting degradation of soil health and productivity.

Greenhouse gas emissions

Burning crop biomass sends a cocktail of greenhouse gases directly into the atmosphere. The main ones are carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). While CO₂ from burning renewable biomass is sometimes treated as carbon-neutral in policy frameworks, methane and nitrous oxide are not – they are respectively 25 and 298 times more potent than CO₂ as greenhouse gases and contribute directly to radiative forcing regardless of whether the biomass regrows.

Studies on rice-wheat systems show that burning releases roughly 70% CO₂, 7% carbon monoxide, about 2% nitrous oxide, and 0.66% methane by composition. All of these contribute to the greenhouse effect. A single 2-hectare farm study conducted over two years in Central India found that rice and wheat residue burning emitted over 27,000 kg of CO₂, 165 kg of CH₄, and 11 kg of N₂O – a combined global warming potential of more than 34,400 kg CO₂ equivalent.

At the national scale, the numbers are staggering. A satellite-based study tracking Indian crop burning from 2011 to 2020 found that greenhouse gas emissions from agricultural residue burning increased by approximately 75% over that decade, rising from around 19,340 Gg per year in 2011 to nearly 33,834 Gg per year by 2020. Punjab state alone accounted for burning on 27% of its total cultivated area in 2020.

India is not alone in this trend. According to the U.S. National Emissions Inventory, agricultural field burning in the United States produced approximately 67,310 tons of PM2.5 emissions in 2020, representing about 20% of total national PM2.5 emissions from all sources. The United States ranks third globally in agricultural burning greenhouse gas emissions, behind China and India.

Air quality degradation

Crop residue burning is one of the most concentrated short-term sources of particulate matter pollution that exists. The smoke it produces is dense with PM2.5 and PM10 – fine and coarse particles that linger in the atmosphere, travel hundreds of miles with wind, and settle over densely populated urban and rural areas alike.

India generates approximately 488 million tonnes of crop residue annually, of which around 24% is burned in fields. That burning releases 824 gigagrams of PM2.5, along with sulfur dioxide, nitrogen oxides, ammonia, volatile organic compounds, and polycyclic aromatic hydrocarbons (PAHs). The pollutants do not stay local – they travel downwind into major population centers.

The impact on cities is well-documented. Research published in the International Journal of Epidemiology found that when rice farmers in northwestern India burn their fields, PM2.5 concentrations in Delhi – located hundreds of kilometers downwind – spike to roughly 20 times above the World Health Organization’s safe air threshold. During the October-November burning season, crop residue burning can account for more than 50% of the PM2.5 measured during pollution episodes in the Delhi-NCR region.

The problem extends well beyond India. Across Southeast Asia, Sub-Saharan Africa, and South America, seasonal crop burning drives cities like Lahore, Dhaka, and Chiang Mai into the ranks of the world’s most polluted urban centers. In 2023, Thailand saw two million people seek medical attention linked to air pollution during the country’s agricultural burning season between December and April.

Beyond particulates, burning also releases precursor gases – nitrogen oxides and volatile organic compounds – that react with sunlight to form ground-level ozone. Ozone at ground level reduces photosynthesis, damages plant tissues, and compounds the air quality problem already created by the direct smoke emissions. The combined effect includes smog, haze, heat waves, and severe visibility reduction across broad regional corridors during burning seasons.

Health risks

The health consequences of crop residue burning fall hardest on the communities closest to the fires – and on children in particular. The particulate matter and toxic gases generated by burning penetrate deep into the lungs and enter the bloodstream, triggering a wide range of acute and chronic health conditions.

A year-long study that tracked lung function in children aged 10-13 and adults aged 20-35 in a village surrounded by agricultural fields in Punjab, India found that children’s forced vital capacity – a key measure of lung function – dropped from a mean of 98% in August to as low as 88% during October and November, when rice residue burning was at its peak. Critically, children’s lung function remained depressed throughout the study period, suggesting the damage does not fully reverse between burning seasons. Adults also showed decline during burn periods, but largely recovered afterward.

A separate epidemiological study covering 250,000 individuals found that people living in areas with intense crop burning face a three-fold higher risk of acute respiratory infection compared to those in areas without burning. Children were identified as particularly vulnerable. The same study estimated that eliminating crop burning in northern India alone could avert disability-adjusted life years valued at over US$1.5 billion across a five-year period.

The toll at national scale is severe. A study published in Nature Communications estimated that agricultural residue burning caused between 44,000 and 98,000 premature deaths in India annually from 2003 to 2019, with Punjab, Haryana, and Uttar Pradesh together accounting for 67-90% of that burden.

Beyond respiratory disease, research reviewing health outcomes across multiple domains links crop residue burning exposure to cardiovascular disease, autoimmune disorders, neurological impairments, and increased microbiological risks. Surveys of farming households in Pakistan found that the most commonly reported symptoms during burning season were coughing (45%), eye irritation (33%), headache (31%), nausea (29%), skin irritation (23%), and respiratory allergies (22%), with more severe cases involving asthma, bronchitis, and COPD. Prolonged exposure to particulate matter from crop burning is also associated with a measurable reduction in life expectancy – one estimate suggests Delhi residents lose up to 6.4 years of life due to high pollution levels, much of which is driven by seasonal burning.

The bigger picture

What makes crop residue burning particularly challenging is that it damages multiple systems at once – soil, atmosphere, air quality, and human health – while being driven by real pressures that farmers face: tight turnaround times between cropping seasons, limited access to equipment, and a lack of affordable alternatives. As mechanized harvesting has expanded in cereal-based farming systems, it leaves behind more residue than farmers can manage without burning. The practice is rational in the short term and destructive in the long term.

Alternatives do exist – in-situ incorporation using happy seeders, composting, mulching, biochar production, and use of residue as livestock feed – but they require investment, knowledge transfer, and in many cases, direct policy support. Evidence from Pakistan and India shows that when farmers are given accurate information and practical tools, many are willing to shift away from burning. The benefits – healthier soil, cleaner air, reduced healthcare costs, and a more stable climate – far exceed the short-term convenience of setting the field on fire.

What do you think? Given that crop residue burning is often driven by economic necessity rather than carelessness, who bears the greater responsibility for change – individual farmers, governments, or agricultural technology developers? And as regions continue to intensify crop production to meet food demand, how should the environmental and public health costs of field burning be factored into agricultural policy?

References

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Table of Contents

Nutrient loss and soil health 🔗

Greenhouse gas emissions 🔗

Air quality degradation 🔗

Health risks 🔗

The bigger picture 🔗

References

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Environmental Issues

Nutrient loss and soil health

Greenhouse gas emissions

Air quality degradation

Health risks

The bigger picture