Stubble burning: A lose-lose situation with no silver lining

India is the third-largest emitter of greenhouse gases globally, releasing 2,830 Mt CO2 annually. One major factor driving this issue is stubble burning a common practice where farmers set fire to crop residue to clear their fields for the next planting season quickly. This method has been a major cause of air pollution in the National Capital Region (NCR) and the Indo-Gangetic plains, especially before winter.

The stubble burning season has officially begun, with satellite data showing 124 farm fires in Punjab, Haryana, Madhya Pradesh, and Uttar Pradesh between September 15 and 23. This marks a notable increase from just 25 cases in 2023, indicating a fluctuating trend compared to previous years, with 132 fires recorded in 2022 and only 16 in 2021. So far, 320 fires have been reported this year, down from 620 and 1,935 in 2021 and 2020, respectively.

Data from the Indian Agricultural Research Institute shows that Punjab recorded the highest number of farm fires, totaling 69. Haryana followed with 46 fires, while Madhya Pradesh had six and Uttar Pradesh reported three. Notably, 51 of the fires in Punjab occurred in Amritsar, and significant activity was seen in Karnal, Haryana, with 24 fires, and Kurukshetra with eight fires. 

Due to this Air Quality Index (AQI) is declining day by day, particularly in regions like Delhi and the NCR. Every year, extreme fog during winter is exacerbated by stubble burning in nearby states, where farmers burn crop residue to clear fields for the next planting season. This practice significantly increases air pollution, contributing to the worsening air quality and health issues in the region.

In some cases, stubble burning has become a necessity. For example, late rains in September in Punjab and Haryana delayed paddy harvesting by a week, resulting in a limited window for sowing the next wheat crop, making stubble burning the quickest method to clear the fields before planting.

Fire crackers Vs stubble burning

A study published in June 2022, led by researchers from IIT-Delhi, revealed stubble burning poses greater long-term harm than firecrackers with alarming insights into the apportionment and speciation of PM 2.5 caused by firecrackers and stubble burning throughout 2021. The findings highlight the significant and harmful impacts of stubble burning, particularly around Delhi, where it contributes approximately 20 to 30 micrograms of PM 2.5 per cubic meter.

However, this effect persists for about a month, occurring four times a year, highlighting the recurring threat to air quality. The composition of PM 2.5 resulting from stubble burning is primarily made up of black carbon, which poses serious long-term environmental risks. Black carbon is known for its detrimental effects on human health, contributing to respiratory issues and cardiovascular diseases. 

Furthermore, the accumulation of black carbon in the environment can lead to soil degradation and negatively impact agricultural productivity. In contrast, firecrackers produce a more immediate yet shorter-lived spike in air pollution, contributing up to 600 micrograms of PM 2.5 per cubic meter.

While this concentration is significantly higher, it typically dissipates within 36 hours, dropping to around 20 micrograms per cubic meter after a month. However, the composition of pollutants from firecrackers is particularly concerning, as it is primarily made up of heavy metals, which are toxic to both humans and the environment. 

Firecrackers cause a short-term air quality crisis, but stubble burning poses a longer-lasting threat due to harmful black carbon, impacting both health and the environment.

Effects of stubble burning 

Stubble burning has several harmful and negative impacts. It leads to the loss of valuable nutrients such as nitrogen, sulfur, phosphorus, organic carbon, and potassium, which could otherwise be used to create organic manure, ultimately increasing dependence on chemical fertilizers.

The burning process also destroys vital soil nutrients, reducing soil fertility and harming beneficial microorganisms that are essential for a healthy ecosystem. This disruption can result in an increase in pests and crop diseases, complicating management efforts. Furthermore, while burning may reduce some disease levels, it only offers partial control, as some disease-carrying stubble may remain, undermining agricultural sustainability and soil health.

Also, it generates heat that depletes soil moisture and beneficial microbes. Stubble burning is a major contributor to air pollution in North India, worsening air quality with harmful emissions like carbon monoxide, methane, and carcinogenic pollutants, contributing to winter smog in cities like Delhi.

Although burning stubble can help manage diseases like crown rot and take-all, it doesn’t eliminate below-ground inoculum and may even worsen crown rot due to drier soils later in the season. In contrast, retaining stubble can support disease management, as seen with reduced infections in crops like chickpea and lupin when sown into mulched stubble. 

Government initiatives to reduce stubble burning 

For years, the central government and affected states have worked together to find solutions to address stubble burning. One significant attempt involved providing one-time cash compensation to farmers, as directed by the Supreme Court. However, this initiative faced challenges due to inadequate budget support from both state and central governments.

Innovative solutions like the bio-decomposer developed by the Indian Agricultural Research Institute (IARI) were promoted as potential game changers. However, field trials in Punjab showed that the bio-decomposer took 25 to 30 days to break down stubble, creating a narrow window between paddy harvesting and wheat sowing and leading to farmers’ reluctance to adopt the technology widely. 

Recently, the Delhi government has introduced a free bio-decomposer as an alternative to stubble burning in the national capital. 

Research from Punjab Agriculture University indicated that the stubble decomposition period could exceed a month, resulting in limited use of the bio-decomposer, which has only been applied to a small percentage of Punjab’s total paddy area. In Haryana, while farmers remain skeptical, there is a broader use of the bio-decomposer. The director of the Haryana Agriculture  Department reported that the solution has been applied to a significant area, and satellite data has shown no fires in locations where the decomposer was utilised.

Alternatives to combat stubble 

Several effective alternatives can be implemented to minimise Stubble burning which includes establishing paddy straw-based power plants that can reduce burning while creating job opportunities and generating renewable energy. Composting crop residues into enriched organic manure not only reduces waste but also enhances soil health.

Moreover, scientific research into industrial applications, such as yeast and protein extraction from crop residues, can open new markets. Incorporating crop residues back into the soil improves moisture retention and boosts microbial activity, fostering better plant growth.

Other practices like mulching, biochar production, cover cropping, and agroforestry further contribute to soil health and sustainability. Raising awareness and providing training for farmers on these practices, along with government incentives, can encourage the transition away from stubble burning, promoting a more sustainable agricultural system.