The recent severe air pollution crisis in the NCR-Delhi region is reportedly linked to the change in the timing of stubble burnings conducted by farmers in the neighbouring states of Punjab and Haryana. This timing adjustment has been influenced by the Punjab Preservation of Subsoil Water Act (PPSW), 2009, causing a considerable environmental impact.
Historical Burning Practices Prior to the PPSW Act, 2009
In the past, particularly before the introduction of the PPSW Act in 2009, Punjab farmers began sowing paddy nurseries from mid-to-late April and transplanting the seedlings from mid-May to late-May to prevent weed growth. However, this method posed a considerable drawback, leading to massive groundwater depletion due to constant irrigation during peak summer months.
The result was that paddy, including 155-day varieties such as Pusa-44, got harvested by early October, and the burning of the stubble concluded around mid-October. This gap between the stubble burning period and the onset of winter in Northern India prevented the occurrence of an air pollution crisis in the region.
The Influence of the PPSW Act, 2009
To curb the groundwater crisis during summer, the PPSW Act was enforced. The Act prohibited nursery sowing and transplanting of paddy before May 15 and June 15, respectively. Consequently, a significant segment of the crop’s water requirement could be satisfied by monsoon rains, reducing water loss due to evaporation after mid-June. However, late transplantation left farmers with little preparation time for the next crop, leading to a rise in stubble burning incidents.
| Stubble Burning Practices | Before PPSW Act, 2009 | After PPSW Act, 2009 |
|---|---|---|
| Paddy Nursery Sowing | Mid-to-late April | After May 15 |
| Transplanting of Seedlings | Mid-May to late-May | After June 15 |
| Stubble Burning Period | Ends Mid October | Coincides winter onset |
Benefits and Impacts of the PPSW Act, 2009
Despite causing an increase in stubble burnings, the PPSW Act has its positives. The delayed paddy transplantation has been instrumental in preserving approximately 1,000 billion litres of water – equivalent to the total water consumption of Ludhiana, an industrial town, for a period of two years.
However, the implementation of the PPSW Act also resulted in the stubble burning period overlapping with the onset of winter in Northern India. At this time, wind movement is typically slow and moisture levels in the lower atmosphere are high, creating a layer that accumulates particulate matter and gases from burnt stubble, vehicles, and industries – rather than allowing them to disperse. Coupled with the regional wind patterns, this scenario contributes to ‘air locking’ at many locations.
The PPSW Act may have succeeded in arresting the rapid decline in groundwater levels, however, it has unintentionally exacerbated the air pollution crisis in the region, causing a significant deterioration in the Air Quality Index (AQI) in the National Capital Region.