How to control air pollution from stubble burning

This article originally appeared in Times of India

This is a straightforward article to discuss the real issues concerning stubble burning, including its contribution to pollution in Delhi-NCR, and why the solutions promoted by the government are not working.

Let’s start with the contribution of stubble burning to air pollution in Delhi-NCR. While we can bicker over the numbers, stubble burning is a short duration, highly polluting activity that significantly impacts air quality in October and November. The equation is simple: The 15-20 million tonnes of paddy stubble burnt in Punjab, Haryana, and western Uttar Pradesh, emit PM2.5 that is 4-5 times the annual PM2.5 emissions from all vehicles plying on Delhi roads. Let me repeat: PM2.5 emitted from stubble burning in just 60 days is 4-5 times what all Delhi vehicles emit in the entire year.

The intensity of emissions from stubble burning, therefore, is so high that even if a small fraction of these reaches Delhi, it would cause the city’s air quality to deteriorate significantly. This is precisely what happens during the stubble burning season. Wind coming from the northwest picks up pollutants from Punjab and Haryana and brings them to Delhi, worsening its already polluted air.

The next question is, why do farmers burn paddy stubble? First of all, not all farmers burn it; only about 25% of the paddy residues are burnt in Haryana, and this number goes up to 50-60% in Punjab. So, why do some farmers put their fields to flames while others don’t? There are three primary factors, apart from a few minor ones, that are driving this practice.

The most important factor is the technology used for harvesting. Farmers using Combine Harvester (called Combine) are most likely to burn the stubble, whereas those practising manual harvesting don’t. Combines cut the grainy part of the paddy plant (called spike) and leave about 30 cm of stem intact in the field. The farmer either has to manually cut the stem, use some machine, practice in-situ management, or burn it. Among these, burning is the easiest and most cost effective option.

The next factor is the use of the straw. Farmers who are unable to use or sell straw are burning it. In Punjab and Haryana, basmati paddy is mostly harvested manually because its straw is highly valued as animal fodder. The incidence of burning in basmati fields is, therefore, very low.

On the other hand, non-basmati straw is not used as animal fodder and hence is burnt. But there is a growing demand for non-basmati fodder in Rajasthan and Gujarat, and industries are also buying it for energy and other uses. Farmers who can sell their non-basmati straw do not practise stubble burning. Lastly, small farmers and tenant farmers are more likely to burn the stubble than big farmers, as they have fewer resources and risk appetite for using alternative technologies.

Now, let’s come to solutions promoted by the government. It has adopted a carrot and stick approach. On the one hand, it has banned burning and is imposing fines on farmers; on the other, it provides 50-80% capital subsidy to acquire farm machinery to adopt in-situ crop residue management. Unfortunately, neither is working.

It is vital to understand that the farm machinery the government is subsidising is not primarily designed to stop stubble burning. These machines are meant for zero tillage farming, in which stubble can be kept on the field and recycled in the soil. The zero tillage method has significant ecological benefits, including improvements in soil quality and lower water consumption; reduction in stubble burning is a co-benefit.

But zero tillage farming has two problems. First, it is an entirely new method of agriculture for Indian farmers. They have practised tillage agriculture for centuries, and therefore, moving them to zero tillage will not happen quickly. Second, it has a higher upfront cost. Despite subsidies, farmers incur an extra charge of about Rs 2,500 per acre to use these machines, which most can’t afford.

What, therefore, emerges from the above is that the use of Combines, weak market linkages for non-basmati stubbles and promotion of expensive technologies that require a long time for adoption, are sustaining the practice of stubble burning. What we need is a solution that is scientific, affordable, and culturally adaptable.

The easiest and affordable solution is to modify the Combine Harvester itself. We can redesign the Combine to cut the paddy straw from the plant’s base to remove the stem. The straw can either be sold or used as mulch in zero tillage agriculture. We can even incorporate a baling machine to the Combine to bale the straw, which can then be easily transported and sold.

The good news is that some newer versions of Combine already incorporate these features. I am not going to name companies, but I have seen foreign companies selling, in Haryana, precisely the kind of Combine I have explained above. The question is why Indian companies are not modifying their Combines and why the government is overlooking this simplest of solutions?

Ockham’s razor is a problem solving principle which states that the simplest solution is more likely to be correct than complex ones. This certainly is the case with stubble burning. By promoting complex solutions instead of a simpler one, we have botched up the stubble burning problem.