Paddy straw is a central field-based residue that is produced in large amounts in Asia. In reality, it could theoretically produce 187 gallons of bioethanol from the total area if the technology were available. However, an increasing proportion of this paddy straw encounters field burning, and this improper management results in high fuel prices and air pollution. For the past 25 years, conservation farming has continued to evolve. There is now less burning and, therefore, less soil cultivation and increased crop stubble retention. This trend is growing because of the need to improve water use and protect soils from erosion. As climate change is a threat to development, there is a growing interest in alternative uses of agricultural remnants.
What is stubble burning?
Crop stubble is the straw and crown of plants left on the field after harvest. Stubble consists straw and chaff discharged from the harvester. It is also known as ‘residue’ or ‘trash’. Managing this agricultural waste is one of the complex tasks that farmers must be concerned with. Usually, farmers burn stubble to manage weeds and diseases and reduce biomass to make sowing better. This is no longer a good option, as many other alternatives manage the residuals.
There are primarily two types of residues from rice cultivation that have potential in terms of energy—straw and husk. Although the technology of using rice husk is thoroughgoing in many Asian countries, paddy straw, as of now, is rarely using as a source of renewable energy. One of the principal reasons for the major use of husk is its easy procurement, i.e., it is possible at the rice mills. Collecting paddy straw is tedious, and its availability is tedious during harvest time. The collection logistics improve through baling, but the fundamental equipment is expensive and buying it is uneconomical for farmers. So technologies should develop for the efficient use of a straw to commit for the high costs involved in straw collection.
Retaining stubble than burning or cultivating, protects the soil from erosion. It also preserves soil moisture and organic matter to retain crop production. This is mainly beneficial in dry areas or dry seasons. Stubble impact many things, including the passage of equipment, penetration, soil temperature, herbicide interactions, frost severity, pests, weeds and other problems. Burning is often used as a last way to manage heavy agricultural residuals. Stubble burning contributes to global warming to a great extent. About 39 million tonnes of paddy straw are burning yearly. In The Indian state of Punjab, rice farms burn about 7 to 8 million tons of leftover plant debris. Similarly, the total national annual emission for CO2 from crop residue burning is more than 64 times the total CO2 pollution emission in Delhi.
Why do farmers choose stubble burning?
Burning paddy straw residue has risen remarkably over the past twenty years. Despite the benefits of keeping the stubble, most of the farmers opt for heavy stubble burning for the following reasons:
- Ease of sowing and better establishment of tiny seeds like canola.
- To make the area most inappropriate for many types of pests.
- To manage certain weeds, mainly herbicide-resistant weed populations.
- Burning is the cheapest and easy way to remove stubble and control weeds.
- Reduced reliance on agricultural chemicals.
- Provides better weed control caused due to a more even spreading of herbicides and effective incorporation of pre-emergent herbicides.
- Less nitrogen tie-up -Nitrogen tie-up in cropping soils is only a temporary constraint as the immobilised N will be released through microbial turnover, mostly later in the crop season in spring.
- To some extent, it results in less frost damage to crops.
- By completely removing the stubble, only less inoculum is required for certain crop diseases.
Harmful effects of burning
- Atmospheric pollution and climatic changes:
Open stubble burning emits many toxic pollutants into the atmosphere, which contain harmful gases like methane, carbon monoxide etc. These gases contribute a lot to the formation of smog. Stubble burning emits delicate particulate matter at high levels, which concerns people’s health. These particles can get trapped inside the lungs, ultimately leading to lung cancer. Pollution from stubble burning significantly reduced lung function and was particularly harmful to people in the surrounding area.
- Effects on soil fertility and agricultural production:
Stubble burning affects soil fertility through the destruction of nutrients present in the soil.t also raises the soil temperature to about 42 °C, thus displacing or killing the essential microorganisms in the soil at a depth of about 2.5 cm. Thus successive fire destroys the soil’s fertility, resulting in the reduction of crop yields over time, and therefore growers have to rely on costly fertilisers.
- Effects on human health and mortality rates:
Many studies have established the vital role of air pollution in the rising health problems, especially among children, pregnant women, elderly persons, and people with pre-existing health issues. This hazardous chemical produced as a result of burning causes problems for skin and eyes irritation, severe neurological, cardiovascular, and respiratory diseases etc. Moreover, the first and primary target of toxic substances inhaled through the air causes respiratory system disorders, cancer, or even death in extreme cases. Continuous exposure to particulate emissions may lead to an elevated cardiovascular mortality rate.
Alternatives to burning heavy stubble
There are many valuable ways to manage stubble rather than burning it and causing pollution. Some of them are :
- Growers should focus on cutting heavy stubble and using it after harvest. This helps to shorten stubble, retain soil moisture and accelerate decomposition.
- Inter-row sowing allows stubble to be retained when crop rows are more than 22 centimetres wide.
- Growers may need to review stubble management decisions each year.
- Strategic removal of stubble-it is possible to lower stubble loads if they are likely to make problems with sowing, establishment or weed management. Legume and oilseed crops produce reduce stubble loads. Their inclusion in the rotation may help to manage the risk of stubble burning.
- Grazing-Small mobs of sheep in large paddocks often only reduce stubble loads in parts of the paddock.
- Bailing- It is possible to remove stubbles profitably after harvest by baling straw. Baled straw has been used in animal bedding, mushroom compost and livestock feed for some years. It has other potential uses, such as for bioenergy.
Since the pollution from stubble burning has become a concern, Khaitan bioenergy has found a way to extract ethanol from it, which is a valuable fuel. Thus proper stubble management is economically beneficial to farmers and can protect the environment from severe pollution.
Biofuel production and energy generation
Recently much progress has done in the usage of stubble for biofuel production. This applies to managing agricultural stubble, which promotes cleaner air and a greener environment by preventing the release of toxic emissions by burning and indirectly reducing the use of fossil fuel-based energy. India ultimately depends on imports for automobile fuel, spending massive amounts of money for obtaining and transporting into the country. A shift from fossil fuel energy to biofuel produced from agricultural stubble is a feasible alternative. Biofuels have recently been gaining global interest due to their lower carbon footprint than fossil fuels.
Most farmers in North India are unaware of these prolific alternatives and, therefore, consider burning the best option. This necessitates extensive awareness programs to enlighten the growers about the availability of economically feasible options and the combined effects of stubble burning.
In short, despite the federal and state government’s strict policies and legislation to ban the burning practices, the activity continues in many parts of northern India, especially in Punjab, Haryana and Uttar Pradesh. Nationalistic compliance with these strategies requires effective follow-up with timely and continuous tracking everywhere. The government should compel the pulp and paper production, bioenergy and power industries to use the crop stubble as a proportion of their raw materials. This will motivate the farmers as selling the stubble will generate additional income. So an immense awareness program is necessary to notify the farmers of the environmental and economic benefits of using alternative approaches for managing the crop stubble.