The vicious cycle of rice straw burning in Vietnam

Vietnam is the fourth-largest producer of rice in the world. Between 2013 and 2015 alone the average annual production of rice was 44.7 million tons. Recent years, however, have shown an improving trend in rice straw management but the pollution caused by the burning of rice straw remains much beyond the safe limits in Vietnam. 

What is the problem?

Rice is one of the staple crops in the world and the most vital food resource produced in Vietnam. Not only that, as the current population grows so too will the need for food production, rice included. One of the most critical factors in the impact of rice production on climate change is the burning of the leftover rice straw. In addition to climate consequences, it also has catastrophic effects on human health, as it is vastly responsible for the suffocating pollution fogs observed in Southeast Asia’s big cities in recent years. Moreover, the rice production, the rice straw burning and the negative impact on climate change have in turn bad consequences on the rice production yield, which makes it urgent to stop this vicious cycle.

In this post, some of the main consequences of rice straw burning on climate change and human health, particularly in Vietnam, will be addressed. Let’s find out more what’s this vicious cycle.

What is the Vicious Cycle and why does it matter?

Rice is one of the most important food items produced in Asia, where about 90% of the world’s rice is produced and essentially exported to feed the worldwide population. However, it is also a major contributor to climate change. Greenhouse gas (GHG) emissions are released during its cultivation, and more heavily during the disposal of the leftover waste. Rice production and straw disposal are part of a vicious circle responsible for negatively impacting Earth’s climate and food nutrition quality.

Here are a few more examples, proving that the vicious cycle of rice straw requires our attention and effort:

• To produce rice, high concentrations of nitrogen fertilizers are usually used by the farmers. This has a negative impact on the ecosystems.

• To produce rice, large amounts of fresh water is needed. Only 3% of the water on Earth is freshwater, and two-thirds is unavailable for our use.

• After the harvest, most of the rice straw is burnt in open fields, which leads to an enormous release of those GHGs in the atmosphere.

• With a rising population, more rice is required, more production is needed. Consequently, more water is needed, more fertilizers are released to the sand and water (i.e. rivers), and more straw is burnt.

• The quality of rice production is being severely impacted by climate change through these previous aspects. For example, the upper basin of the Ganges River is already observing a downfall in its production.

Climate change impacting rice production

The International Food Policy Research Institute (IFPRI) report on Climate Change: Impact on Agriculture and Costs of Adaptation forecasts that by 2050 rice prices will increase between 32 to 37% as a result of climate change. They also show that rice productivity will reduce by 14% in South Asia, 10% in East Asia and the Pacific, and 15% in Sub-Saharan Africa.

In Vietnam, more than half of rice farming is done along the coastal river deltas, particularly in the Mekong River delta, which is to become highly vulnerable due to sea levels rising. This problem is intensified as a rise in sea level also brings an increase in salt content in the soil which is not well tolerated by the rice plant.

Furthermore, climate change can also impact rice production levels through rainfall patterns fluctuations which can be very detrimental for crop yield, whether it is flooding or drought ^[1].

How can we solve this problem in Vietnam?

One of the main contributors to rice production’s impact on climate change is also one of the main levers that can be acted upon to limit this impact. In Vietnam particularly there is a lot of room for improvement as it is estimated to be the country that burns the most rice straw relative to its rice production. 

^{Rice Straw burning comparison among the leading global producers}

The open burning of rice straw in the fields is not only a vast source of pollution but also an enormous waste of organic material. Indeed, rice straw waste can be turned into many fruitful alternatives, as described below.

• Rice straw can be incorporated into the soil to be used as a natural fertiliser. This decreases the need for artificial fertilizers, and thus decreases the carbon footprint of rice cultivation. Studies have shown the rice yield in the years following straw incorporation in the soil is significantly increased, as well as the soil quality is improved ^[2]. However, it is labour-intensive which in turn makes the land preparation expensive compared to the common practice of open-field burning.

• Rice straw can be used as ruminant feed. Despite a quite low nutritional value, with low protein value, and poor digestibility (mainly due to lignin-cellulose linkages in the plant), it is still used in Africa and India. It is possible to break down the structure of the plant with several treatments that improve its digestibility for large grazing animals.

• Rice straw can be collected for mulching, shown to be highly beneficial for controlling weed growth by increasing water retention in the soil, thus decreasing the overall need for chemical weedicides and excessive freshwater. Mulching also has a positive impact on the protection of the plant from very cold weather during winter.

• Rice straw can be used as a substrate for mushroom growing as it is considered a very good media for this purpose.

• Rice straw has a huge potential to be used for biotechnological applications, such as the generation of electricity, production of biogas, biofuels, bioplastics, pharmaceuticals, food supplements, etc.

In India and China for almost 20 years, rice straw combustion has been used to produce greener electricity. One set back however is large quantities of straw are required for the production to be economically viable, which can become problematic when crops are not very abundant. Logistically, these powerplants would need to be located directly in the area of rice production in order to limit transportation costs. Biogas production is another alternative to burning rice straw waste, as it can be used as a renewable energy source through anaerobic digestion of the rice straw. By breaking down the structure of the plant through chopping, fermentation and digestion, biogases such as methane and carbon dioxide can be released, which can, in turn, be used for energy production. This method is not as well developed as others but represents a sustainable alternative for rice straw waste as well as other types of agricultural waste.

In Conclusion

The vicious cycle of rice straw waste burning represents a non-negligible danger for the environment, as well as for human health. The constant increase in world population is a key aspect of the ever-growing demand in food production that is essential to be met. However, the costs to the environment are also of paramount importance, as they will mean the rice production will not be maintained. Therefore, efforts towards a more sustainable production have to go through finding alternatives to polluting methods currently in place, such as the rice straw burning. A lot of possibilities are already being developed but there is an urgent need for governments to step up and encourage these alternatives, via providing more information to farmers about the benefits of such alternatives, but also via financing their development, particularly in Vietnam where a lot of progress can be made. There are already some initiatives in India, which could most definitely be applied to Vietnam, such as the Indian government financing machinery, leading the Punjab state to a zero stubble burning area.

The future belongs here, rice straw is a very valuable feedstock that can be used to produce everything we need in our daily life without compromising the climate of the planet.  The utilization of biorefinery is one way to convert rice straw to high valuable products. This is elucidated in more detail in our other articles: Biorefineries;Bioethanol, a carbon dioxide neutral energy source; Malic acid is part of your daily life

¹ Singh, G., Gupta, M. K., Chaurasiya, S., Sharma, V. S. & Pimenov, D. Y. Rice straw burning: a review on its global prevalence and the sustainable alternatives for its effective mitigation. Environ. Sci. Pollut. Res. 28, 32125–32155 (2021).