Rice is our staple food. It is the lifeline of our farmers. In Bangladesh, food security essentially means rice security. Because our food culture is largely dependent on rice, nearly 75 percent of the country's cultivated land is used for rice farming. However, in this rice-dependent country, several negative narratives are widely circulated. For example, it is often claimed that rice fields emit greenhouse gases, that Bangladeshi rice contains arsenic, that rice cultivation wastes groundwater, that eating rice causes diabetes, or that rice consumption leads to obesity. These misconceptions have no solid scientific basis.Among these, the most widely discussed issue globally is that rice fields emit greenhouse gases. This statement is only half true. The complete truth is that rice plants absorb nearly an equal amount of greenhouse gases as they emit. Let us examine the scientific explanation and analysis behind this.
From rice fields, greenhouse gases such as methane (CH?), carbon dioxide (CO?), and nitrous oxide (N?O) are emitted. At the same time, rice plants absorb these gases in the form of carbon dioxide to carry out their physiological processes. However, in negative campaigns, only the emission aspect is strategically highlighted, while the fact that rice plants absorb a significant amountoften comparable to the emissionsis rarely mentioned. Today's write-up focuses on the balance between these emissions and absorptions of GHGs.
The Soil Science Division of the Bangladesh Rice Research Institute (BRRI) has been conducting research on this issue since 2013. Studies show that producing 1 kg of rice results in the emission of about 666 grams of carbon dioxide, 53 grams of methane, and 0.5 grams of nitrous oxide from rice fields. On the other hand, to produce 1 kg of rice, the rice plant absorbs about 2,200 grams of carbon dioxide through the process of photosynthesis.In addition, methane reacts with water vapor in the atmosphere and is converted into carbon dioxide and hydrogen gas. These gases are then absorbed by rice and other plants through photosynthesis. Similarly, nitrous oxide reacts with atmospheric water vapor to produce ammonium and hydrogen gases. Ammonium, brought to the soil through rainfall, undergoes various organic transformations in the soil and eventually becomes nutrients that plants can use.In this process, oxygen from the atmosphere travels through the rice plant's aerenchyma channels to the roots and into the soil. There, it reacts with methane and, with the help of methanotrophic bacteria, produces carbon dioxide. This carbon dioxide is absorbed by the plant, and the process helps reduce methane emissions into the atmosphere.
Research also shows that rice plants themselves contribute only about 5-10 percent to methane production, while the remaining 90-95 percent originates from the soil. In waterlogged fields, labile organic carbon and methanogenic bacteria generate methane. Therefore, compared to rice cultivation, fallow land and landfills can sometimes be more responsible for methane emissions.
In Bangladesh, more than 50 million tons of paddy are produced annually across the three major seasons-Aus, Aman, and Boro. Based on this production level, the total emissions associated with 50 million tons of rice production are estimated at about 33.3 million tons of carbon dioxide, 2.65 million tons of methane, and 0.025 million tons of nitrous oxide. According to the Global Warming Potential (GWP) formula, the combined carbon dioxide-equivalent emissions of these three greenhouse gases amount to approximately 112.2 million tons.
On the other hand, through the process of photosynthesis, rice plants absorb about 2,200 grams of carbon dioxide to produce 1 kilogram of rice. Therefore, in producing a total of 50 million tons of rice, approximately 110 million tons of carbon dioxide are absorbed from the atmosphere. According to the earlier calculations, the amount of greenhouse gases absorbed through rice cultivation (about 110 million tons) and the amount emitted (around 112.2 million tons) are nearly equal, although emissions are slightly higher.This indicates that rice cultivation not only emits greenhouse gases into the atmosphere but also absorbs them. At the same time, it contributes to improving atmospheric conditions.
In almost all countries of the South Asian region, activities such as rice cultivation, wetland filling, and coal extraction are common. Some countries, including China and India, cultivate far more rice than Bangladesh. Although Bangladesh possesses several coal deposits, currently only one coal mine operates on a large scale. In contrast, neighboring India has hundreds of active coal mines, while China has more than a thousand.These mines are considered major sources of methane emissions. Therefore, compared with Bangladesh, larger rice-producing countries bear a greater share of responsibility for greenhouse gas emissions. In reality, developed countrieslargely responsible for greenhouse gas emissions-often attempt to blame developing nations for climate change. This issue is no exception.
Bangladeshi scientists have also noted that Dhaka is the country's only major megacity, and the per-capita waste generation there is significantly lower(about 0.61 kg per person per day) than that of many large cities in neighboring countries.What requires the greatest attention is how greenhouse gas emissions can be reduced while maintaining agricultural productivity. In this context, the Bangladesh Rice Research Institute is working on future strategies and has already taken several initiatives to implement them.
The world is now approaching the Fourth Industrial Revolution, and Bangladesh has already begun integrating with this transformation. Its implementation is expected to significantly reduce greenhouse gas emissions. Precision agriculture practices will become more widespread, enabling efficient use of resources. Through genome editing, it will be possible to develop rice varieties with enhanced greenhouse gas absorption capacity. The application of nanotechnology may also help reduce emissions. Artificial intelligence could enable technologies such as artificial rainfall, while desalination processes for reducing salinity in water may become easier and more efficient. The use of solar energy is also expected to increase.Therefore, rather than becoming discouraged, it is wiser to remain optimistic and work toward constructive solutions.
The writer is an Senior Communication Officer, Bangladesh Rice Research Institute, BRRI
