Rice is staple food of nearly 50 percent of the world's total population, i.e. 4 billion, mainly in Asian and African countries. In both continents, rice is produced by small farmers on small areas of land. Population of rice producing countries is growing at a rate of 1.5 percent annually. Resulting, current growth rate of rice production is not sufficient to feed them; Therefore, to meet growing demand, annual rice production needs to increase by two million tons. More than 90 percent of rice is produced and consumed in Asia. In Bangladesh, 170 million people depend on rice as their staple food.
In last three decades, world's food production has been greatly reduced due to drastic climate changes. In the meantime, various research institutes, United Nations, and FAO have said that food production must be increased to keep pace with the world's hostile climate as well as population growth. FAO predicts that by 2050, world will have 8.9 billion people. In future, to meet food demand of this world population, current rice production will have to increase from 520.9 million tons to 584 million tons in 2050.
In many Asian countries, rice yields have doubled within 20 years of the “Green Revolution” results of rapid expansion of improved varieties, increased cropping intensities and use of intensive inputs. During 1970s and 1980s, global rice production grew at a rate of 2.3–2.5 percent per year. The growth rate dropped to 1.5 percent in 1990s and further declined in first decade of the 21st century, mainly due to climate change, land degradation and fertility decline.
A study of top 20 rice-producing countries found that Cambodia is the largest emitter of methane gas due to rice cultivation. Thailand is second and Bangladesh is eighth position. Highest per capita greenhouse gas (GHG) emissions were recorded in Thailand at 1595.24 kg of CO2, followed by Cambodia at 1517.21 kg and Bangladesh at 706.72 kg. In terms of total GHG emissions for rice cultivation, Bangladesh ranks 6th among top 20 rice producing countries with an amount of 9,903.03 kg per hectare.
GHG emissions per kg rice production are 5.87 kg in China, 3.91 kg in Thailand and 3.44 kg in India. According to BBS, rice production in 2023 Aman season was 15 million tons, about 3.31 million tons in Aus and 20 million tons in boro. Total production of paddy in the country in 2023 is about 57 million tons. GHG in Bangladesh to produce 1 kg of paddy; CO2 emissions are 2.21 and 1.70 kg in dry and wet seasons respectively. As such, GHG in boro rice cultivation in the country in 2023; CO2 emissions were 68.51 million tons and Aus and Aman combined emissions were 44.2 million tons.
Although chemical urea fertilizers play an important role in increasing crop yields in the global agro-food system, they are not at all environmentally sustainable. According to a 2018 study, urea is responsible for 1.13 giga tons of CO2 emissions worldwide, which is 10.6 percent of global agricultural emissions and 2.10 percent of global GHG emissions. 38.8 percent of these GHG emissions of urea fertilizer were due to production, 58.6 percent for field use and remaining 2.6 percent due to transportation. In future, reducing the tendency of temperature increase due to global climate change and reducing environmental pollution due to urea fertilizer in crop production is a big challenge. Of course, the increasing GHG emissions from agriculture must be pulled to maintain sufficient food production systems for humans by combining climate-resilient technologies to reduce global warming. For this, efficiency of urea fertilizer should be increased by 70 percent by 2100.
Total annual requirement of urea fertilizer in Bangladesh is 3.4 million tons of which 80 percent i.e. 2.72 million tons is used only for paddy cultivation. Also, a total of 1.6 million tons of DAP fertilizer is used in paddy cultivation, of which urea is 18 percent i.e. 0.29 million tons. Most of farmers in Bangladesh apply urea fertilizer by split it on paddy land with only 30-35 percent uptake and 65-70 percent is wasted in various ways to the environment. In other words, total wastage of urea fertilizer in the country is about 1.65 million tons in paddy cultivation alone, with an international market value of Tk 1.59 million.
Since 1930, research has been going on in different countries of the world to prevent wastage of urea fertilizer and to increase efficiency. In continuation of that, BRRI, BARI, BINA conducted research on preventing wastage of urea fertilizer in the 1980s and successfully developed Urea Super Granule (USG) technology for urea deep placement. It can reduce wastage of urea fertilizer and save about 40% of urea. As fertilizer efficiency increases, rice yield also increases up to 25-50%. USG with a weight of 2.7 gms used in boro rice at 7-15 days after transplanting 7-10 cm depth of every four hills and in case of aman similarly 1.8 gm is used. It requires 170-240 kg of USG per hectare in boro rice (due to variation in transplanting distance) and 115-150 kg in aman.
USG helps farmers reduce production costs as well as increase yields. After 7-15 days of transplanting rice seedlings, if the USG is applied once, there is no need to use urea fertilizer until the rice is harvested, and plants do not have urea starvation. As USG is buried under soil, weeds cannot take up fertilizer. As a result, number of weeds is greatly reduced which helps to reduce cost of weeding. But if prilled urea is broadcasted, weeds get a chance to take up fertilizer before rice plants because roots of weeds are on the top of soil and need to be weeded as often as urea fertilizer is splited. If there is nitrogen deficiency or starvation during panicle initiation stage of paddy, yield is greatly reduced. In the land where USG is applied, number of panicles in the hills increases, size of grain is bold, due to which more yield is obtained and due to intake of sufficient nitrogen, amino acid in grain increases, which helps in increasing of protein. Use of USG can reduce nitrogen loss, which can significantly reduce harmful GHG emissions.
Due to covid-19 and Russia-Ukraine conflict, Bangladesh is facing a shortage of fertilizers and by importing fertilizers at high prices, government sells fertilizers at a low price within farmer's reach at a subsidized price to make it affordable for farmers. Government imports urea fertilizer at the rate of Tk 96 per kg and sells it to farmers at a subsidized price of Tk 26 so that cost of crop production of farmers is reduced. Government is subsidizing 70 thousand taka per ton of urea fertilizer. Domestic urea production plants are consuming 43.72 million cubic feet of gas to produce one ton of urea fertilizer while other countries are using only 25 million cubic feet of gas to produce same amount of fertilizer. So, domestic urea fertilizer production is also costing much more.
Farmers who have used USG once want to use it again but current management is supposed to make USG readily available but in reality, USG is not available in market. The recommendation to the concerned Ministry of the Government is that proper planning should be done on this excellent resilient technology and arrangements should be made to hand over USG to the farmers in paddy cultivation instead of prilled urea. Through which the country will save urea fertilizer, domestic currency due to urea import will be saved, production cost of farmers will be reduced, harmful GHG emissions will be reduced significantly, rice yield will increase, amount of protein in rice grain will increase by increasing amino acid and food and nutritional security of the country will be ensured.
Dr. M Monir Uddin, Agronomist, Consultant, GAIN Bangladesh
