Text and Photos by Henrylito D. Tacio
Rice, one of the most versatile foods, was recovered from a grave at Susa in Iran around the first century AD. Today, most of the rice produced in the world comes from Asia, including the Philippines.
Rice is the primary food for about 50 percent of the world’s population, according to the Laguna-based International Rice Research Institute (IRRI). “Rice is a plant that grows best in wet soil, with its roots flooded,” says L. Hartwell Allen, an American soil scientist at the Crops Genetics and Environmental Research Unit in Gainesville, Florida. “But flooded rice crops emit substantial amounts of methane to the atmosphere.”
After carbon dioxide, methane is the second most important greenhouse gas, which is responsible for trapping the heat from the sun at it radiates back into space. Methane is created naturally as a waste product of anaerobic bacteria (living with little or no oxygen). These bacteria produce methane gas in waterlogged soil and wetland, but also in human-produced environment such as rice paddies.
Scientists explain that long-term flooding of the fields cuts the soil off from atmospheric oxygen and causes anaerobic fermentation of organic matter in the soil. During the wet season, rice cannot hold the carbon in anaerobic conditions. The microbes in the soil convert the carbon into methane which is then released through the respiration of the rice plant or through diffusion of water.
Concentration of methane in the atmosphere has more than doubled during the past 200 years, scientists claim. Riceland has been cited as one of the major contributors of methane in the atmosphere.
“An estimated 19 percent of world’s methane production comes from rice paddies,” says Dr. Alan Teramura, a botany professor at the University of Maryland. “As populations increase in rice-growing areas, more rice – and more methane – are produced.”
Aside from rice paddies, the other top sources of methane in the atmosphere are wetland (20.2 percent), ruminants or cud-chewing animals like cattle (14 percent), biomass fires such as burning forests (9.7 percent), oil and natural gas pipeline leaks (7.9 percent), termites (7 percent), coal mining (6.2 percent), landfill (6.2 percent), animal wastes (5 percent), and sewage (4.4 percent).
Methane gas traps heat as efficiently as carbon dioxide, the IRRI points out. One molecule of methane from decaying rice paddies is about 10,000 times more efficient in heating up the earth than one molecule of carbon dioxide emitted by a gasoline engine.
Methane also contributes to the depletion of the ozone layer, which acts as a shield against the deleterious radiation of the ultra violet rays of the sun. The ozone layer is the upper atmospheric layer of air above the earth.
By trapping the heat (infrared radiation) that the earth emits, greenhouse gases increase the planet’s surface temperature and altering the global climate. Scientists call this phenomenon as global warming.
“The global warming is very simple,” said Dr. Robert Watson, chairman of the United Nations Intergovernmental Panel on Climate Change (IPCC). “We are increasing emissions of greenhouse gases and thus their concentrations in the atmosphere are going up. As these concentrations increase, the temperature of the earth rises.”
“Global warming is an environmental threat unlike any the world has faced,” writes Christopher Flavin in his paper, Slowing Global Warming: A Worldwide Strategy. “While human activities during the past century have damaged a long list of natural systems, most of these problems are local or regional in scope and can be reversed in years or decades if sufficient effort is exerted.”
But global warming is different. “Changes to the earth’s atmosphere are global and – for all practical purposes – irreversible not only in our lifetime but in our children’s and grandchildren’s as well,” Flavin warns.
If not soon solved, global warming is most likely to make the world a hostile place to live in. This is more so in the Philippines, which is currently home to more than 90 million people. “Global warming could result in a wide range of catastrophic consequences: rising sea levels threatening archipelagic states, low-lying coastal areas and fertile deltas; increased frequency of hurricanes, droughts and other extreme climate events; disturbance of ecosystems; greater aridity; and greater pressures on freshwater resources,” said ex-Senator Heherson Alvarez, former chairman of the Senate Committee on Environment.
Since rice farming is one of the culprits cited in the production of methane in the atmosphere, the Appropriate Technology Center (AproTech) of Xavier University in Cagayan de Oro City is batting for the raising of ducks in rice farms.
Ducks in the rice paddies can effectively reduced the emission of methane into the atmosphere, said Dr. Rachel Polestico, a physicist and lecturer at the university’s South East Asia Rural Leadership Institute.
Dr. Polestico, who is the AproTech executive director, calls the scheme integrated rice-duck technology. Citing various scientific studies, he explained that ducks effectively suppress methane emission from rice paddies because of the ducks’ constant paddling.
The rice-duck technology was introduced in Zamboanga del Sur last year. The system was cited as one of the reasons why a surplus in rice production – by over 16,000 metric tons – was reported last year.
The favorable weather condition and irrigation system, coupled with the use of certified palay seeds (by the Department of Agriculture) and new methods in rice farming contributed much in the sufficient rice production last year, said Governor Antonio Cerilles.
One of the new methods in rice farming was the raising of ducks in rice paddies. Nonoy E. Lacson, author of the report, wrote: “Under the system, ducklings are released to rice fields to graze and feed. The paddling movement of the ducks in the rice fields increases the rice tillers, in effect raising annual yield by as much as 10 to 15 percent. Besides their paddling, ducks also eat the insects and unwanted weeds in the rice field.”
According to the agriculture department, the integrated rice-duck farming system is one of the best strategies in increasing rice productivity as it reduces labor and inputs characterized by its devoid use of artificial fertilizers and chemicals. Thus, shift from conventional way of planting using inorganic materials to this technology provides additional source of income and food to farmers.
The said technology is environmentally sound as it restores the relationship of people with nature. This is a sustainable system as it helps in eliminating the contamination of soil, water and air brought by chemical substances which are harmful to both nature and human.
“The integrated rice-duck technology reduces the use of chemicals,” the agriculture department points out. “Since ducks are grown alongside rice paddies, they eat harmful pests at the same time their dung fertilizes the soil. Their paddling movement cultivates the soil and destroys the weeds. Its benefits to the farmers are immediately felt and tangible.”
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