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Monday December 9, 2013 MYT 12:00:00 AM
Monday December 9, 2013 MYT 7:01:25 AM
by tan cheng li
Rice cultivation is a source of greenhouse gases; the use of fertiliser releases nitrous oxide while straw decomposition in flooded rice fields releases methane.
RICE grows best when the daily temperature is between 24°C and 35°C. Any higher, yields will plunge.
Current temperatures show a warming trend but according to Malaysian Agricultural Research and Development Institute (Mardi) researcher Dr Mohamad Zabawi Abdul Ghani, they are still within the optimal requirement for rice cultivation.
“If the temperature reaches above 35°C, production of rice will be affected. An increase of 1°C above 35°C will cause rice yield to drop 10%,” shares the deputy director in the agroindustry and environmental management programme. High night temperature can also cause a reduction in carbon, hydrogen and oxygen reserves, leading to empty grains.
Dr Zabawi points out that during the 1997-1998 El Nino weather event (abnormal warming of surface ocean waters in the eastern tropical Pacific) which saw less rainfall and high temperatures, the country’s rice production dropped 1.15%, incurring losses of RM160mil.
“This is indication that if the temperature rises above the optimum, there is a possibility of reduced rice production.”
To adapt to the changing weather, he says, farmers might have to change the sowing time to match new rainfall distributions. He is conducting a study on this. Breeding rice varieties tolerant to climate change is another vital measure. Mardi’s Rice Research Centre has developed a rice hybrid that needs little water. Test fields of the so-called “aerobic rice” are being set up.
The variety requires half the water needed in flooded rice farming and is irrigated through a sprinkler system.
Mardi researchers have identified a drought-tolerant accession which will be used to develop a variety that can withstand dry weather. They are also trying to determine a flood-tolerant trait. Zabawi says more efficient use of water is also necessary to ensure sustainable agriculture in a future world that will be dryer. Current irrigation efficiency is only about 45%.
While changing weather patterns will affect rice cultivation, the activity itself also contributes to global warming. In Malaysia, agriculture contributes to 3% of the total greenhouse gas emissions.
The emissions come from flooded rice farming (32%), agriculture soils (through use of fertiliser, 30%), manure from livestock (22%) and enteric fermentation (digestion process in ruminants, 16%). Greenhouse gases released from rice farming are traced to emissions of nitrous oxide (from fertiliser) and methane (from straw decomposition in flooded rice fields).
Dr Zabawi says curbing greenhouse gases from rice fields calls for better management of rice straw as well as fertiliser and usage. Farmers need to practise precision farming in order to minimise use of fertiliser, and switch to bio-fertiliser. “They must have a proper schedule to apply fertiliser, at the right time and right amount.”
He says the current practice of ploughing back the straw into the soil is still the best method as emissions are lower than when the straw is burnt. The straw can also be turned into compost and animal feed but collection will be difficult as padi fields are scattered.
There must also be a good water delivery system to farms and monitoring to maintain the right water levels; if it is too high and the straw is submerged for too long, more methane is released during decomposition.
Dr Zabawi is also testing the application of organic materials (chicken dung, rice ash and compost) in rice fields. Bacteria in these materials will speed up straw decomposition and reduce the time that the waste is left in the fields.
As for greenhouse gases released by livestock, Dr Zabawi is studying different types of animal feed to see how much methane is generated during digestion. His team will then consider formulating a feed using ingredients that will lead to less methane generation.
Saving our rice bowl
Tags / Keywords:
Environment, Ecowatch, climate change, adaptation, rice farming
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