April 20, 2010 7:47 pm
SCIENCE CITY OF MUNOZ, Nueva Ecija, April 20 — In the light of the continued dry spell that hit the country, the Philippine Rice Research Institute (PhilRice) has recommended to farmers to practice controlled irrigation (CI) to optimize the use of water.
“A little water can go a long way,” said Jovino de Dios of the PhilRice Agronomy, Soils, and Plant Physiology Division.
When paddy water depth reaches a five-centimeter (cm) depth from the soil surface, farmers can stop irrigating their fields so that other farmers may benefit even those at the tail end, de Dios explained.
He said water should be brought into the rice paddies only when the paddy water is about to leave the root zone of the rice plant.
This can be facilitated by installing an observation well into the paddy soil up to 15 cm deep in the wet season or 20 cm deep in the dry season from the soil surface, he said.
The CI method allows farmers to bring in irrigation water at the right time and right amount, he also said.
The CI technology was developed by PhilRice, International Rice Research Institute, and the National Irrigation Administration from 2001 to 2004.
“The technology stabilizes soil and plant base minimizing crop lodging, facilitating farm mechanization, and correcting some problems on soil nutrient imbalances such as zinc deficiency,” De Dios said.
It also reduces farm inputs such as oil, fuel, and labor, he added.
A study led by De Dios showed that CI can reduce the amount of water used in irrigated lowland rice without reducing yield.
It also decreases the amount of water by 11-15 percent in shallow tube wells and 20 percent in deep wells as shown in studies conducted in Nueva Ecija and Tarlac.
In terms of yield, a study conducted by PhilRice showed that using less water does not decrease yield.
Before practicing CI, members of the Pook Malaya Irrigators’ Association in Sto. Domingo, Nueva Ecija harvested four tons/hectare (t/ha) during the 2007 wet season.
When they started to practice the technology, farmers yielded more than five t/ha during the 2008 wet and dry seasons. In the 2009 dry season, they produced more than six t/ha.
In coping with limited irrigation water, De Dios said farmers need to remember that rice can last for 30 days after planting in clayey soil, and 15 days after planting in sandy loam soil with saturated soil to field capacity.
The first irrigation of at least three cm depth should be done as soon as rice leaves curl at around 12 noon, he noted.
Yield losses may occur if leaves start curling at 10 a.m. or earlier, he said.
He further explained that soil wetted by occasional rain may be enough to sustain the plants until the crucial panicle initiation and flowering stages.
Many countries including places in Southeast Asia will face economic-water scarcity by 2025, the Sri Lanka-based International Water Management Institute reported.
The Food and Agriculture Organization of the United Nations also said that by 2025, 1.8 billion people will be living in countries or regions with absolute water scarcity. (PNA)
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