Athree-year experiment aimed at reducing the damage rats inflict on rice crops has
yielded promising results but faces an uncertain future with cash-strapped farmers
in Kampong Cham province.
More than 300 farmers in Samrong commune, Prek Chhor district, participated in the
project, which used a "trap barrier system", or TBS, developed in Malaysia
in the 1970s.
Before using the system, rice farmers in Samrong lost about half of their crop to
rice-eating rats, but after setting up the barriers and traps, losses fell to 20
percent, said Seth Sopheap, an agronomist working for the Cambodian Agricultural
Research and Development Institute (CARDI).
"I have seen the rat population decrease," said Sopheap, who spent most
of his time in the field working on the Farmer-Based Adaptive Rodent Management Research
project. "Recently I visited Samrong and heard the VDC [village development
council] wants to use the TBS."
The system works by using a 25-square-meter paddy of rice as a "lure crop."
The lure crop is enclosed by an 80-centimeter-high plastic wall, with openings in
the wall leading to one-way cages sewn onto the plastic.
Farmers and their families often eat the meat of the large paddy rats, which Sopheap
said are different to those found in the city and are safe for people to consume.
For the trapping system to work, however, farmers must develop a network of the traps
and barriers, with lure crops spaced about 200 meters apart.
"You cannot manage rats within your own plot of fields [because] rats live and
move beyond individual plots of rice fields," said Luke Leung, a rat expert
from Australia's University of Queensland, who was involved in the project.
The amount of crops lost to rats across Cambodia is difficult to quantify, Leung
said, but his "best guestimate is 17 percent" of total crops. What is clear
from previous studies is that Cambodian farmers rank rodents as the main pest damaging
While some farmers understand their local ecosystems and may be willing to work to
fight the rats, their efforts are undermined by others who do not.
"I think the most important issue to address rodent control [in Cambodia] is
to help farmers overcome this social problem," Leung said.
Another important issue for farmers was the cost of setting up the trap barriers.
Each one costs between $35 and $50, depending on the quality of material used, and
can be reused for three seasons. It takes a week to sew the barriers and traps together,
Sopheap said, and half a day to set them up in the field.
For the first year of the project, CARDI paid all the costs involved in setting up
the trap-barrier systems, but when they began asking farmers to contribute money
and labor, the numbers dropped, Sopheap said.
"I think if the farmers in our project site do not take up the technology that
we have introduced to them, uptake of the technology in other parts of the country
will be a big challenge," Leung said.
This could be bad news for farmers, who sometimes resort to pesticides imported from
Vietnam, with labels they can't read. Those who spray without protective gear or
who eat the small fish and paddy crabs from contaminated areas can become sick from
The use of state-funded bounties to reward the killing of pests, is not effective
because mice and rats breed faster than hunters can catch them, Leung said.
Heasn Vanhan, deputy director of the Department of Agronomy and Agricultural Land
Improvement at the Ministry of Agriculture, Forestry and Fisheries (MAFF), said trap-barrier
systems were a good idea for the off season, when a lure crop among otherwise empty
fields would attract rodents effectively.
"At the beginning of the rice season it's not a big problem ... but when the
areas near the Vietnamese borders start flooding, the rats will move towards the
wet-season rice," Vanhan said.
He said there were a range of techniques to reduce rat populations, including rodenticide
and placing baited bamboo tubes in fields to act as cheap and simple traps.
Vanhan said the 10 trainers employed by his department also conducted "rat field
days" to educate farmers about rodent control.