Improved Irrigation to Reduce Arsenic Found in Rice

Improved Irrigation to Reduce Arsenic Found in Rice



January 2008  - Improved irrigation practices in 
Asia could reduce the high levels of arsenic found in rice, the United 
Nations Food and Agriculture Organization, FAO, said Wednesday, warning of 
the increased food safety risk posed by the toxic substance. 
The agency says that arsenic enters the food chain mainly through crops 
absorbing contaminated irrigation water. 
An odorless and tasteless semi-metal that occurs naturally in rock and 
soil, when igested arsenic can lead to a variety of illnesses including 
skin disorders, gangrene and cancer of the kidneys and bladder. 
Currently, 12 Asian countries have reported high arsenic levels in their 
groundwater resources. 
"The problem of high arsenic levels in crops, particularly rice, needs to 
be urgently addressed by promoting better irrigation and agricultural 
practices that could reduce arsenic contamination significantly," said FAO 
water quality and environment officer Sasha Koo-Oshima. 
"Arsenic contaminated rice could aggravate human health when consumed with 
arsenic laden drinking water," she warned. 
The agency's warning is contained in a new report entitled "Remediation of 
Arsenic for Agriculture Sustainability, Food Security and Health in 
Bangladesh." 
Koo-Oshima said, "The widespread addition of arsenic to soils, for example 
in Bangladesh, is degrading soil quality and causing toxicity to rice. 
Arsenic contamination is threatening food production, food security and 
food quality." 

Millions of shallow tube wells have been installed throughout Asia over 
the last 30 years pumping water from contaminated shallow groundwater 
aquifers. 
Contamination originates in arsenic-rich sediments of the Ganges and 
Brahmaputra river that filters into groundwater water pumped to the 
surface through the tube wells. 
Bangladesh, where rice is a staple food and consumed in large amounts, has 
the highest percentage of contaminated shallow tube wells and an estimated 
30 million people are dependent on those wells for drinking water and 
irrigation. 
A pilot study conducted in Bangladesh by FAO and Cornell University show 
that planting rice in raised beds around 15 centimeters above the ground 
and not in conventional flooded fields reduces the exposure to 
contaminated irrigation water and produces higher yields. 
In addition, the raised bed rice acts as a buffer against floods and 
drought and serves as a measure in climate adaptation. 
A related Cornell University project found that between 30 and 40 percent 
less irrigation water is needed in the raised bed system. Fertilizers are 
also captured better, so farmers will need less fertilizers. 
"The raised bed system represents a major shift in rice production," said 
FAO, "but tests show that farmers prefer the new approach due to visibly 
higher yields, water savings, lower tillage and labour costs and 
production of a safer crop." 

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