Better Irrigation Use Could Reduce Arsenic Threat

Better irrigation methods could reduce arsenic threat in rice, says UN agency

Improved irrigation practices in Asia could reduce the high levels of arsenic found in rice, the United Nations Food and Agriculture Organization (FAO) said today, warning of the increased food safety risk posed by the toxic substance. Improved irrigation practices in Asia could reduce the high levels of arsenic found in rice, the United Nations Food and Agriculture Organization (FAO) said today, warning of the increased food safety risk posed by the toxic substance.

The agency noted that arsenic - an odourless and tasteless semi-metal that occurs naturally in rock and soil - enters the food chain mainly through crops absorbing contaminated irrigation water. It 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," FAO water quality and environment officer Sasha Koo-Oshima said.

"Arsenic-contaminated rice could aggravate human health when consumed with arsenic-laden drinking water. 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," she noted.

Millions of shallow tube wells have been installed throughout Asia over the last 30 years pumping water from contaminated shallow groundwater aquifers. 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 centimetres above the ground and not in conventional flooded fields significantly 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 per cent less irrigation water is needed in raised-bed- system. Fertilizers are also captured better - with the effect that farmers will need less fertilizers.

"The raised-bed system represents a major shift in rice production 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," FAO stated.

ENDS

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