Turning back agriculture's dirty tide of water

Algal bloom in a Canadian prairie lake. The bloom is caused by a buildup of nutrients from agricultural fertilizers entering the water and can lead to fish kills.

Contaminated water is a public enemy. It kills millions of people worldwide every year. And agriculture -- the single largest user of fresh water, consuming an average 70 percent of global surface water supplies, much of which is recycled -- has a lot to do with contamination, says a new FAO report.

Agriculture discharges pollutants such as chemical pesticides and fertilizers into surface and groundwater. Poor farming practices can lead to soil erosion and sediment buildup, while inefficient irrigation schemes can cause waterlogging and salinization that destroys soil fertility and poisons groundwater with concentrated salts and minerals. Completing the cycle, the use of wastewater and polluted surface and groundwater contaminates crops and transmits diseases to consumers and farmworkers alike.

One of the most tragic examples of how deeply flawed farming practices have led to water contamination and related health problems can be found in the Aral Sea Basin of Central Asia. Here hundreds of thousands of people suffer from anaemia and other diseases because of drinking-water laden with salts and chemical cocktails from the cotton fields.

Water pollution is now a global phenomenon, though more so in rich countries than in developing ones because of chemical pollution from the greater use of fertilizers and pesticides. "In many countries, pollution can no longer be remedied by dilution in rivers and lakes," says FAO specialist Dr Arumugam Kandiah. "We are facing a buildup of nasty contaminants and freshwater resources are suffering."

Many specialists see a crisis looming that could threaten global food security. The report warns that unless measures are taken to check contamination there could be a further decline in freshwater and coastal fisheries. Nor is this the only concern. "If the cost of remediation exceeds economic benefits, development projects may no longer be creditworthy," warns the report.

Given the need to increase food production to feed a growing world population, the challenge is to ensure that farming methods do not adversely affect water quality. So far, controls imposed by municipal and government agencies in many rich and developing countries have checked factory pollution, but now a strategy is needed which also checks water contamination at the farmgate. So what's needed?

"Farmers need to be aware of the impact of their farming on the downstream water quality," says Dr Kandiah. "If they are causing pollution, then they need to take preventive action whether it be building silt traps, or whatever. And one way is to internalize the cost of remedial measures into the production costs."

Source: Control of water pollution from agriculture, FAO 1996
FAO Irrigation and Drainage Paper 55 ISBN 92-5-103875-9
The publication synthesizes existing information and case-studies on water pollution caused by agriculture and provides a framework for practical measures to be undertaken by farmers, decision-makers and others working in this area to control this growing problem.

See FAO's:

Land and Water Development
How to order publications

Such an approach requires educating farmers and agricultural planners. "We need to create a scientific understanding," says Dr Kandiah. This involves training at various levels. One proposal is to extend the provision of information and advice on issues like best land and water management practices electronically on the Internet.

Clearly, a legislative framework including new standards policed by monitoring agents is critical. But rather than imposing punitive measures on farmers who do not comply with environmental regulations, as happens in parts of Europe, built-in incentives could help encourage farmers to monitor water quality and adopt best practices.

A contentious point in today's free market world. But what is clear, is that new ways are needed to hold back agriculture's growing tide of dirty water.

27 January 1997


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