AGRICULTURE REPORT - Irrigation and Salt

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AGRICULTURE REPORT -May 21, 2002: Irrigation and Salt

By George Grow
This is the VOA Special English AGRICULTURE REPORT.

Irrigation is the watering of land by other than natural methods. Irrigation projects provide water for crops in
areas that have long periods of little or no rainfall.

The United Nations Food and Agriculture Organization reports that only seventeen
percent of all cropland is irrigated¹. However, irrigated land provides forty percent of
the world’s food. Irrigation is said to increase production of most crops by one-
hundred to four-hundred percent.

However, F-A-O officials say about ten percent of all irrigated land has been
damaged by salt. This is most severe in extremely dry areas. As much as twenty-five
percent of the land is affected² in these areas.

F-A-O officials say this has become a threat to food security³. In the past, the U-N agency⁴ said that increasing the
use of irrigation could be the answer to feeding the world’s people. Now, it warns that rising salt levels in the
soil threaten much existing irrigated land.

Salinization is the build-up of salt in the soil. F-A-O officials say salinization reduces productivity⁵ and can
seriously damage the soil. It warns that salinization is reducing the world ’s irrigated land by one to two percent
each year.

All soil contains some salt. As water wears away rocks and soil, small amounts of mineral salts are carried into
rivers and other waterways. If a field has too little water, the mineral salts are not washed away. They remain in
the soil.

However, the worst danger to the soil is from too much water. When the ground is too wet, water levels rise. The
water evaporates⁶. However, salt remains⁷ underground, around plant roots. This interferes⁸ with the ability of the
roots to take in needed water.

The F-A-O says there are several ways to prevent or reduce salinization. One is for farmers to use just a little
more water than the crops need. The extra water can carry salt away from the roots of the plants. Farmers can
also build underground pipes or dig deep holes near crops. This can help remove extra water.

Finally, farmers can flood their fields. This can sometimes treat badly salinized land that can on longer be used
for agriculture. Adding a lot of water can be costly⁹. But F-A-O officials say it may be a wise economic decision,
depending on the value of the land and crops.

This VOA Special English AGRICULTURE REPORT was written by George Grow.

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