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November 12, 2007
Wagdy Sawahel,
SciDev.Net
Researchers led by the Syria-based
International Center for
Agricultural Research in the Dry Areas (ICARDA) have
developed a low-cost technology to increase crop yield in
magnesium-rich soil.
Excessive amounts of magnesium in soil and irrigation water lead
to soil degradation as a result of its effects on the soil's
physical structure. The magnesium level also affects the amount
of other nutrients in the soil, causing a gradual decline in
crop yields.
More than 30 per cent of irrigated lands in southern Kazakhstan
contain excess magnesium, leading to low cotton productivity.
Researchers at ICARDA and the Kazakh Research Institute of Water
Management conducted four-year trials in magnesium-rich soils on
farms in the Arya Turkestan area of southern Kazakhstan.
They added phosphogypsum, a waste product of the phosphorus
fertilizer industry and a source of calcium — which improves the
physical and chemical characteristics of soil — to the fields.
They found that adding an appropriate level of phosphogypsum —
determined by simple soil tests — doubled the cotton yield.
A paper detailing the research is due to be published in an
upcoming issue of international Land Degradation & Development.
Manzoor Qadir, ICARDA-based marginal water management scientist
and head of the initiative to out-scale phosphogypsum technology
in central Asia, said in a press release, "[The method] works
out very economical for the farmers. It is enough if the farmers
apply phosphogypsum once every four to five years."
Magdi Tawfik Abdelhamid, a botanist at Cairo's National Research
Centre, told SciDev.Net that the new method "is a cheap, simple,
reliable and promising tool for increasing cotton yield in
high-level magnesium soil in other cotton-producing developing
countries such as Egypt, Sudan and Syria".
He also called for programmes and field experiments to be
launched in irrigated areas in Africa and Latin America to
evaluate the effects of phosphogypsum application in those
regions.
Researchers have indicated the need to assess any risks
associated with phosphogypsum transportation and application by
farmers, as some grades of phosphogypsum can contain relatively
high levels of radioisotopes.
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