SPREADING waste from power stations over fields can boost the yield of food
crops. The waste helps water infiltrate the soil, reducing runoff and soil
loss.
The scrubbers that clean the emissions of coal-burning power stations produce
gypsum, which is also found naturally. Sulphur dioxide gas reacts with ground-up
limestone in the scrubbers to form the calcium sulphate mineral.
Darrell Norton of the US Department of Agriculture鈥檚 National Soil Erosion
Research Laboratory in West Lafayette, Indiana, found that using the waste
product cut soil loss by a quarter in the lab. 鈥淣ew technologies to improve air
quality have produced more and more gypsum by-products with potential for
beneficial use in agriculture,鈥� says Norton, who presented his findings to the
10th International Soil Conservation Conference in West Lafayette last
month.
Advertisement
Ken Curtis, a farmer from Prairie City, Illinois, who is taking part in
Norton鈥檚 field trials, found that spreading 11 tonnes of gypsum on each hectare
of his fields raised the harvest of soya beans by almost 7 per cent. 鈥淚 didn鈥檛
expect that much response,鈥� he says.
快猫短视频 of the technique has spread and farmers are now asking power stations to
supply them with gypsum. Power plants in the US produce about 100 million tonnes
each year, enough to provide over two tonnes per hectare for a quarter of US
farmland.