Yet the use of artificial fertilisers increases crop yields and so what is the net effect?
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Equally disastrous is a subsidy on agricultural fertilisers, for which India's central government is responsible.
Mr Chidambaram has done the trick by increasing social spending and subsidies for food and fertilisers.
One of the biggest constraints on African farming is the inability to borrow money for fertilisers.
The prices of fertilisers are recovering more slowly than those of other commodities, making fertiliser companies relatively cheap.
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Huge quantities of gypsum and chemical fertilisers have been added to the waters of the Marcal and Raba rivers.
The potassium compound is used in fertilisers and the UK's only current mine is at Boulby in North Yorkshire.
But the mayor, Wilson Delgado, complains that prices for the crop are low, while those for fertilisers are rising.
This will eventually wash through to the river, as will nitrogen applied to those fields in the form of fertilisers.
It concluded that, thanks to carbon emissions from fertilisers and processing, some biofuels may cause more climate change than petrol.
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Agricultural fertilisers washed off the land by rain can cause algal population booms, making more food available to the larvae.
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Or nitrogen emissions (more exactly, NOx) from the use of artificial fertilisers contribute to climate change which will reduce crop yields.
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The company said test drillings indicated the area contained some of the world's biggest deposits of potash, which is used mainly in fertilisers.
There are reports that farmers are finding it hard to find credit to buy fertilisers and pesticides, which could affect next year's harvest.
They prevent the import of spare parts, chemicals for fertilisers and pesticides and all manner of machinery that might have some military purpose.
Writing in the journal Nature, researchers from the Geological Survey of India suggest that the increasing use of phosphate fertilisers might play a part.
Success would not only increase yields, but also reduce the need for water and fertilisers, since C4 plants make more efficient use of both.
Conventional farming methods using conventional fertilisers are adding active nitrogen to the soil, which tends to move to other places - lakes, rivers, seas, the air.
And, surprisingly, despite their rejection of most modern technologies, many of Mr Hostetler's neighbours quite like chemical fertilisers and pesticides: they kill the weeds faster.
Apatite, a phosphate, is a key raw material of some fertilisers.
Organic fertilisers were replaced by chemical ones in the 19th century.
Energy accounts for about three-quarters of the cost of producing nitrogen fertilisers, so cheaper gas and proximity to America's many farmers make Terra an attractive buy.
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In any case, the world-class agriculture in the delta employs advanced seed technology and chemical fertilisers, and does not depend on river-borne sediment of negligible nutrient value.
The aggressive use of pesticides and fertilisers has proved counter-productive.
Organic food, which is grown without man-made pesticides and fertilisers, is generally assumed to be more environmentally friendly than conventional intensive farming, which is heavily reliant on chemical inputs.
FAO, some 300, 000 hectares (1, 170 square miles) of land have simply been abandoned because of the collapse of the irrigation system and the lack of pesticides, fertilisers and machinery.
An expert on fertilisers at the University of London, Prof Andrea Sella, told the BBC it was possible that the highly explosive ammonium nitrate had also been stored on site.
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Improvements to tractors or fertilisers make it possible for one person to look after a slightly larger area each year, so farms get bigger and a few more people leave.
Embrapa scientists also bred varieties of rhizobium, a bacterium that helps fix nitrogen in legumes and which works especially well in the soil of the cerrado, reducing the need for fertilisers.
Private farmers cannot afford to buy pesticides and fertilisers.
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