quality if for liming
Look for you go in
quality if for liming
By Andrew Blake
MAKE sure you know what you are getting when you employ someone to spread lime on your land.
That is the message from an East Anglian liming contractor as business picks up after a quiet spell. Applying an inappropriate product which may remain unavailable for years could waste both time and money, warns Bury St Edmunds-based Keith Mount.
He urges growers to focus on product quality. In the latter days of the ministrys lime subsidy, which came to an end in 1976, grants were linked to quality.
Now the wide range of materials on offer, sometimes as by-products of other industries, can make it hard for growers to assess the likely benefits, notes Mr Mount.
About 85% of the liming materials spread by his firms subcontractors is chalk, and about 15% magnesian limestone. The latter has a higher neutralising value – 59% against chalks 46-52% – and at about £17/t spread can be an economical way to correct magnesium deficiencies, he says.
However, for growers in East Anglia haulage difficulties from Notts and Derbyshire mean magnesian limestone is less readily available than chalk.
Chalk comes in two main forms, screened and ground. But within those categories there is a wide range on offer, says Mr Mount. The finer the particles the more easily the chalk acts to offset acidity, he explains.
Screened chalk, from 25mm (1in) to dust, currently costs about £15/t spread. Ground chalk, with all the particles below 6.3mm (0.25in), is up to £18/t. "Unfortunately there is no EC specification. That opens up the door to inferior products.
"We also offer screened limestone, without magnesium, in the north-west of our area and Lincs where there are no chalk quarries. Its neutralising value is higher, 50-54%, but it needs to be finer than chalk because it is harder and breaks down more slowly in the soil.
The current limestone price range of £8-13/t largely reflects the quality, he suggests. "There is a huge range of products out there and I just hope that more control will come in time."
Only by treating liming materials more precisely will growers be able to get the best from them, Mr Mount suggests.
Sugar beet is a key driver for his operations in Norfolk and Suffolk with many of the current applications by the firms 14 subcontractors directed at the 1999 crop. Ploughed down this autumn and returned near the surface next year the lime should ensure correct seed-bed pH for that seasons sowings, he explains.
"But everybody has their own ideas. We do quite a lot of top-dressing as well."
Waste lime from beet processing factories may appear a cheap option. But contra-accounting may mean some growers fail to appreciate its true cost, comments Mr Mounts.
Second wheats will often benefit from higher pHs than many growers believe, he adds. "You really need to be approaching 7 to avoid the worst effects of take-all."
* A spokesman for the Agricultural Lime Producers Council points out that lime production is covered by British Standards and close contact is maintained with MAFF and ADAS.
LIMING
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* Big range of products.
* Particle size important.
* Transport cost barriers.
* Quality control gap?
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Check lime quality rather than choosing on price alone, warns East Anglian spreading contractor Keith Mount.
LIMING
• Big range of products.
• Particle size important.
• Transport cost barriers.
• Quality control gap?