Agricultural Lime Association - Mineral Products Association
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Are you neutralising your bank balance?

There are few improvements so easily and cheaply carried out which can have so fundamental an effect on the success or failure of crops and farming as the application of agricultural lime. Do you know whether the lime you are buying is both value for money and correct for your soil type?

The Agricultural Lime Association has produced these essential guidelines that farmers should consider before purchasing and using lime.

Points you should consider when purchasing Agricultural Lime

Soil analysis

  • Get soil professionally tested.
  • Take a representative number of spot samples rather than a composite laboratory sample to CLEARLY identify specific low pH areas.
  • BDH field testing identifies the 'real' soil environment and pH; oven-dried laboratory samples invariably give higher readings in the absence of moisture.
  • Maintain an average of pH7 on arable and pH6.5 on grassland.

Liming Materials (LM)

  • For your protection and assurance LM are regulated by the Fertiliser Regulations 1991 -
  • Ask which material your merchant/supplier is proposing, check its specification in the regulation - is it suitable?
  • Check the pH levels and product application rate on the ALA Lime Calculator -
  • Ask the producer for a 'Product Specification Datasheet'
  • Check the Neutralising Value NV - this is the strength of the product to reduce/neutralise acidity, it varies from @ NV 44 to NV 57 - a 30% difference.
  • Ask about Reactivity Value - this is the speed of the LMs' reaction within the soil, and is directly related to parent rock and the degree of milling - the higher the percentage passing 150 microns, ideally > 40%, the quicker the product will be absorbed in the soil solution to reduce and neutralize acidity.
  • Check the specification to see how much of the product is calcium, and how much INERT Silica. The amount of inert and valueless silica can vary from 1 - 2% up to 20 - 30% - whilst the deal was attractive, in practice this only neutralises your bank balance, NOT your soil.

Cost comparison

  • Liming materials should be purchased on the basis of the price relative to the NV and fineness of products on offer.
  • To ascertain best value, divide the LM price by the known NV to get the unit cost, and then examine the % passing 150 micros, ideally 40% but a minimum of 30%.
  • Plus 150 micron material is of no short term liming value.

Legal requirements

  • The 1991 Fertiliser Regulations control the sale of agricultural liming materials. Quarry produced materials can be sold under a number of permitted names (the term ‘Agriculture Lime’ alone is not sufficient). Each name has a precise meaning and associated declaration, which are required by law.
  • Legally supplied weight tickets should include, at the time of delivery as a minimum:
    • Name of the material – and/or trade name
    • The Neutralising Value
    • The % by weight of material passing through a 150 micron sieve

Why maintaining the appropriate pH makes sense

  • Arable pH 7.00, Grassland Ph 6.00 – 6.80 is best suited for optimal nutrient uptake and utilisation.
  • Maintaining optimal pH reduces the solubility and transmission of Heavy Metals in the soil
  • Improved soil structure for easier working, reducing power/energy costs.
  • Improved fauna and microbiological soil activity helping to breakdown vegetable matter and improve soil organic matter levels. 
  • Protecting the environment

Maintaining a detailed pH record and history is an essential chapter of any Soil Management Plan.  Drainage, Structure and pH are the three foundation blocks on which any successful farming enterprise depends; omitting to address any of these points will limit the potential yield and structure of the soil. 

“Never allow your soil to know your worth”


Further information on liming materials can be obtained from [email protected]





Legal requirements

The Fertiliser Regulations control the sale of agricultural liming materials. Quarry produced materials can be sold under a number of permitted names (the term ‘Agriculture Lime’ alone is not sufficient). Each name has a precise meaning and associated declaration, which are required by law. These are described in the Fertiliser Regulations Act. Legally supplied weight tickets confirming the NV and fineness should be supplied by the quarry not the supplier. If these cannot be provided farmers should not buy the product. Farmers should ensure that these names are available to them at the time of delivery (as required by law) and that the lime quality is clearly identified at time of quotation.

The decline in the use of lime has resulted in an increase in the proportion of soil samples exhibiting pH values below optimum in several regions across the UK. It’s use has become undervalued as an input into agriculture, and farmers need to be more proactive when it comes to buying lime products.

Michelle Folley of Midland Lime Ltd based at Northampton says ‘With ever decreasing on farm margins it is important farmers get the correct professional advice to lime where and when required; and that the correct product is supplied in accordance with Fertiliser Regulations to rectify pH problems correctly’.

Natural agricultural lime is used to correct acidity in soil and provide the right conditions in which crops and other plants can grow. Unless steps are taken to redress the balance of soils by applying a liming material there will be a natural reduction in the lime status in most soil. In turn this may reduce soil fertility.

For further information please contact Stephen Hill via [email protected]

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