Prilled MagLime

Also available, Prilled Lime.

Recommended Application Rate

250 kg per hectare.

Ultra-Fine Particle – The Facts


                                                                                                                                                                                                                                           pH Change Over Time

It’s important to understand that it’s not the “Tonnes per ha” that raises pH, it’s the available “Surface Area of Calcium Carbonate” that counts.

To explain: A 2mm chip of Ag-lime has a surface area of 24 square mm. If that same 2mm chip is ground to less than 20 micron lime flour, the surface area of available Calcium Carbonate increases from 24 square mm to an astonishing 2,450 square mm, the same principle applies to phosphate and magnesium rocks.

The graph shown on the right (American scientific testing), clearly shows that as lime particle sizes are reduced, the effect of liming is not only dramatically faster and far more effective in raising pH, but that the increase is also much longer lasting than coarser liming material. The dotted blue line has been added to the graph by the manufacturer and is where they believe that the less than 20 micron Prilled Lime Flour product would fit.

New Zealand laboratory farm soil testing, shows that if your farm has had a history of Super phosphate applications, you will most likely have between 500kg and 1.3 tonnes of lock-up phosphate reserve in the top 150mm of every hectare on your farm. By monitoring the levels of these valuable reserves you can confidently take advantage of them by simply raising soil pH.

Soil pH – The Key to Increased Farm Productivity

                                                                                                                                                                                                                                              Nutrient Availability Chart

The chart shown on the right (found in soil science text books), reveals that optimum plant nutrient availability is achieved between pH 6.0 and 6.5.

It can be seen that potassium is only about 30% available at pH 5.0 however it is 100% available by 6.1. Perhaps the most dramatic example of nutrient availability is phosphorus which is approximately 25% available at pH 5.5 but is 100% available at 6.5.

The implications for farms applying a phosphate fertiliser when soil pH is below 6.0 is that approximately 70% of the applied plant available phosphate is locked-up with a few days. The good news, as the chart shows, is that raising pH releases locked up nutrients. A further advantage of raising soil pH is that the majority of phosphate solubilising soil fungi and bacteria are most efficient at pH 6.0 and above.

Aluminium is perhaps the most significant of all. Are you aware that available aluminium is highly toxic to plants and stunts their root structures? Raising soil pH locks up aluminium, resulting in dramatic increases in pasture roots depths. This increases both pasture production and drought resistance.

It makes sound financial sense to raise soil pH and this Prilled MagLime product makes it easy.

Prilled Lime Frequently Asked Questions (FAQ)

NOTE: While the following applies specifically to the Prilled Lime product, much of what is covered below also applies to the Prilled MagLime + Sulphur product (which is 76.8% Limestone).

QUESTION: How can 250 kg/ha be as effective as 2.5 tonne/ha of conventional Lime?
ANSWER: When it comes to Lime, “It’s not the tonnes per ha that raises pH, it’s the available surface area of Calcium Carbonate that counts”. It’s a scientific fact that reducing particle size increases Lime’s efficiency exponentially because, as particle sizes are reduced the available surface area of its Calcium Carbonate content increases dramatically. To explain, a single 2mm chip of limestone has a surface area of only 24 square mm, however if we grind that same 2mm chip down to less than 20 micron we increase the surface area to an astonishing 2,400 square mm.

Over the past 50 years, scientific work in the USA, Scandinavia and Australia clearly deomonstrates that finely ground particles of Lime have a much greater and swifter effect on raising soil pH than coarse particles.

It’s unfortunate that those who continue to denounce the effectiveness of fine particle Lime must be basing their opinions on well-outdated scientific tests and models that “assumed” Lime particles of less than a quarter of a mm were 100% available. The widely held belief that the coarse particles in conventional Lime become effective over a couple of years after application has been proven to be a fallacy.

QUESTION: How quickly will it work?
ANSWER: Prilled ultra-fine particle products start to break down as soon as they become wet from rain or even heavy dew. As the prills break down the fine particles enter the soil quickly raising soil pH. Tests show that the fine particle Lime will have become fully effective in a matter of weeks after significant rain.

QUESTION: Will it last?
ANSWER: Yes, of course! To understand why, we need to understand a few basic facts:

  • It is the carbonate in Lime (not the Calcium), that raises pH by neutralising the acidic Hydrogen in the soil;
  • Soil pH gradually becomes more acidic over time. This is a result of natural soil processes including the fact that, as plants remove alkaline nutrients from the soill they leave acidic Hydrogen behind. As a rule of thumb soil pH will drop by approximately 0.1 per year if no liming materials are applied.
  • When we apply Lime and the carbonate has raised soil pH, the Lime has done its job. The reason that soil pH gradually becomes more acidic after liming is not because the Lime has “run out’, it is just a natural process.
  • From the above you will be able to understand that, if we apply any liming material that raises soil pH by say 0.2, and over the following two years natural processes drop pH by 0.1 per year, then as far as soil pH is concerned, at the end of year two the soil pH will be back to where we started.
  • So, whether we quickly raise soil pH by 0.2 by applying only 250 kg/ha of high purity ultra-fine particle Lime, or slowly over a year by applying 2.5 tonnes of a coarse liming material, the lasting power is the same.


In conclusion, you can be confident that low application rates of Prilled Lime will give you fast results that will last.

QUESTION: Being so fine will it leach away?
ANSWER: Fine particle Lime does not leach away. Liming is a chemical reaction between the carbonate in the Lime and the acidic Hydrogen left by plants on the soil’s Cation Exchange Sites. The end result of the liming chemical reaction is that the carbonate combines with the acidic Hydrogen producing CO2 and water. This reaction leaves the Calcium (that was the Lime), chemically bonded to the Cation Exchange Site. Unlike coarse particle products, the ultra-fine Lime particles in Prilled Lime do have the ability to penetrate deeper into the soil structure where they are able to also raise sub-soil pH.

QUESTION: How do I decide on a Lime application rate?

  • The first step is to decide on your target soil pH level. Our research shows that a pH between 6.0 and 6.3 is an optimum level. In this range nutrients and trace elements are chemically most plant available and also above pH 6.0 the soils microbial life are also at their most active.
  • Understand that soil pH drops naturally by about 0.1 per year, and that our experience shows that to counteract that change will require either 100 kg/ha of Prilled Lime or 1 tonne/ha of good quality Ag-Lime (depending on soil conditions).
  • Decide whether you wish to maintain, or to raise your existing pH levels. If you wish to maintain your existing levels use the application rate in point 2 above.
  • If you wish to raise pH levels then we suggest applying between 100 and 300 kg/ha of Prilled Lime or 1 – 3 tonnes/ha of good quality Ag-Lime.