The Value of Granular Lime
Granular lime is a useful tool for bringing soil pH up to a more desirable range in an acid soil. This increases the availability of some elements including molybdenum and phosphorus and decreases the toxicity or phosphorus lock up problems from aluminium, manganese and iron. A pH of 5.8 to 6.2 is desirable in most pasture situations and also allows good activity of soil fungi, soil bacteria and earthworms. Limeflo does not replace the use of granular lime in very acidic soils unless it is used annually. Limeflo is able to promote improved soil conditions and pasture growth without necessarily a long-term lift in pH. It can be used to enhance the effectiveness of any granular lime applications.
Does granular lime include fine lime?
There is fine lime in granular lime – this is the fraction of granular
lime that has a relatively quick effect. Unfortunately, it makes up only
a small percentage of the product and the soil biological activity results do
not match the use of very fine Limeflo applied by suspension.
On average, granular lime particle size is about 1 mm and calcium release is
steady but never gives as great a boost in soil solution calcium as Limeflo
can.
When you see lime applied by bulk spread, the dust being blown in the air (Drift) is much of the relatively fine lime and any very fine Limeflo will often be going up into the atmosphere. (At 20 micron or less equates to the same size as many fungal spores which travel in the atmosphere). Even if the fine lime did reach the target area, the quantities would be insignificant compared to an intentional Limeflo application through suspension. (this is applied with water as a carrier to ensure it reaches the target area).
[*FINE PARTICLE DYNAMICS: Fine particles between 0.1 and 0.5 mm diameter when caught by even a light wind are blown almost horizontal (generally between an angle of 7 to 12 degrees from the horizontal line) and can therefore travel long distances; particles around 20 microns and smaller will travel even further, being able to be suspended in the air [and often not coming down until intercepted by rainfall] (Foth, 1984).]
There is another hindrance to calcium release from granular lime in that unless it has been incorporated into the soil, much of the surface of the limestone is not in contact with soil or soil water. Also there is less efficient movement of the limestone and calcium below the soil surface.
The most pragmatic way to explain this is to think of a pepper corn coming into contact with your tongue, only the area that is in contact with the pepper corn is affected. However, if you were to sprinkle the same volume of pepper on your tongue in the form of “powder” your entire tongue would be affected.
How to improve granular lime effectiveness
The faster that calcium is released from granular lime, the better the response. This involves choosing a relatively high analysis (high calcium content) lime and making sure it is as fine as possible within price constraints. The rate of release is also largely related to soil biological activity, particularly earthworm activity. This is where Limeflo and granular lime can be used together strategically. A better result will be achieved with granular lime if the soil biological activity has been previously stimulated by the addition of Limeflo. The faster the calcium is released, the greater the chance of relatively high levels of calcium being in solution before this is balanced out by the levels of other cations; thus the greater the effect on soil organisms and clover nodulation.
When granular lime may be detrimental
In soils where the pH is already reasonably high, the level of calcium in soil solution is often lower than optimum; there may be high levels of potassium or magnesium responsible for much of the high pH. A boost in soil solution calcium levels will still be beneficial and is achieved with Limeflo without risking the effects of overliming with bulk lime. Similarly where copper levels are of concern due to high molybdenum availability, the aim should not be too high a long-term lift in pH as the problems would be exacerbated as molybdenum availability is increased at higher pH levels. Here the application of Limeflo is a useful tool and can be combined with the application of copper to fix any animal health problems at the same time.
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