“Three changes are constantly taking place in the soil:

First, acidity is tending to develop.

Second, humus – the soils content of decomposed organic matter, is being used up.

Third, certain elements essential to plant growth are being removed by the harvest crops or removed in other ways.

These statements are not opinions. They are established facts recorded and proved by thousands of experiments. Neither the fertiliser nor the anti-fertiliser school of thought will quarrel about them; the quarrelling begins only when we start talking about methods of compensation for these changes . . . . . . . If we are to go on producing enough food for ourselves from the soil, we must continually correct nature’s acid tendency, which conflicts with our necessities. The actual fact that soils do get acid is easy enough to determine.”
Dr. Hopkins (Rothamstead)

Because limestone is a conditioner of the soil, it has very important role to play in each one of the three changes mentioned above. It is used to neutralise the acidity produced, it encourages humus to be replenished and finally, it is a good source of calcium, carbon and oxygen.

Since 1932, Hatuma has manufactured high quality limestone to combat the development of acidity within the soil. This acidity has always been there, it is building as you read this and the detrimental effect it has on the farms performance can be immense.

But many farmers who are aware of this ongoing need have overcome the associated problems connected with this natural occurrence by applying light dressings of Hatuma limestone.

Lime is a soil conditioner or the oil in the engine. Its role is not initially associated with growing grass, but instead starts only when recycling the wastage products from growing grass and animal production begins. Without the right pH environment and supply of energy, the cycle is broken. This brings not only consequences in the balance of the soil and quality of pasture, but for the environment as well.

When the composting organisms recycle the tonnes of dead grass, manure and urine, an acid residue gets produced. In high rainfall areas this is a process that can be slightly subdued by the extra water diluting the acid and cleansing the soil, but for most regions the acidity can become a problem, not only to the soil life and humus, but to the pasture growth and ultimately the stock and their health.

The most important essence of the grassland soil and its ability to continue being fertile is the pH associated within the top litter layer (t o a depth of 10-12mm). Sir Albert Howard found that the optimum range for the pH to allow the microbes in the soil to thrive was a neutral pH environment; one that encourages the healthy diversity of micro-organisms, the recycling of the litter, and the resultant rapid humus manufacturing. The litter layer is the ‘front line’ of the soil, an area where most of the action takes place and the beginning of the recycling stage starts. It is in this delicate area that the dead grass and manure land, and are beginning to be broken down and recycled by the soil life. But these crucial organisms, which include everything from countless microbes to earthworms, cannot survive in an acidic environment. Nor can they be expected to work without adequate carbon for their energy. Therefore, when they are forced into living in this sort of environment, they become too slow to break down the litter layer, and consequently the recycling process shuts down (have you seen any cow pats that can be thrown like a frisbee lately?).

This acidity throttles the humus makers that do not like acid of any kind, and creates toxic soil conditions with the minerals in the soil in the litter layer. This can inhibit the plant from growing efficiently. An acidic litter layer in an agricultural soil environment can also be unhygienic as acid tolerant microbes, such as the facial eczema fungi and TB bacteria are free to exist without the overwhelming competition from the humus making microbes.

But like everything in nature, there needs to be a balance. More often than not when the decision is made to apply lime, the traditional process of getting a soil test first shows the only way to counteract the acidity is to apply 1 tonne of lime per hectare to raise the pH by 0.1. Unfortunately though this results in a large application (typically anywhere between 1-5 tonne a hectare, or in some cases even more). It can also mean liming becomes a very expensive exercise.

The traditional soil test is calculated to find out the amount of limestone required to raise the soil’s pH to the desired level to a soil depth of 75mm. However, in a grassland situation, any applied limestone will only achieve the desired pH from 2 – 12mm per year. In some circumstances it takes many years to correct the pH to the full 75mm of soil depth.