Two minerals you can’t do without

Forage quality depends on the soil having the right mineral balance, and getting this right starts with calcium and magnesium.

If you’re a livestock farmer who incorporates cultivated pastures into your production system, forage quality can make all the difference to productivity and profitability.

Let me stress again that top quality forage will only be produced on soil that has a good mineral balance. The process of bringing soil to the desired mineral balance always starts with the two heavyweights – calcium and magnesium.

Dr William Albrecht, father of the Albrecht method, determined that calcium and magnesium should constitute 80% of all the positively charged minerals in the soil. If either of them are deficient or excessive it can radically reduce forage quality.

Should we ask which one is more important? In practice, all minerals are important and the trick in producing quality forage is to get them all at the desired level.

Many textbooks on soil mineral balancing refer to the law of the minimum, whereby the mineral that is most deficient will determine the level of productivity. There is also the law of the maximum: any mineral excess upsets the balance and suppresses production.

This is why applying too much lime can be disastrous. Remember that correcting excesses is most often far more problematic and costly than rectifying shortages.

The importance of calcium
Biological farming textbooks often refer to calcium as the “trucker” of nutrients into the plant. Simply put, an ample calcium supply is vital for the uptake of most other soil nutrients. This is one FAIRreason why calcium is a key factor in growing nutrient-dense forages.

The other major reason is that calcium is involved in many aspects of plant growth and development.
I once had a conversation with an industrial lime supplier in Gauteng, and was surprised to learn the extent to which lime is used in the manufacturing of a wide range of goods.

Few items in the CEO’s plush office hadn’t had lime involved somewhere in their production chain! This is how I understand calcium’s role in forage production – it’s multifunctional. Growing older and dealing with arthritis, I’ve also come to understand the vital role it plays in animal health.

It very easy to convey the importance of magnesium; there would be no life on earth without it! It’s an essential component of chlorophyll and enables sunlight, water and carbon dioxide to be processed into carbohydrates.

Magnesium’s role
It’s rare to find a magnesium deficiency in soil. Most often, an excess restricts forage quantity and quality, because soil high in magnesium is always hard. When it’s dry, it’s just about impossible to dig out a plant with a spade. Often, I’ve heard the loud ring of a good quality spade hitting rock-hard, high magnesium soil and have resorted to a pick.

When this soil is wet, it is very sticky, and when you walk across a recently worked land, this soil will add centimetres to the soles of your boots. Forget about growing good forage in soil high in magnesium. Next time we’ll look at how to correct magnesium excesses.

John Fair is a leading expert on pastures in South Africa, and founder and head of the SA Biofarm Institute in Harrismith. Contact him on 058 622 3585 or email [email protected]

Caption:
You can see the excess magnesium in these soils with the naked eye, and it’s sure to restrict forage production.
COURTESY OF JOHN FAIR