How to lime and test your soil

Modern ways of testing soils are quicker and more affordable, ensuring more convenience for farmers. One of the parameters tested is soil pH.

A soil with low pH is said to be acidic, thus not good for crop cultivation due to lack of nutrients resulting from the acidity.

Soils with high alkalinity are also not good for productivity. Often, soil acidity is the most common phenomenon farmers face, thanks to the often used highly chemical fertilisers and agricultural inputs.

To correct this problem, experts may advice you to use of lime. However, despite the fact that lime corrects soil pH, there are factors that farmers ought to consider before its application.

Without strict adherence to these factors, soil acidity will not be effectively addressed and you could easily end up destroying your soil.

Consider the following factors before liming your soils to ensure improved productivity:

Test your soil pH

We all go to the hospital when we are sick and the normal procedure is for the doctor to carry out tests before treatment.

Similarly, before administering any correction to your soils, you MUST have the soil tested. You cannot lime your soil when you do not know its pH. Just like the doctors’ recommendations, you should apply lime to your soil according to recommendations by an expert after your soil test.

Blindly lime your soil without a test, and you might do it in excess.

Your type of soil is important

Lime is a chemical that reacts with the soil before correcting the pH. Different soil types will react differently to the liming.

Before liming your soil, check its texture on the test report. Clayey soils tend to consume more lime than loamy and sandy soils. The following are indices to which lime raises the pH in different soil types.

Clayey – 0.3

Loamy – 0.5

Sandy – 0.7

This means that to raise the pH of a farm with clayey soil, you will need more lime than in farms with loamy and sandy soils. It is, therefore, important to know the type of soil to get good results.

Choose the correct kind of lime

The type of lime you choose is very important. There are two main types of lime used in our soils.

Dolomitic lime, which has deposits of magnesium carbonate in it. Calcitic lime that has high levels of calcium carbonate.

A soil test enables you to know what is ideal for your soil. If test results indicate low pH, and low calcium deposits, you need to lime your soil with calicitic lime as it will also help increase calcium levels.

However, if your test results indicate low levels of pH and low magnesium deposits then, dolomitic lime would be better applied.

Understand value of the lime

Fertiliser bags will indicate their mineral composition on their labels, so will your bag of lime. The effective neutralizing value refers to the ability of a unit mass of lime to change soil pH. This depends on the chemical size, particle distribution and the solubility of lime.

As you purchase your lime, check on the bag. If it is indicated NV 100% then it has a full neutralizing power, If it is 50% then it neutralizes half way.

This means you need twice as much of this lime as that of NV100%.

For example, if your soil needs a 50kg bag of lime per acre to raise your pH from 6.3 to 6.5, if you purchase that one bag with NV 100%, that will be enough. But if you purchase the one with NV 50%, it will neutralize halfway. For the right effect you will, therefore, have to use two bags.

Timing is everything!

As the saying goes, a stitch in time saves nine. Carry out a soil test early, at least one month before planting. Liming is a chemical process. Therefore, it should be given enough time to work and improve the soil.

Correct timing is vital when amending the soil for maximum productivity. Carrying out a soil test will guide you on the exact amount of lime you need, the rate of application and timing of application.

In case you don’t understand the recommendations on your soil analysis report, seek expert advice to get value for your money and avoid making mistakes.

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