Beginner's Guide To Fertilisation

Achieving optimal yields is greatly dependent on providing crops with the right nutrition at the right time. Understanding the role of fertilisers and ensuring the correct application can make the difference between profit and loss. Lindi Botha reports

- Lindi Botha

Fertilisation is an exact science, and no two lands can be treated the same. It is therefore paramount that a farmer understands the different types of fertiliser, application levels, and timing of application before embarking on a fertiliser programme.

Crops continuously extract nutrients from the soil, and over time this can lead to severe depletion of soil fertility and land degradation. This in turn destroys the productive ‘capital’ of the soil and reduces the farm’s ability to produce a crop. If optimal yields cannot be achieved, it becomes uneconomical to continue buying and planting seed.

THE RIGHT MIX

For optimal fertiliser usage, the soil type, nutrient levels and yield potential of the crop and area must first be determined. Soil that is well looked after normally has the capacity to provide most nutrients needed, and shortages can be overcome by using carefully chosen fertilisers. It is wasteful to apply a nutrient if there is enough of it in the soil.

In general, macroelements are the nutrients most likely to be added to the soil. Micro- and secondary elements are also applied in small doses, as they play a crucial role in assisting plants to absorb macroelements.

The most important elements can be summarised as follows:

MACROELEMENTS

Nitrogen (N) improves overall crop quality. It helps a plant develop chlorophyll, the green pigment that enables the plant to absorb energy from sunlight to fuel its activities. Nitrogen is also absorbed from the soil and used by the plant to form proteins for growth. Simply put, N increases the number of plant cells, branches, leaves, seeds and fruit. A shortage of N results in yellow leaves and poor plant growth.