Choose the best method to apply fertiliser

October 2025

KOBUS VAN ZYL, SENIOR AGRICULTURIST, OMNIA NUTRIOLOGY® AND PIETMAN BOTHA, INDEPENDENT AGRICULTURAL CONSULTANT

THE YEAR IS SPEEDING TO AN END, AND FARMERS MUST MAKE SURE THAT EVERYTHING IS DONE TO MAXIMISE THEIR CROP YIELD. IT IS IMPORTANT TO MANAGE THE CROP ACCORDING TO THE FIRST PRODUCTION PLAN – ESPECIALLY THE FERTILISATION AND CHEMICAL PROGRAMMES. THESE PLANS MUST CONSTANTLY BE EVALUATED AND ANY NECESSARY CHANGES SHOULD BE MADE.

Production conditions play a significant role in determining the best method for applying fertiliser. Soils differ in fertility status. Sandy soils, for example, typically have lower fertility levels than soils with more clay. Certain soils have specific clay minerals and chemical properties that can retain applied nutrients, making them less accessible to plants. These are usually soils with a high clay content. The soil moisture and temperature also play a significant role in root growth and will determine whether plants can absorb nutrients efficiently.

The most important principle to consider is that the plant nutrients applied should be as easily absorbed by the plants as possible. The closer the nutrients are to the roots, the better the plants can absorb them.

There are two ways to apply the extra fertiliser, namely banding and broadcasting (scattering). With banding, the fertiliser is placed close to the plant by using a cultivator equipped with fertiliser bins. Broadcasting is done with a spreader where the fertiliser is scattered over the total area. With banding the fertiliser is concentrated near the plants, while this is not the case with broadcasting.

Table 1 shows the effect that the method of application (banding/broadcasting) will have on the uptake of specific nutrients. The type of fertiliser and application rate will also be determining factors. According to Table 1, phosphate (P) and potassium (K) are less suitable for broadcasting.

The main reason for this is that these two elements are mainly absorbed through diffusion. This means the fertiliser moves from the fertiliser band into the root due to the concentration difference. A high concentration in the band is essential for the uptake of phosphate and potassium. Certain soils can also bind phosphate and potassium. In these soils, banding will also be a better application method.

On well-developed soils with higher fertility, banding will have a smaller impact than on sandy soils. Micro-elements such as zinc, manganese, copper, iron, boron and molybdenum will also be better absorbed in a band. Be careful to apply micro-elements in quantities that are toxic to the plants.

Graph 1 shows the yield response of maize at two row widths (1,5 m and 0,75 m), where fertiliser was applied using banding and broadcasting. The differences in the examples are significant and confirm the importance of applying plant nutrients as close as possible to the plant roots for fast and effective uptake. In both examples, the same product was used at the same application rate. Only the application method differed.

In this case, the farmer received much better value for money by using banding rather than broadcasting. Most grain farmers use both banding and broadcasting as fertiliser application methods. Ensure that the application action supports effective nutrient uptake. If this is not the case, the application method should be adjusted for maximum efficiency.

Fertiliser that is broadcasted after emergence depends on the rainfall to ensure the nutrient uptake, while fertiliser through banding is already in the soil, where more moisture is available for absorption.

Graph 2 shows the yield response of soybeans to fertiliser through banding and broadcasting, using the same product at the same application rate. Just like with maize, the yield difference is significant. The row spacing used for the soybeans was 0,86 m.

It is not only the differences in the yield that are significant between banding and broadcasting. Satellite image data also clearly shows the differences, as indicated in Figure 1. The section on the left side of the photo had banding and is growing much stronger than the section on the right side, where broadcasting was used. The planting date and fertilisation were the same for both application methods.

All the examples indicate that plants respond better to a higher concentration of plant nutrients. In the fertiliser band, this concentration can be artificially created. Therefore, wide-ranging broadcasting of fertiliser cannot compete with banding on a concentration basis. 

To achieve the maximum yield, ensure that high-quality fertiliser is used at the correct application rate and with the best possible application method. 

Publication: October 2025

Section: Pula/Imvula