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Not many planters know this, but over-fertilizing your plants is actually more dangerous than under-fertilizing them. This means that if you put too much fertilizer, your plants will start to get sick from poisoning. The symptoms of fertilizer toxicity in oil palms can look very much like nutrient deficiency.

How does over-fertilization happen?

This is why effective fertilizer management is important. The main cause of fertilizer toxicity is poor fertilizer management. This is how it can happen:

• Pollution from nearby industrial sources, causing the soil to be flooded with heavy metal run-off
• Poorly trained workers or high turnover rate leading to erroneous methods of fertilizer application due to inexperience.
• Over-generalization of large plantations i.e. assuming that the whole plantation has the same fertilizer needs.
• Failing to do soil content evaluations regularly, leading to over-application of fertilizers the oil palms don’t need.
• Over-enthusiasm to push oil palms to increase production using fertilizers.

As such, there should be important steps taken so that over-fertilization does not occur and proper management is put in place.

Strategies for Fertilizer Management

You as a planter or plantation owner will have to adopt good production strategies to avoid fertilizer poisoning in your palms. For starters, conduct thorough soil assessments regularly.

Secondly, determine your output and growth targets. Once you determine your goals, you can then determine if there are areas in your plantation that are not meeting production targets. Fertilizers should be targeted at those locations, rather than applied at a standard level all throughout the plantation.

Finally, you should monitor those targeted areas to see if the fertilizers you applied are effective in raising production levels.  If your strategy is not working, then you’ll have to re-examine it to see what went wrong or how it can be improved.

How does Fertilizer Toxicity Look Like?

Usually, the three main plant nutrients, N (Nitrogen),P (Phosphorus)  and K (Potassium) will not cause toxicity. The ones causing toxicity would be the micronutrients which the oil palm needs in very small amounts. When they are present in higher amounts, this causes certain unhealthy symptoms to appear on the palms. Here are some of these signs to look out for:

Aluminium
Smaller roots which will impair root functions. When roots shrink, the oil palm will have difficulty absorbing Magnesium (Mg) and K from the ground, resulting in Mg and K deficiency.

Nickel

Nickel toxicity produces narrow, fishnet looking pattern of chlorosis along younger leaves.

Copper

Copper toxicity can be easily seen on leaves with the presence of small, uneven brown spots. These spots have depressed areas in the middle and will fuse together to form one large spot with yellow borders.

Boron

Boron toxicity can be seen at the tops of leaves, especially at the distal end and moving downwards in the form of chlorotic lines. These lines soon become necrotic and spread through the entire leaves.

A fine line between fertilizer deficiency and toxicity

Fertilizer deficiency can be corrected, but if you go beyond the recommended application rate, this can cause the oil palms to experience toxicity instead. Therefore, it’s crucial not to use fertilizers in an excessive manner.