Question
Thank you Sir for your answer.

I live in Indonesia where the average temperature is 25-30 C all year round.

I am wondering whether there is another way round of getting the Chinese fertilizer to work on par with Kemira fertilizer. Based on my understanding, pardon me if I am mistaken, nitrate is easily leached but not ammonium nitrogen however all ammonium will eventually be converted into nitrates. In that case, would it help if I am to fertilize with Chinese NPK a few days or even weeks earlier to achieve the same effect as Kemira fertilizer? If so, what are the factors I need to take into consideration to estimate how early than usual I should fertilize my farm?

Thank you and your answers are highly appreciated.

Herman


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Followup To

Question -
Hi.
I have a question to ask with regards to NPK fertilizers. I have been using NPK 15-15-15 made by Kemira for the past few years for my farm with good results. Recently I tried to compare it to a cheaper Chinese NPK 15-15-15. Keeping every other plant treatments the same, I noticed several changes with the plants. The stems look much stronger and plant growth is faster with Kemira's NPK.

Then I sent the two samples of NPK to the lab to be checked for its Total Nitrogen, Nitrate Nitrogen content, Total Phosphate, water soluble Phosphate and Total Potassium. Chinese NPK results are the same as Kemira's except for the Nitrate content. Kemira has 2% Nitrate and the rest is ammonium nitrogen while Chinese NPK N content is all in ammonium form.

Could you explain to me why I see such difference for the same 15% N, 15% P, 15% K NPK fertilizer? Please tell me if you need further information to answer this question.
Thank you very much in advance.

Herman

Answer -
Most plants prefer nitrogen in nitrate form.

Plants take up most nitrogen in this form, but can also take up nitrogen in ammonical form. Ammonium nitrogen is typically converted to nitrate nitrogen in the soil by the microbes. This happens typically in warm soil, so it is faster in summer than in spring.

If your crop is a cool season crop (such as kale) you are much better of using nitrate nitrogen compared to ammonical nitrogen.

Plants which are planted in cool soil will - everything else being the same - grow faster with nitrate nitrogen as this nitrogen can be taken up by the plants easier in cool soil. This really applies to any crop (warm or cool) but is especially pronounced for cool season crops.

Also, nitrate nitrogen is known to create more compact plants with stronger stems compared to nitrogen from ammonium; although temperatures and light also play a very important role here; and so does the amount of fertilizer applied. In your case, 13.33% of the Kemira nitrogen is in nitrate form (2/15 x 100) which is significant enough to make a difference.

Nitrate leaches fastest from the soil (due to its chemical negative molecular structure) and therefore if you fertilize soil which gets excessive rains it is not recommended to use fertilizers with high percentage of nitrate nitrogen. Otherwise, plants can benefit from nitrate nitrogen and especially cool crops.

In warm soil, the conversion from ammonium to nitrate is relatively fast, and if you fertilize with 15-15-15 containing 2% nitrate and 13% ammonium nitrogen then my guess is that most of the fertilization occurs with nitrate; an ammonium only nitrogen fertilizer would result in plants taking up some in the ammonium form.

In other words, I think Kemira fertilizer is very good and it certainly seems to fit your crop type well based on your description. To make sure that the results noted where not just a single "off year" example, you could try to fertilize part of next year's crop with Kemira and rest with the Chinese fertilizer to judge the difference.

Answer
Both fertilizers are suitable. One has nitrogen partially in nitrate form which is preferred by most plants, but since your temperatures are rather high, the ammonium fertilizers should convert quickly.

I think you misunderstand my comment about leaching from soil. Nitrate will stay in the soil to be taken up by the roots. In situations where nitrate is not taken up immediately by the roots of the plants, the nitrate can leach out of the soil (and run into rivers, streams, or water sheads) before it can be used. This can lead to pollution and to loss of fertilizer (waste).

The same will happen with the ammonium fertilizer because it, too, is converted to nitrate rather quickly.

Therefore, it is better to apply in smaller doses more frequently rather than in large doses less frequently. However, I do not recommend fertilizing every few days.

Most crops should be fertilized on a monthly basis or less. You could apply the fertilizer half strength but every 14 days, but more often than that is really not necerssary. The frequent applications at half dosis is really only necerssary if you have excessive amount of rain falls at the same time.

If your soil is loam or clay, it will hold nutrients better than sandy soil which tends to leach nutrients faster. Therefore your soil type will also dictate which method is preferred.