# How fast is potassium absorbed by plants ?



## kekon (Aug 1, 2005)

I'm going te carry out an experiment to get to know how fast the potassium is absorbed by plants in the course of 24 hours. Water samples will be examined in laboratory. Maybe someone of you has any experience concerning the problem ? Some say, it is 10..15 ppm per week, others say it is about 4 ppm. I assume there are proper levels of other nutrients, CO2 and good lighting about 0,7W/L.


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## BryceM (Nov 6, 2005)

Interesting. Please share a description of your methods. The uptake rate will be dependent on an enormous range of variables. It will be a hard question to answer in general terms but much easier to describe in a controlled setting.

You'll need to account for lighting, CO2 levels, other nutrients (if anything is limitting K uptake will be slowed), plant species, plant density, temperature, CO2 levels. Most people tend to ignore K since it is difficult to test for. For most 'high-tech' tanks it is assumed that K is present in abundance. This is may or may not be true. Keep us informed.


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## niko (Jan 28, 2004)

I'd like to see the N and P uptake during the period in which you will measure the K uptake.

Also if possible at al the Fe, Ca, and Mg uptake.

--Nikolay


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## Edward (May 25, 2004)

Hi
We have to take into consideration the equation between K, N and P because they are all mobile elements and therefore very flexible in individual uptake rates and also dependent on each other at the same time. The actual K uptake rate result of x ppm per week does not help much. The most valuable information would be what the NO3, PO4 and K ratio is per week at daily dosing practice. 

Edward


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## Faruk Gençöz (Nov 4, 2005)

When the water is tested at time1 and time2, the difference may not show the amount that the plants actually used. If the question is to understand the uptake of the plants then the plant mass should be analyzed. To do that in a controlled conditions many parallel tanks should be prepared. On the other hand we are hobbyists not biologists so testing the water precisely would be more practical and humanistic. In this case it should be considered the eco system in the water. So I would consider what guaiac_boy, Nikolay and Edward says.

That been said, any level and type of experiments would help us and stimulate the new chain of experiments. Please keep us informed about the every detail of your experiment. Write a note at the entrance of the room:Warning! APC Community Experimentation Lab


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## kekon (Aug 1, 2005)

Well, I realize that the measurements will not be accurate and not very reliable. Unfortunately, I got into new troubles  First, I dosed too much KNO3 and probably i had K excess - 27,2 ppm. It ended up with expected 10 ppm NO3 level but also, I got twisted leafs on Umbrosum and Alternatera, the total growth was much slower. However, many of thread-like algae disappeared. (I wrote about the issue in "KNO3 - Too much potassium") thread. I did 2 water changes: on first day 40% and on second day - 50% to get rid of K excess. Then, I stared dosing much smaller amounts of KNO3 in order not to obtain too much K again. But I noticed problems again - after 4 days of dosing smaller KNO3 doses NO3 is about 2ppm. PO4 - 0.5ppm. More thread-like algae appeared again. Plants grow faster, but Umrosum for instance, is still "sick" (it grows very slow). Hygropila difformis leafs are very light-green. It also concerns some sagitaria lefas - they're very light-green. Now, I suspect there is N deficency. On the whole I'm very confused... I thought about taking K from KNO3 and from Ca(NO3)2 but I see many people use only KNO3 and have very good results.


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## plantbrain (Jan 23, 2004)

edit


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