Why does a high concentration of potassium prevent the uptake of manganese by roots?

[prankster]

Roots take their nutrients from the soil. The soil is negatively charged and binds nutrient cations to hold them for roots, to actively uptake the preferred ion, depending on its growth stage. If these nutrients are not bound to the soil they get flushed away by water.

Interactions of charges are described by coulombs law and basically says that a stronger ionic bond is formed by a larger charge or a smaller distance between the opposite charges. Thats why pH is so important. The hydrogen cation is very small and easily binds to the soil. So other bigger cations get flushed away.

Another factor is concentration. A large concentration of a certain cation balances the binding equilibrium of all cations towards the cations that are present in a larger concentartion.

But Potassium has negative influence on the uptake of manganese. Why?

Potassium has an ionic radius which is a lot bigger than that of manganese. Manganese also has two carges (+2).

But then again. Potassium is present in a far larger concentration in general. In my case K:Mn= 1 : 0,06.

So is this negative influence of a high concentration K caused by this concentration balance. And why are other small cations not effected?

 

[Emilya Green]

Hi @prankster!

So is this caused by the balance of this concentration balance. And why are other small cations not effected?

They are... just not to the same degree that K is. Mulder did a lot of work to understand these reactions... check out his chart:

 

[prankster]

Hi @prankster!

They are... just not to the same degree that K is. Mulder did a lot of work to understand these reactions... check out his chart:

Thats a nice chart. Im gonna look for more on that Mulder stuff. Thanks

 

[bobrown14]

Roots take their nutrients from the soil. The soil is negatively charged and binds nutrient cations to hold them for roots, to actively uptake the preferred ion, depending on its growth stage. If these nutrients are not bound to the soil they get flushed away by water.

Interactions of charges are described by coulombs law and basically says that a stronger ionic bond is formed by a larger charge or a smaller distance between the opposite charges. Thats why pH is so important. The hydrogen cation is very small and easily binds to the soil. So other bigger cations get flushed away.

Another factor is concentration. A large concentration of a certain cation balances the binding equilibrium of all cations towards the cations that are present in a larger concentartion.

Are you sure you're sure??

You gotta few things mixed in there.

Read this - its a good explanation and this is why FLUSHING doesn't work. Glad you brought that up. Its a good point.

Soil Management

When talking cations its good to have context. Are we talking soil and I'm ASSuming yes since this is a grow forum?

 

[prankster]

Are you sure you're sure??

You gotta few things mixed in there.

Read this - its a good explanation and this is why FLUSHING doesn't work. Glad you brought that up. Its a good point.

Soil Management

When talking cations its good to have context. Are we talking soil and I'm ASSuming yes since this is a grow forum?

I dont know. When you add a solution with H+ it will get buffered by the buffercapacity of the soil. Which releases nutrient cations into the water because of this exchange and the nutrients drains away.

I believe this is also the way how roots release cations when they are eating them. By releasing a small amount of H+ and then getting them into a entrance hole. But maybe its a bit of the simple explanation. I dont know

But that is an interesting article which im first going to read before saying some stupid shit.

About the manganese and potassium. Its in Cervantes book on page 251 about potassium.

 

[bobrown14]

You're getting into chemistry and mixing in soil science.

Just for shits and giggles what are we growing and whats the medium?

 

[prankster]

You're getting into chemistry and mixing in soil science.

Just for shits and giggles what are we growing and whats the medium?

Coir with drippers. But this is just a general question about the science.

 

[bobrown14]

The reason I asked about medium is its different in soil than hydroponics.

The chemistry is the same but how its being done completely different.

In hydro everything is soluble not so in soil.