How do plants exchange ions with soil?

Blitz35

Well-Known Member
I've been reading quite a bit the past few days regarding cations and anions and how the process takes place in soil. I haven't found a specific article that shows how each specific element is taken up and what it gives in return when said element is used by the plant. Im also a bit confused when I keep reading that base cations (calcium, magnesium, potassium), neutralize the H+ ions that the plant releases? How do they neutralize the H+ ions when they themselves are cations (positively charged). I thought it would take a negatively charged anion to neutralize the H+ cation. For example, my understanding is that when the plant takes up an anion, like nitrates, it gives the soil back a negative H ion (hydroxide), which in turn will cancel out the H+ ions in the soil, but plants mostly give back H+ ions since they mostly feed on cations, which is why most soils turn acidic as the grow progresses, they use up all the base cations in the soil and eventually it gets concentrated with too many H+ ions, which is why cal-mag seems to fix so many issues. Its not that the plant 'needs' the calcium or magnesium, rather the soil needs base cations to neutralize the excess H+ ions, thus allowing the plant to continue its feeding process? Am in the ballpark with all this? If anyone can point me to an article that specifies in great detail how each element is treated by the plant, it would be greatly appreciated! Ive read dozens of posts this weekend, and feel I have an understanding, but im missing a few things to make complete sense of it :)
 

Blitz35

Well-Known Member
Thanks a lot for the 2 links! In general they say the same as I've read, but a couple added extras and it's explained differently..each little bit helps! Thanks again! :blsmoke:
 

NaturalFarmer

Well-Known Member
Plants DO need calcium and Magnesium and both in much higher amounts than most think which is why they are secondary nutrients and not Micro.



Calcium doesn't effect pH but carbonates do,


edit... however the displacement of hydrogen with calcium can but thats a base saturation thing.
 
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Blitz35

Well-Known Member
Plants DO need calcium and Magnesium and both in much higher amounts than most think which is why they are secondary nutrients and not Micro.



Calcium doesn't effect pH but carbonates do,


edit... however the displacement of hydrogen with calcium can but thats a base saturation thing.
I'll take a look at the two clips you attached. To say calcium doesn't affect ph, im not a pro, but I believe that's completely wrong! Calcium is the most used nutrient by the plant after npk, if there is low calcium in the soil, you are almost guaranteed to have a low ph..as calcium gets depleted, along with magnesium, the ph will drop as the most bondable element to the negative particles in soil then is H+, which also pushes potassium aside, and your left with nothing but H+ ions. Calcium and magnesium, being divalent, have 2 positive ions each, so each Mg or Ca ion can neutralize 2 H+ ions, thus raising the ph in soil. So in the end, calcium and magnesium greatly affect soil ph, even if not in a direct way.
 

NaturalFarmer

Well-Known Member
Does gypsum change you pH? Ill answer it for you..No Not very often.maybe if you have sodic soil and a few other instances but not the norm.
 
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Blitz35

Well-Known Member
Gypsum has a neutral ph, like lime? So I don't believe it should directly affect the ph of the soil.
 

Blitz35

Well-Known Member
My issue was with over fertilizing with nitrogen im guessing, the soil became too acidic and I noticed a calcium deficiency at the same time. This is all new to me, and it seems the more I read, the more complicated it all gets lol. Maybe im just gonna stick to a basic feed schedule and hope it works :)
 

Blitz35

Well-Known Member
How are you delivering the calcium? With a bicarbonate attached?
Im delivering the calcium via gh flora series lol. How its derived is a different question as that too seems very confusing. Like on their bottle of micro, it shows that the nitrogen is derived from ammonium nitrate. The only thing I kept reading is that nitrogen comes in EITHER an ammonium form or a nitrate form..so im thinking..wth is ammonium nitrate??? Its both together? lol. I think I went in over my head trying to research this..it may not even matter in the end..i'll find a basic nutrient feed and use that and not worry about calculations and the specifics of what and how the plant works :)
 

NaturalFarmer

Well-Known Member
I'll take a look at the two clips you attached. To say calcium doesn't affect ph, im not a pro, but I believe that's completely wrong! Calcium is the most used nutrient by the plant after npk, if there is low calcium in the soil, you are almost guaranteed to have a low ph..as calcium gets depleted, along with magnesium, the ph will drop as the most bondable element to the negative particles in soil then is H+, which also pushes potassium aside, and your left with nothing but H+ ions. Calcium and magnesium, being divalent, have 2 positive ions each, so each Mg or Ca ion can neutralize 2 H+ ions, thus raising the ph in soil. So in the end, calcium and magnesium greatly affect soil ph, even if not in a direct way.
This may help explain some.
 

Blitz35

Well-Known Member
This may help explain some.
Thanks for the link, it shows what I read, I understood that part, I was looking deeper at the actual ion exchange process. Most of the things I read refer to farming, or commercial grows, its hard to figure, how do I apply this to an indoor grow. How and at what rate for example, does nitrogen get leached from the soil? Does it get leached if one doesn't water to runoff, and nitrates stay within the roots reach? How long are the nutrients viable before they get bumped off their negative charge by an H+ ion? Most importantly, how can one know the exact composition of the soil, with regards to cal-mag, as the grow progresses, to insure the proper ratio remains balanced? It seems the more I read, the more questions I think of and I think this would take many months of research to fully understand lol :)
 
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