Stone
Well-Known Member
So lets talk pH again! :rollhappy:
Last night I was reading a report on mineral analysis of the leaves of 35 species of various plants growing on both alkaline soils (pH 7.5-8.5) and acidic soils (pH 4.5-6).
NPK did not vary substantially and neither did Mg and S. So we can forget those. (Although it is highly likely that limestone plants get higher nitrate/ammonium ratios than silicate plants)
Surprisingly, Zn also did not vary too much either. Slightly higher in the acidic soils.
The concentrations are not as important here as the difference between the 2 samples.
As expected, Cu, B, and especially Fe and Mn were much higher in the acidic soil leaves and of course Ca was much higher in alkaline soil leaves.
Mo was not included but it is well known that Mo becomes much more available in the neutral to alkaline range. (very low at about pH5 or so).
And remember too that Mo is vital for nitrate use!
Results....Mean for Calcareous soils:
B 3.4 * Zn 1.08 * Cu 0.15 * Fe 1.2 * Mn 1.7 * Ca 374.
Results....Mean for Silicate soils:
B 4.3 * Zn 1.17 * Cu 0.18 * Fe 2.1 * Mn 5.7 * Ca 208.
Below is the availability of nutrients and various pH values.
This one is better. It has nice colours to guide us
We need to keep in mind also that in organic soils, Fe Cu and Zn are more tightly held than in mineral soils. (leaf mold and fern roots vs limestone rock face for example.)
After wondering how I could alter my fertilizers to better meet the needs of my Paphs (calcareous vs non calcareous) Adding higher concentrations of something or removing something else is next to impossible without a lab. Especially after looking at Xavier's analysis for wild mastersianum, emersonii etc. Iron was low and sometimes vanishingly low! So removing Fe from commercial fertilizers is a major interest!
In Xavier's cultivated plant tests , Mo became almost non-existent and nitrate levels went way up! Increasing Mo would not work well in the low pH anyway. You could reduce nitrate but that doesn't solve the Iron problem.....
Avoiding things like metal toxicity especially Iron and ensuring sufficient Mo and Ca for the limestone plants, and making sure non-limestone plants are getting enough Manganese etc.etc.
I decided the easiest way is simple pH adjustment. If we keep the water and fertilizer solutions for the calcareous Paphs around neutral and acidify the solutions and water for the remaining kinds to pH 5. We should go a long way to keeping things in the correct order. At pH 7 Mo is much more available and nitrate should be utilised better. Fe becomes almost out of reach (particularly in bark). At pH 5 Fe is readily available. (think rhododendron gardenia and citrus. They need low pH to get enough Iron. Now think about henissianum, callosum and sukhakulii. pH 7 would be too high for them I would think.
I have been acidifying all my tap water to from just over 7 to about 5.5 and giving that to everything.
My plan now is to change that to 7 (rain or tap) for the C/Paphs and 5 (or even lower) for the A/Paphs. I intend to use limestone dissolved in water to adjust up and lemon juice or some other acid to adjust down.
You can always add certain nutrients (like Mn or Fe or B or whatever) separately if you want later. But changing the availability to help avoid possible problems is what I'm talking about right now.
What do you think?
Last night I was reading a report on mineral analysis of the leaves of 35 species of various plants growing on both alkaline soils (pH 7.5-8.5) and acidic soils (pH 4.5-6).
NPK did not vary substantially and neither did Mg and S. So we can forget those. (Although it is highly likely that limestone plants get higher nitrate/ammonium ratios than silicate plants)
Surprisingly, Zn also did not vary too much either. Slightly higher in the acidic soils.
The concentrations are not as important here as the difference between the 2 samples.
As expected, Cu, B, and especially Fe and Mn were much higher in the acidic soil leaves and of course Ca was much higher in alkaline soil leaves.
Mo was not included but it is well known that Mo becomes much more available in the neutral to alkaline range. (very low at about pH5 or so).
And remember too that Mo is vital for nitrate use!
Results....Mean for Calcareous soils:
B 3.4 * Zn 1.08 * Cu 0.15 * Fe 1.2 * Mn 1.7 * Ca 374.
Results....Mean for Silicate soils:
B 4.3 * Zn 1.17 * Cu 0.18 * Fe 2.1 * Mn 5.7 * Ca 208.
Below is the availability of nutrients and various pH values.
This one is better. It has nice colours to guide us
We need to keep in mind also that in organic soils, Fe Cu and Zn are more tightly held than in mineral soils. (leaf mold and fern roots vs limestone rock face for example.)
After wondering how I could alter my fertilizers to better meet the needs of my Paphs (calcareous vs non calcareous) Adding higher concentrations of something or removing something else is next to impossible without a lab. Especially after looking at Xavier's analysis for wild mastersianum, emersonii etc. Iron was low and sometimes vanishingly low! So removing Fe from commercial fertilizers is a major interest!
In Xavier's cultivated plant tests , Mo became almost non-existent and nitrate levels went way up! Increasing Mo would not work well in the low pH anyway. You could reduce nitrate but that doesn't solve the Iron problem.....
Avoiding things like metal toxicity especially Iron and ensuring sufficient Mo and Ca for the limestone plants, and making sure non-limestone plants are getting enough Manganese etc.etc.
I decided the easiest way is simple pH adjustment. If we keep the water and fertilizer solutions for the calcareous Paphs around neutral and acidify the solutions and water for the remaining kinds to pH 5. We should go a long way to keeping things in the correct order. At pH 7 Mo is much more available and nitrate should be utilised better. Fe becomes almost out of reach (particularly in bark). At pH 5 Fe is readily available. (think rhododendron gardenia and citrus. They need low pH to get enough Iron. Now think about henissianum, callosum and sukhakulii. pH 7 would be too high for them I would think.
I have been acidifying all my tap water to from just over 7 to about 5.5 and giving that to everything.
My plan now is to change that to 7 (rain or tap) for the C/Paphs and 5 (or even lower) for the A/Paphs. I intend to use limestone dissolved in water to adjust up and lemon juice or some other acid to adjust down.
You can always add certain nutrients (like Mn or Fe or B or whatever) separately if you want later. But changing the availability to help avoid possible problems is what I'm talking about right now.
What do you think?
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