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The myth, of the high P myth?
- Thread starter epicseeds
- Start date
Top Thread bro! Respect! 
@ tester,
re coco, K, Ca, etc:
1. The CEC of coco (~10-30 meq/100g, IIRC) is quite a bit lower than peat (~80-150 meq/100g, IIRC), thus there should be no reason coco needs more Ca and Mg than peat in regards to CEC. The extra Ca and Mg needed for peat CEC sites is normally filled via liming agents such as dolomitic lime and calcidic lime. CEC sites are mostly filled (e.g., Percent Nutrient Saturation and Percent Base Saturation) by Ca, Mg and K (in that order). Also, Percent Nutrient Saturation of peat for Ca is higher than coco, IIRC. Lastly, the bulk density of coco is low, lower than peat (coco is normally ~0.08-0.10 g/cm^3), and the lower the bulk density the less well CEC sites hold onto cations and buffer pH; yet another reason the idea that CEC of coco needs extra Ca and Mg is flawed...
2. Much K is immediately available from coco, verified via testing with SME (Saturated Media Extract; using water). However, good coco brands flush coco to remove Na, which also removes K to varying degrees, due to poor bulk density of coco meaning CEC sites do not hold onto K and other cations well. That said, some K is immediately available from coco, see the first reference below for relevant testing via SME, etc.
3. The AEC of coco is very poor (due to low humic/humus content and no clay content), thus coco holds anions (like P) poorly; addition of humic acid and/or humic substances will increase both CEC and AEC. And bulk density can be increased by adding clay (ex., zeolite powder or calcined clays), which also increases CEC and AEC; bulk density can also be increased by compression.
Re: media testing:
1. It's not wise to use strong acids to extract elements from media because that is not representative of what happens in vivo. I.e., only weak acids are found in the rhziosphere and "soilless solution", re carbonic acid (from root and microbe respiration of Co2), root exudation of carboxylic acid, citric acid, citrate, oxalate, H+ protons, etc. This issue is very important for P, because P is mineralized (i.e., process of mineralization) from OM (organic matter) via weak acidic exudates from roots and microbes, as are other ions such as K and Mg (to a lessor degree).
For a better representation of plant available ions from mineralization of OM, using weak acid extract assays is preferred verses strong acid extract assays. Using carbonic acid media extract assays (i.e., Co2 extract assays) for ions that will be made plant available (via mineralization) by roots and microbes in a reasonable time frame, is far better than using strong acid extracts like is normally used for media assays. Here (link) is a great lab in Texas that offers Co2 extraction assay of media elements (K, Ca, Mg, Na), as well as strong acid extract assays. I use Co2 extraction assays for K, Ca, Ma and Na for a good representation of those elements that will be made plant available due to mineralization. And I use SME assay (with water) for a good representation of immediately available elements in the soilless solution (thin layer of water surrounding media particles).
Some refs:
"NUTRIENT ANALYSIS OF COIR FROM AGRO-COCO"
http://www.agrococo.com/Bethke/NUTRIENT_ANALYSIS_OF_AGROCOIR.pdf
"Understanding Plant Nutrition: Nutrient Sources: Media Cation Exchange Capacity"
http://www.greenhousegrower.com/magazine/?storyid=47
re coco, K, Ca, etc:
1. The CEC of coco (~10-30 meq/100g, IIRC) is quite a bit lower than peat (~80-150 meq/100g, IIRC), thus there should be no reason coco needs more Ca and Mg than peat in regards to CEC. The extra Ca and Mg needed for peat CEC sites is normally filled via liming agents such as dolomitic lime and calcidic lime. CEC sites are mostly filled (e.g., Percent Nutrient Saturation and Percent Base Saturation) by Ca, Mg and K (in that order). Also, Percent Nutrient Saturation of peat for Ca is higher than coco, IIRC. Lastly, the bulk density of coco is low, lower than peat (coco is normally ~0.08-0.10 g/cm^3), and the lower the bulk density the less well CEC sites hold onto cations and buffer pH; yet another reason the idea that CEC of coco needs extra Ca and Mg is flawed...
2. Much K is immediately available from coco, verified via testing with SME (Saturated Media Extract; using water). However, good coco brands flush coco to remove Na, which also removes K to varying degrees, due to poor bulk density of coco meaning CEC sites do not hold onto K and other cations well. That said, some K is immediately available from coco, see the first reference below for relevant testing via SME, etc.
3. The AEC of coco is very poor (due to low humic/humus content and no clay content), thus coco holds anions (like P) poorly; addition of humic acid and/or humic substances will increase both CEC and AEC. And bulk density can be increased by adding clay (ex., zeolite powder or calcined clays), which also increases CEC and AEC; bulk density can also be increased by compression.
Re: media testing:
1. It's not wise to use strong acids to extract elements from media because that is not representative of what happens in vivo. I.e., only weak acids are found in the rhziosphere and "soilless solution", re carbonic acid (from root and microbe respiration of Co2), root exudation of carboxylic acid, citric acid, citrate, oxalate, H+ protons, etc. This issue is very important for P, because P is mineralized (i.e., process of mineralization) from OM (organic matter) via weak acidic exudates from roots and microbes, as are other ions such as K and Mg (to a lessor degree).
For a better representation of plant available ions from mineralization of OM, using weak acid extract assays is preferred verses strong acid extract assays. Using carbonic acid media extract assays (i.e., Co2 extract assays) for ions that will be made plant available (via mineralization) by roots and microbes in a reasonable time frame, is far better than using strong acid extracts like is normally used for media assays. Here (link) is a great lab in Texas that offers Co2 extraction assay of media elements (K, Ca, Mg, Na), as well as strong acid extract assays. I use Co2 extraction assays for K, Ca, Ma and Na for a good representation of those elements that will be made plant available due to mineralization. And I use SME assay (with water) for a good representation of immediately available elements in the soilless solution (thin layer of water surrounding media particles).
Some refs:
"NUTRIENT ANALYSIS OF COIR FROM AGRO-COCO"
http://www.agrococo.com/Bethke/NUTRIENT_ANALYSIS_OF_AGROCOIR.pdf
"Understanding Plant Nutrition: Nutrient Sources: Media Cation Exchange Capacity"
http://www.greenhousegrower.com/magazine/?storyid=47
Edit #1:
Coco does have higher CEC than most low-humus (i.e., non-chernozem) soils. Non-chernozem soil has CEC of ~2-5 meq/100g, but chernozem soil can have CEC of ~5-20 meq/100g. I think the flawed claim that coco has high CEC comes from comparing coco CEC to non-chernozem soil CEC and CEC of perlite, etc. The CEC of humus (e.g., compost and vermicompost), vermiculite, peat, etc., are quite a bit higher than CEC of coco...
Edit #2:
I mention peat in both posts because peat is a soilless medium, just like coco, and both can be considered hydro culture via soilless media. Comparing peat to coco (and coco to vermiculite) is valid in terms of soilless culture using inorganic fertilizers.
Coco does have higher CEC than most low-humus (i.e., non-chernozem) soils. Non-chernozem soil has CEC of ~2-5 meq/100g, but chernozem soil can have CEC of ~5-20 meq/100g. I think the flawed claim that coco has high CEC comes from comparing coco CEC to non-chernozem soil CEC and CEC of perlite, etc. The CEC of humus (e.g., compost and vermicompost), vermiculite, peat, etc., are quite a bit higher than CEC of coco...
Edit #2:
I mention peat in both posts because peat is a soilless medium, just like coco, and both can be considered hydro culture via soilless media. Comparing peat to coco (and coco to vermiculite) is valid in terms of soilless culture using inorganic fertilizers.
Y
YosemiteSam
Mullray...thanks for the answer man. It contained a lot of good info.
My buddy at Custom Hydro is planning to get some powdered Si. When he does I will give it another real shot to see what happens. Do you have a recommend for ppm? As I recall with hydro store brands once I went above 25 ppm or so it started to seriously mess with my pH...then again maybe that is a good excuse to use a little more citric acid.
I will have to find a good source for fulvic but if I do I will give that a shot also. Do you have a ppm recommend?
And you are definitely right about indicas and high K. That is where I see the best results with this formula. It also works well on most hybrids although they do stretch some anyways. Still I think (would not swear to it just yet) that I end up with more bud sites even if they do not string together what you would call colas.
I am just starting to grow some pure sativas (TH's Haze, Thai and a Malawi). This formula does not keep them from stretching...but 3 weeks in bud development looks good and they are starting to get sticky so it probably isn't too bad. Not exactly sure what I would do different at this point...probably just finish the grow out like this so I have a baseline...then start tinkering (just another 11-13 weeks to go).
On the coco releasing K I do not doubt one bit unwashed coco does contain a lot of it (it probably contains all kinds of minerals due to where it grows) and that it will release it. But in the back of my mind I cannot help but think if these companies are washing out the Na they cannot help but wash out the K also. What solvent will dissolve Na but not K? Anyways I intend to keep incrementally pushing K til I find that point where it starts locking out divalent cations (and I assume Mg will be more susceptible than Ca simply because of how the two are transported through the plant).
Complete change of direction now...as far as true chelation goes it is my understanding that the ligand has to be able to attach itself in two or more spots on the metal to form a ring for it to be considered chelation. Does that mean +1 valence cations cannot be truly chelated? Like K for instance. Also does it mean to chelate a +3 cation you would need 3 moles of chelate vs 2 for divalent cations?
Plus I am sorry for taking this thread way off topic. Just got caught up in the good info. If a mod has a problem I could start a chelation thread...or maybe an everything but the kitchen sink thread.
edit...btw your little attachment contains some good info. It sure looks like adding some perlite to the coco would be a good idea. I cannot get past the dust and disposal of it though...if you can actually hate something in a bag I think I hate perlite.
My buddy at Custom Hydro is planning to get some powdered Si. When he does I will give it another real shot to see what happens. Do you have a recommend for ppm? As I recall with hydro store brands once I went above 25 ppm or so it started to seriously mess with my pH...then again maybe that is a good excuse to use a little more citric acid.
I will have to find a good source for fulvic but if I do I will give that a shot also. Do you have a ppm recommend?
And you are definitely right about indicas and high K. That is where I see the best results with this formula. It also works well on most hybrids although they do stretch some anyways. Still I think (would not swear to it just yet) that I end up with more bud sites even if they do not string together what you would call colas.
I am just starting to grow some pure sativas (TH's Haze, Thai and a Malawi). This formula does not keep them from stretching...but 3 weeks in bud development looks good and they are starting to get sticky so it probably isn't too bad. Not exactly sure what I would do different at this point...probably just finish the grow out like this so I have a baseline...then start tinkering (just another 11-13 weeks to go).
On the coco releasing K I do not doubt one bit unwashed coco does contain a lot of it (it probably contains all kinds of minerals due to where it grows) and that it will release it. But in the back of my mind I cannot help but think if these companies are washing out the Na they cannot help but wash out the K also. What solvent will dissolve Na but not K? Anyways I intend to keep incrementally pushing K til I find that point where it starts locking out divalent cations (and I assume Mg will be more susceptible than Ca simply because of how the two are transported through the plant).
Complete change of direction now...as far as true chelation goes it is my understanding that the ligand has to be able to attach itself in two or more spots on the metal to form a ring for it to be considered chelation. Does that mean +1 valence cations cannot be truly chelated? Like K for instance. Also does it mean to chelate a +3 cation you would need 3 moles of chelate vs 2 for divalent cations?
Plus I am sorry for taking this thread way off topic. Just got caught up in the good info. If a mod has a problem I could start a chelation thread...or maybe an everything but the kitchen sink thread.
edit...btw your little attachment contains some good info. It sure looks like adding some perlite to the coco would be a good idea. I cannot get past the dust and disposal of it though...if you can actually hate something in a bag I think I hate perlite.
Thanks for the answers Spurr and Mullray.
So with SME or the 1:1.5 with water methods the amount of K already in plant available forms.
After converting the mmol/l to ppm (mg/l):
1:1.5 with water extraction method (Mullray's post):
Method unknown (from the same post)
Method unknown
In Spurrs link (Agrocoir nutritional propereties) Table 1. shows:
The TOTAL NUTRIENT CONTENT (not just plant available) of different grade coirs. (converted from %dw to ppm)
SME (plant available) with the same coir
I could say that these differences in the level of K comes from the different testing methods.
I also assume that coir dust can play a big role in the amount of K at the first initial SME tests, because the finest grade coir had the highest amount of plant available K (162 ppm versus coarse coir's 112 ppm).
After the coir dust is gone, the K will stay in the fibres until they start to break down, which can be a long time for coir.
So with SME or the 1:1.5 with water methods the amount of K already in plant available forms.
After converting the mmol/l to ppm (mg/l):
1:1.5 with water extraction method (Mullray's post):
- 35.2 K
- 4 Ca
- 2.43 Mg
- 29.9 Na
- 49.7 Cl
Method unknown (from the same post)
- K 1068.6
- Ca 7216
- Mg 818.4
- Na 568.1
Method unknown
- 3700 K
- 119 Ca
- 104 Mg
- 2022 Na
- 3498 Cl
In Spurrs link (Agrocoir nutritional propereties) Table 1. shows:
The TOTAL NUTRIENT CONTENT (not just plant available) of different grade coirs. (converted from %dw to ppm)
- 18000 K
- 1400 Ca
- 1000 Mg
SME (plant available) with the same coir
- 130 K
- 4 Ca
- 8 Mg
I could say that these differences in the level of K comes from the different testing methods.
I also assume that coir dust can play a big role in the amount of K at the first initial SME tests, because the finest grade coir had the highest amount of plant available K (162 ppm versus coarse coir's 112 ppm).
After the coir dust is gone, the K will stay in the fibres until they start to break down, which can be a long time for coir.
All the scientific analysis of coco and peat is interesting.... I would like to see someone outyield straight coco with straight peat given all other variables were the same. Ie method, nutes and environmental conditions. Peat breaks down too fast is hydrophobic and it's harvest is not eco-friendly. Oh, and it compacts too tightly and in general is shit!
Wow, I just contributed to how far off topic this thread is LOL!
Wow, I just contributed to how far off topic this thread is LOL!
I have an idea:
Lets get this thread back on topic of phosphorus...even though I disagree with what my buddy Azeotrope posted about coco verses peat, I do agree this thread needs to get back on topic. If people want to discuss coco, or humic, another thread would be best IMO; just like another thread for foliar is best. I for one will not be posting anything more off topic than I already did.
Lets get this thread back on topic of phosphorus...even though I disagree with what my buddy Azeotrope posted about coco verses peat, I do agree this thread needs to get back on topic. If people want to discuss coco, or humic, another thread would be best IMO; just like another thread for foliar is best. I for one will not be posting anything more off topic than I already did.
Well I agree with spurr on getting back on topic. The sad thing is that from a purely technical perspective, I can't hang on the scientific end of this thread. I can only offer that I got off of the high P dosages years ago and found that nothing was lost and my plants have been extremely healthy on very moderate P levels. I do notice that pushing K seems to yield greater bennefit. To a point that is....
So, purely observational insight from me and a good dose of thanks for the educational and scientific offerings that you all were laying down. When the bickering is not present, it stimulates others to do more reading and research. Probably saves some folks some money on high P snake oil purchases.
So, purely observational insight from me and a good dose of thanks for the educational and scientific offerings that you all were laying down. When the bickering is not present, it stimulates others to do more reading and research. Probably saves some folks some money on high P snake oil purchases.
Y
YosemiteSam
Some observations based on personal experience with Sunshine Just Coir straight out the bag with no treatment whatsoever.
P in the 40-60 range seems to work best. I prefer the lower end because of the size of plants I grow. Smaller plants where some stretch might be preferred will probably like 60 better.
A K-Ca-Mg ratio of 4-2-1 seems good and allows the three to work together pretty well. I suspect (but have not tried) you could push the Ca a little bit without locking out the other two but if you push K or Mg much beyond that you risk locking out Ca...Ca being the least mobile of the 3 in the plant making it most susceptible to getting locked out.
Without foliar feeding Ca if you run N much above 120 you are going to risk tip burn from the plant growing faster than Ca can translocate to the growing tips (this will be highly influenced by environment and the amount of K you choose...but in my environment it is what I see). Burnt tips are not a good thing...it means cell membranes are comprised in all growing tips...including the roots.
Foliar feeding Ca (in the right form...I know Calcium 25 works and now I am trying Metalosate Calcium) gives you some insurance that you will get enough Ca to the growing tips and buds. You can do this on top of the 4-2-1 ratio without fear of locking out K or Mg. I started with a once every 4 weeks program...that works safely I will guarantee. I am now doing it more often but would not recommend that to anyone else at this point until I see what happens.
My next area to look at is going to be Boron nutrition. When my plants grow very quickly they tend to get slightly hollow stems. My current opinion is that Ca and B work synergistically in building cell wall integrity and that hollow stems are a lack of B in that combo. Again, I think this goes to cell wall integrity...I want to maintain it perfectly throughout the grow. I intend to add B slowly (there are toxicity issues when you go too far) and see if I cannot fix that problem and if fixing it leads to quantity or quality increases.
I will shut up now.
edit...I lied, do not use Phosphoric or Nitric acid as a pH down unless you account for the increases in P or N...they can add up very quickly and will be detrimental to your success. Citric acid is relatively cheap and is an excellent pH down, Sulfuric acid would be my second choice.
P in the 40-60 range seems to work best. I prefer the lower end because of the size of plants I grow. Smaller plants where some stretch might be preferred will probably like 60 better.
A K-Ca-Mg ratio of 4-2-1 seems good and allows the three to work together pretty well. I suspect (but have not tried) you could push the Ca a little bit without locking out the other two but if you push K or Mg much beyond that you risk locking out Ca...Ca being the least mobile of the 3 in the plant making it most susceptible to getting locked out.
Without foliar feeding Ca if you run N much above 120 you are going to risk tip burn from the plant growing faster than Ca can translocate to the growing tips (this will be highly influenced by environment and the amount of K you choose...but in my environment it is what I see). Burnt tips are not a good thing...it means cell membranes are comprised in all growing tips...including the roots.
Foliar feeding Ca (in the right form...I know Calcium 25 works and now I am trying Metalosate Calcium) gives you some insurance that you will get enough Ca to the growing tips and buds. You can do this on top of the 4-2-1 ratio without fear of locking out K or Mg. I started with a once every 4 weeks program...that works safely I will guarantee. I am now doing it more often but would not recommend that to anyone else at this point until I see what happens.
My next area to look at is going to be Boron nutrition. When my plants grow very quickly they tend to get slightly hollow stems. My current opinion is that Ca and B work synergistically in building cell wall integrity and that hollow stems are a lack of B in that combo. Again, I think this goes to cell wall integrity...I want to maintain it perfectly throughout the grow. I intend to add B slowly (there are toxicity issues when you go too far) and see if I cannot fix that problem and if fixing it leads to quantity or quality increases.
I will shut up now.
edit...I lied, do not use Phosphoric or Nitric acid as a pH down unless you account for the increases in P or N...they can add up very quickly and will be detrimental to your success. Citric acid is relatively cheap and is an excellent pH down, Sulfuric acid would be my second choice.
gregor_mendel
Active member
Yosemite
Where are you getting citric acid?
When I search I find only nutritional supplements.
I suppose I could use those, but don't want to spend the money to find out something in it is not water soluble.
Where are you getting citric acid?
When I search I find only nutritional supplements.
I suppose I could use those, but don't want to spend the money to find out something in it is not water soluble.
Y
YosemiteSam
I get it from Peaceful Valley Farms for like 5 bucks a pound..http://www.groworganic.com/ I currently use no more than 1 tbs per hundred gallons so it does not contribute much cost at all.
If you have someplace close that caters to home beer brewing they will carry it also.
I cannot imagine any citric acid you could find that is not water soluble.
If you have someplace close that caters to home beer brewing they will carry it also.
I cannot imagine any citric acid you could find that is not water soluble.
When growing in soil high doses of P kill the fungi in the soil or make it go dormant. These fungi are the very same microbes which supply the bulk of P to the plant. Never use ferts over 10 -10 -10 in soil or else you kill off your microherd.
I could be wrong, but I believe that correct Boron levels are key to bud set and flowering overall. I have noticed that it is a key component in the Dutch Master Potash+ 0-7-4-11 that I have used in the past. I recall reading-up on Boron quite a lot a couple of years back...
Y
YosemiteSam
I do not know the correct levels. I am either going to have to design an experiment to determine that or just sneak up on it over several grows. Have not determined the exact approach I am going to use just yet.
There are a lot of peach tree growers in this area. They swear by foliar Ca, Zn and B claiming it leads to more fruit sets...hopefully bud sites in my case. They go by quarts per acre which: a) is highly dependent on what is in their soil and b) is hard as fuck to convert to how much per gallon I should use.
Anyways...I am pretty sure some would definitely be useful and also certain too much is bad. I saw an actual study with bud sets on fir trees (who would have guessed). Up to a point the application of foliar Boron and Zinc made significant increases in bud set (95% confidence level) but beyond that and results started going the other way.
So right now I do not recommend anything (cause I really do not know). Once I have played around a little I will be happy to give a safe recommendation for everyone to start.
My Albion Plant Nutrition rep is recommending 2 oz of Ca and 1 of Zn and B per gallon (but they have no experience with marijuana and no interest in getting that experience)...but that scares the shit out of me.
There are a lot of peach tree growers in this area. They swear by foliar Ca, Zn and B claiming it leads to more fruit sets...hopefully bud sites in my case. They go by quarts per acre which: a) is highly dependent on what is in their soil and b) is hard as fuck to convert to how much per gallon I should use.
Anyways...I am pretty sure some would definitely be useful and also certain too much is bad. I saw an actual study with bud sets on fir trees (who would have guessed). Up to a point the application of foliar Boron and Zinc made significant increases in bud set (95% confidence level) but beyond that and results started going the other way.
So right now I do not recommend anything (cause I really do not know). Once I have played around a little I will be happy to give a safe recommendation for everyone to start.
My Albion Plant Nutrition rep is recommending 2 oz of Ca and 1 of Zn and B per gallon (but they have no experience with marijuana and no interest in getting that experience)...but that scares the shit out of me.
Boron and fulvic acid
Boron and fulvic acid
I know I wrote I wasn't going to post off topic again, but if this will help the thread get back on topic of P, and off boron, calcium, humic substances, etc., then I am happy to oblige:
0.25-0.5 ppm (up to 1 ppm max) boron should be a sufficient level for fertigation. Foliar spraying boron could be helpful because many species have poor movement of B via phloem, but very low level of B should be used if in foliar spray. It's easy to over apply B and cause toxicity. Considering cannabis seems to do OK without B in many hydro and soilless fertilizer mixes (e.g., Lucas formula, Rez/H3ad Coco, etc.), it's best to keep it below 1 ppm, max.
I have been working on a custom cannabis fert mix with all the normal elements plus B, Ni, Cl, Se and Si.
Refs:
"Symptoms of Deficiency in Essential Minerals"
Wade Berry, UCLA
A Companion to Plant Physiology, Fifth Edition
by Lincoln Taiz and Eduardo Zeiger
http://5e.plantphys.net/article.php?ch=t&id=289
"Boron Functions in Plants: Looking Beyond the Cell Wall"
Ildefonso Bonilla, Dale Blevins, and Luis Bolaños
A Companion to Plant Physiology, Fifth Edition
by Lincoln Taiz and Eduardo Zeiger
http://5e.plantphys.net/article.php?ch=e&id=403
"Effect of boron, copper, manganese, and zinc on the enzyme activity of tomato and alfalfa plants grown in the greenhouse"
L.F. Bailey and J.S. McHargue
Plant Physiol. 1944 January; 19(1): 105–116.
http://www.plantphysiol.org/cgi/reprint/19/1/105.pdf
"The Mineral Nutrition of Higher Plants"
David T. Clarkson
Ann. Rev. Plant Physiol 1980. 31:239-98
"Boron and its role in crop production"
Umesh C. Gupta
CRC Press, 1993
"A Review of Factors Affecting Plant Growth"
Marianne Ames, Graduate Fellow
Wayne S. Johnson, Assistant Professor
University of Nevada, Reno
"Water quality: Is it important for teh greenhouse grower?"
Penn State
http://horticulture.psu.edu/courses/hort450/topics/waterQuality.html
"Secondary and Micronutrients for Vegetables and Field Crops"
By M.L. Vitosh, D.D. Warncke and R.E. Lucas
Department of Crop and Soil Sciences
Michigan State University Extension
Extension Bulletin E-486, Revised August 1994
http://web1.msue.msu.edu/imp/modf1/05209709.html
"Understanding Plant Nutrients: Soil and applied boron (A2522)"
K.A. Kelling
University of Wisconsin System Board of Regents and University of Wisconsin-Extension, Cooperative Extension (1999); SR-07-99-.75M-25
http://www.soils.wisc.edu/extension/pubs/A2522.pdf
P.S. RE: effective application rate of fulvic acid; it's not a couple hundred ppm:
(this is something I wrote to a buddy yesterday)
Boron and fulvic acid
I know I wrote I wasn't going to post off topic again, but if this will help the thread get back on topic of P, and off boron, calcium, humic substances, etc., then I am happy to oblige:
0.25-0.5 ppm (up to 1 ppm max) boron should be a sufficient level for fertigation. Foliar spraying boron could be helpful because many species have poor movement of B via phloem, but very low level of B should be used if in foliar spray. It's easy to over apply B and cause toxicity. Considering cannabis seems to do OK without B in many hydro and soilless fertilizer mixes (e.g., Lucas formula, Rez/H3ad Coco, etc.), it's best to keep it below 1 ppm, max.
I have been working on a custom cannabis fert mix with all the normal elements plus B, Ni, Cl, Se and Si.
Refs:
"Symptoms of Deficiency in Essential Minerals"
Wade Berry, UCLA
A Companion to Plant Physiology, Fifth Edition
by Lincoln Taiz and Eduardo Zeiger
http://5e.plantphys.net/article.php?ch=t&id=289
"Boron Functions in Plants: Looking Beyond the Cell Wall"
Ildefonso Bonilla, Dale Blevins, and Luis Bolaños
A Companion to Plant Physiology, Fifth Edition
by Lincoln Taiz and Eduardo Zeiger
http://5e.plantphys.net/article.php?ch=e&id=403
"Effect of boron, copper, manganese, and zinc on the enzyme activity of tomato and alfalfa plants grown in the greenhouse"
L.F. Bailey and J.S. McHargue
Plant Physiol. 1944 January; 19(1): 105–116.
http://www.plantphysiol.org/cgi/reprint/19/1/105.pdf
"The Mineral Nutrition of Higher Plants"
David T. Clarkson
Ann. Rev. Plant Physiol 1980. 31:239-98
"Boron and its role in crop production"
Umesh C. Gupta
CRC Press, 1993
"A Review of Factors Affecting Plant Growth"
Marianne Ames, Graduate Fellow
Wayne S. Johnson, Assistant Professor
University of Nevada, Reno
"Water quality: Is it important for teh greenhouse grower?"
Penn State
http://horticulture.psu.edu/courses/hort450/topics/waterQuality.html
"Secondary and Micronutrients for Vegetables and Field Crops"
By M.L. Vitosh, D.D. Warncke and R.E. Lucas
Department of Crop and Soil Sciences
Michigan State University Extension
Extension Bulletin E-486, Revised August 1994
http://web1.msue.msu.edu/imp/modf1/05209709.html
"Understanding Plant Nutrients: Soil and applied boron (A2522)"
K.A. Kelling
University of Wisconsin System Board of Regents and University of Wisconsin-Extension, Cooperative Extension (1999); SR-07-99-.75M-25
http://www.soils.wisc.edu/extension/pubs/A2522.pdf
P.S. RE: effective application rate of fulvic acid; it's not a couple hundred ppm:
(this is something I wrote to a buddy yesterday)
The classical test method for FA content is the best option, for now, and is what most humic scientists use and is recommended by the leading academic group "International Humic Substances Society" (link). For info about various testing methods for FA content, applicable state laws, etc., see the two articles I uploaded about humic substances: "Humic substances in biological agriculture" (by Lawrence Mayhew) and "The real dirt on humic substances" (by Ryan Zadow from BioAg)
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YS said:
I have used ~25 ppm of Ablion Ca AA powder, as well as ~50 ppm (the vials come in 0.5 gram sizes). That worked well, but like I wrote, I need to look into the POD of the calcium chelate because if it's too high then applying it as foliar is probably not worth while if you don't spike RH and apply a high quality non-ionic surfactant.
From the website:
"Hydroponics: 1 gram mixed with 10 litres (2.2 gal) makes [edit: about] a 100 ppm solution."
- Thus, 0.1 gram per liter = ~100 ppm and that means 0.1 gram per gallon = ~26 ppm. I have used 0.1 gram per gallon and 0.25 gram per gallon with good results. Each vial holds 0.5 gram and the website suggests 0.5-1 gram per gallon for foliar; but that's too high ppm for foliar IMO...
That said, applying calcium nitrate works just fine. I am not sure why you like to claim Ca can't penetrate the lipophilic cuticle. The charge of the inorganic ion doesn't stop cations from entering the leaf [1][2][3]. There are many misconceptions and myths written about ionic and non-ionic penetration of leafs; but that is for the foliar thread I will start soon.
I would still very much like to read the references you have about your claim that amino acid chelated Ca 'tricks' the plant, etc.
[1] see the study I uploaded titled:
"Foliar Nutriton Using Inorganic Salts: Laws of Cuticular Penetration"
J. Schönherr
Proc. IS on Foliar Nutrition
Eds. M.Tagliavini et al.
Acta Hort. 594, ISHS 2002
[2] see the study I uploaded titled:
"Cuticular penetration of calcium salts: effect of humidity, anions, and adjuvants"
J. Schönherr
J. Plant Nutr. Soil Sci. (2001), 164, 225-231
[3] "Polar Paths of Diffusion across Plant Cuticles: New Evidence for an Old Hypothesis"
Lukas Schrebier
Annals of Botany 95: 1069–1073, 2005
