Development and Harvest Yields of Greenhouse Tomatoes in Six Orgnaic Growing Systems

Heres some more work of Bills if anyone is interested.

http://www.staugorchidsociety.org/culturewater.htm

Its a nice series of articles, some of which is repeated in the yearly series I mentioned before. Matching your fertilizer to your water is a pretty smart thing. Its something I never thought about before reading those articles.

Ive got a question regarding the uptake of Nitrate Nitrogen. In one of Bills articles he states:

In contrast, uptake of nitrate nitrogen increases substrate-pH because OH- or HCO3- (bases) are secreted by plant roots in order to balance nitrate uptake.

In the article you linked two other authors state:

When nitrate (or other negative anions) is absorbed, the roots balance the negative charge by absorbing H+.

Sooo which is it? Im confused.

The article that secondtry linked to above is the most recent from anyone on substrate pH.

Bill Argo and Paul Fisher literally wrote the book on the subject of pH management for container grown crops. No kidding, that's the title.

This is very good set of articles on the same subject: substrate pH, water, acids:

Understanding Water Quality part 1

Understanding Water Quality: Part Two

Argo's four part series is hosted by an Orchid society website.

Originally printed in 2003 in the Journal of the International Phalaenopsis Alliance, Vol. 12 (4).

Part 1 Intro
Part 2 Water Quality
Part 3 Fertilizers
Part 4 Substrates
Part 5 Choosing the Best Fertilizers

http://www.staugorchidsociety.org/culturewater.htm

This one by Paul Nelson, William Fonteno and Doug Bailey is excellent too:

Substrate pH and Water Quality

edit: Dave Coulier's post went up as I was working on mine, but I'm not going to change mine. The articles are that valuable.

Hey DC,

Here is edited copy of my quick and basic critique of the work by Argo and Fisher:



----------------------------------------------

Ok,

I ate a burrito and got some energy, read that work by Bill Argo and Paul Fisher:

Understanding Plant Nutrition: Nutrient Sources: Media Cation Exchange Capacity
In a year-long series, Argo and Fisher take a microscope to the details that can help growers make informed decisions on nutrients
By Bill Argo and Paul Fisher
February 2008
http://www.greenhousegrower.com/magazine/?storyid=47


Here are my thoughts as to what makes their finding not all that applicable to our efforts, i.e., organic microbiological horticulture. I will quote from their work and then offer my critique/thoughts, I will offer a summation at the end, let me know if you agree or disagree. Thanks.

Research has shown that the CEC of soilless media has little effect on resisting change in pH, or in supplying nutrients to the crop.

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The assumption by the researchers seems to be one will not apply additional nutrients. However, when growing cannabis we do apply additional fertilizers, that is why I say CEC has not been that important in the first place; it is not depended upon. And for media pHw we adjust pH of water/fertilizer so ions should be absorbed by roots while in water filled pores of media, not from CEC. If we didn't adjust pH of drench solution and didn't apply additional fertilizers then the authors findings would have more of an impact on us.

Hydrated lime was used as the lime source to increase the initial pH to about 6 in all media because it reacts quickly and completely and did not influence long-term pH management.

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Hydrated lime is not used in soilless media because it's easy to make the media phototoxic. Soilless media uses dolomitic lime and calcidic lime, both raise pHw more slowly but offer pHw stabilization for a long time (years) due to microbial mineralization and chemical interactions; some is used and some is replaced. Micronzied lime is best. If the researches used D. or C. lime the drop in pHw would not have been realized, there would be flux, but not such an intense drop.

Pro-mix and Sunshin mix use D.lime, not H.lime.

When an acidic fertilizer solution was applied to the impatiens grown in the different media, pH of the rockwool medium tended to be higher than for the other media. In all media, however, the pH dropped very quickly to a low of about 4 (Figure 2) regardless of the CEC of the media.

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See my previous comments about acidic N (ammonium) and how it does not lower pH in organic microbiological horticulture.

When shoot-tissue calcium was tested after four, eight, 12 or 17 weeks of growth, there was little difference between plants grown in the media with low CEC (rockwool perlite) or relatively high CEC (consumer grade peat/perlite). The media-CEC therefore did not act as a buffer to nutrient levels available for plant uptake.

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This is mitigated with different media as the CEC should have a grater effect depending upon BD, amongst other issues (see below). It's like I wrote, to mitigate the issues of "effective CEC" raise the BD of low BD media with amendments with decent levels of BD (compost, EWC, pumice, etc) and CEC (zeolite, compost).

The conclusion of these and other experiments was that CEC from peat has little or no effect on either pH management or calcium and magnesium management in container grown crops.

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That is true, and yet fortunately for us, not applicable to our situations as I tried to describe above, re: ammonium in regards to pHw and CEC in regards to BD (bulk density).

Secondary components (used at less than 40 percent of the total volume) for container media have little effect on buffering because they either have almost no CEC (perlite, polystyrene, rockwool, sand) or have such a low bulk density that its effect is minimal (vermiculite).

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This is why I suggest using good compost and/or good vermicast as amendments, to increase CEC and BD while offering all kinds of other benefits not provided from the amendments listed by the researchers. My mix is 7 parts APBF screened to 2-4mm; 1.5 parts peat screened from 2-4 mm; 0.5 part compost; 0.5 part vermicast; 0.5 part pyrolyzed rice hulls and 4-6% zeolite powder (by dry weight) and 4-6% azmoite; the BD should be 0.175-0.2.25 g/cm^3 (should be close to that of typical soil) and CEC should be > 70 meq/liter.

Calcined clay is an exception because it has a fairly high bulk density (about ½ that of the typical field soil) and CEC. But because of cost, calcined clay is typically added to container media at 5 percent or less of the total volume. Although calcined clay may affect buffering, the combination of lower bulk density and much lower incorporation rate means that its effect is limited.

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An example of this is Axis regular screen over 2mm screen. I have used it at 15% vol/vol in a peat mix and some vermiculite. Had great results. But if I add zeolite and compost the media should be high CEC and the BD should be close to that of typical soil. Using zeolite and compost with a peat/perlite/verm mix (i.e. Pro-Mix or SunShine mix) should provide the CEC you learned about, not that referenced to in the work by Argo and Fisher 2008.

CEC can be increased when a field soil is added to a container medium, which increases buffering of pH and nutrient levels because the medium has a high bulk density (weight). However, because of problems obtaining consistent and uncontaminated field soil, and the problems for freight and retail from having a heavy soil, most growers are no longer using soil in container media.

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This is an example of what I mean by using compost/vermicast and zeolite; but here the researchers are using soil as an example. My suggestion will offer much grater results than the authors suggestion of soil...

Conclusion

In contrast to field soils, CEC of soilless media has little effect on resisting change in pH or in supplying calcium or magnesium to a crop. However, buffering does exist in soilless root media. In the next articles we explain how limestone can be used to buffer pH, calcium and magnesium.

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The reason the claim CEC of soilless media has "little effect" is the BD of soilless media (e.g., peat and coir) is low, as is the CEC of the "secondary components" (e.g., perlite and verm). If one mixes a peat-lite mix (e.g. Pro-Mix) with compost/verimast/zeolite the CEC will resist pHw changes and act as a reserve "pool" of Ca and Mg for the roots and microbes, along with other cations.

To my understanding the work by Argo and Fisher (2008) does not apply to our soillless mixes and traditional knowledge about CEC is still perfectly valid. Note that if using vanilla Pro-mix or SunShine mix or LC mix (i.e. media based on Cornell U., "peat-lite mix") all of the authors findings are valid, save the pHw info because those medias don't use hydrated lime; and the fact the lime will increase the CEC over a longer period of time.

I also do not think water will flush ions from CEC in media I have described, can you show my why you think so? Or let me say I don't think water will flush ions as easily as shown by Argo and Fisher due to the use of D. and/or C. lime, not H. lime. To flush ions of acidic fertilizers use of alkaline solution is most effective AFAIK.

Please let me know what you think and if you see errors in my reasoning. All the best.
--------------------------------------

Damn thats alot to digest. I am gonna get some food, and relax. Then Ill read it all again later, but it all made good sense.

Im not sure why you think that I said, "You can flush ions from CEC". Could you quote me, so I know what you're talking about there .

I do agree though that Hydrated lime is well poop. D lime has a much greater affect on ph long term, cec, nutrient availability. In one of his articles he discusses how residual lime after a ph equilibrium is reached that has the greatest impact.

typo:

I wrote nitrate is a cation, and it's an anion, and I wrote ammonium is a anion but it's a cation. My bad.

Hey

Dave Coulier said:

Im not sure why you think that I said, "You can flush ions from CEC". Could you quote me, so I know what you're talking about there .

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I don't follow. I think that was in reference to the person who I was sending this to as an email originally.

I do agree though that Hydrated lime is well poop. D lime has a much greater affect on ph long term, cec, nutrient availability. In one of his articles he discusses how residual lime after a ph equilibrium is reached that has the greatest impact.

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Thanks.

Oh alright then. I thought you were directly speaking to me at the end of that big post. Duh

I wrote one of the authors of this article and asked him to help clear up my confusion regarding Hydrogen Ions being absorbed along with Nitrate Nitrogen and bases being exuded by plants when they uptake NN. Heres what he wrote back:

Hello XXX,

I can understand your confusion. Both secretion of OH- and absorption of H+ have been described as the process plants used to balance the negative charge taken on by the plant when NO3- enters the root.

If OH- is secreted by the root it combines with H+ in the soil solution to make H2O. Negative in and negative out. H+ in the soil solution therefore decreases and the pH increases.

If H+ enters the root with NO3- the plant still remains electrochemically neutral. The H+ is removed from the soil solution and pH increases.

With HCO3- secretion the following reaction takes place HCO3- + H+ = H2O + CO2. Again H+ is consumed and the pH of the soil solution increases.

Essentially, these three processes are all the same in respect to soil pH and the electrochemical charge of the plant.

I hope this has helps clear up your confusion.

Matt

sorry to butt in - secondtry or anyone, could you tell me how porosity, etc... change when media are fully colonized by roots like cannabis has? I know the medium itself doesn't change, but what if you take the whole system as an aggregate, roots and all? The values are different from empty media, no? Is the difference between the two always the same?

Dave Coulier said:

I wrote one of the authors of this article and asked him to help clear up my confusion regarding Hydrogen Ions being absorbed along with Nitrate Nitrogen and bases being exuded by plants when they uptake NN. Heres what he wrote back:

Hello XXX,

I can understand your confusion. Both secretion of OH- and absorption of H+ have been described as the process plants used to balance the negative charge taken on by the plant when NO3- enters the root.

If OH- is secreted by the root it combines with H+ in the soil solution to make H2O. Negative in and negative out. H+ in the soil solution therefore decreases and the pH increases.

If H+ enters the root with NO3- the plant still remains electrochemically neutral. The H+ is removed from the soil solution and pH increases.

With HCO3- secretion the following reaction takes place HCO3- + H+ = H2O + CO2. Again H+ is consumed and the pH of the soil solution increases.

Essentially, these three processes are all the same in respect to soil pH and the electrochemical charge of the plant.

I hope this has helps clear up your confusion.

Matt

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Great info thanks!

I would also like to read this persons thoughts about ammonium increasing pH in organic microbiological horticulture (or at least not lowering pH). Would you mind shooting him an email about that? (see page 3, paragraph 3 and 4 of the starting paper to this thread).

Also, will you ask him to clear something up for me: Which method to find pH of media is ideal or most common:

1) The PourTru method tho find media pH (i.e., pH of media water = pHw):
http://www.ces.ncsu.edu/depts/hort/floriculture/crop/crop_PTS.htm


2) Or the methods suggested by Cornell U., to find pHw by drying media sample (option A below):
http://compost.css.cornell.edu/monitor/monitorph.html


(note: I don't suggest the use of pH paper, ever.)

Compost Extractions
Using a calibrated meter or pH paper, you can measure pH in a compost extract made by mixing compost with distilled water. It is important to be consistent in the ratio of compost to water and to account for the initial moisture content of the compost, but there is no universally accepted protocol specifying these procedures.




A.) One approach is to read the pH in oven-dried samples that have been reconstituted with distilled water.

1.) Spread compost in a thin layer in a pan, and dry for 24 hours in a 105-110°C oven.

2.) Weigh or measure 5 g samples of oved-dried compost into small containers.

3.)Add 25 ml distilled water to each sample.

4.) Mix thoroughly for 5 seconds then let stand for 10 minutes.

5.) Read the pH with a calibrated meter or with pH paper and record as compost pH in water, or pHw.
​

B.) An alternative is to measure pH in samples that have not been dried. In this case, the amount of water that you add will need to vary to compensate for the varying moisture content of the compost. You will still need to dry some of the compost in order to measure moisture content, but you can take the pH readings on samples that haven't been altered by drying.


1. Calculate the % moisture of your compost:

a) Weigh a small container.

b) Weigh 10 g of compost into the container.

c) Dry the sample for 24 hours in a 105-110°C oven, or for 5 minutes in a microwave oven. If you use a microwave oven, place a beaker containing 100 ml of water in the oven during the drying to protect the oven's magnetron.

d) Reweigh the sample, subtract the weight of the container, and determine the moisture content using the following equation:​

M = ((Ww-Wd)/Ww) x 100
​

in which:​

M = moisture content (%) of compost sample

WW = wet weight of the sample, and

Wd = weight of the sample after drying.
​

2.) Use the % moisture to figure out how much water to add.

3.) For example, if your compost sample is 40% moisture, you will compensate by adding only 60% of the water you would need if the sample were air dried (0.60 x 5 ml = 3 ml water needed).

4.) Weigh or measure 5 g samples of compost into small containers.

5.) Add the calculated amount of distilled water to each sample.

6.) Mix thoroughly for 5 seconds.

7.) Let stand for 10 minutes.

8.) Read the pH with pH paper or a calibrated meter and record as compost pH in water, or pHw.

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mad librettist said:

sorry to butt in - secondtry or anyone, could you tell me how porosity, etc... change when media are fully colonized by roots like cannabis has? I know the medium itself doesn't change, but what if you take the whole system as an aggregate, roots and all? The values are different from empty media, no? Is the difference between the two always the same?

Click to expand...

Yea the media properties change, and roots actually penetrate into some OM like peat, APBF, etc. It's really hard to tell how it will change, but the link DC provided about finding porosity can be used (if one doesn't mind hindering the plant in the media). The problem is AFAIK it's hard to make a valid projection of what will happen, root morphology has much to do with level of nutrients in the media and moisture content. The benchmarks I provided (I assume) take into account the growing plant roots effects on media properties because those properties (of rootless media) are ideal for (most) crop and ornamental plants like cannabis.

HTH

So I can help myself if my medium is imperfect by always having roots?

Huh?

well it's off topic a bit, but I'm thinking what you can do if the medium is going to be less than ideal.

and I've been reading about using weeds to help crop plants along in crappy soil.

Hey,

If the media is going to be less than ideal why not make it ideal, or close to it before planting? LC mix, Pro-mix, SunShine mix, etc, grow cannabis well but they are not even near ideal, however, I wouldn't call them crappy. (unless I am confused about your suggestion)

All the best

Ah. I'm talking no-till and companion/successive planting. I remember reading maryjohn discussing it with Ganja Din (miss them dearly).

As you know I'm committed to a 14 gal tub of mineral soil as my next experiment. Since you've pointed out the flaws, I'm hoping to mitigate them. Without mixing.

Oh, OK, I see,

That is a different issue. The roots, bacterial bio-film, mycospheres (hyphae/mycelium/exudates/etc), etc., will help hold the particles in place, keeping the AP from dropping to far. That is why I like no-till, we rely upon the soil food web to hold aggregates and particles in place. I also add earthworms to my mix so they can continually add fresh EWC and help keep AP up in the media (food for the worms is the bounty of bacteria, etc, within the OM in the media).

Here is another edited excerpt from my paper where I compiled and compare the properties of 5 different soilless mix types:
(to all: this is info is copy-written by me, do not re-distribute this info in a non-free platform (e.g., a book, magazine, etc)


See my previous posts here too see what the abbreviations mean:
https://www.icmag.com/ic/showpost.php?p=3192959&postcount=33

Physical and chemical properties on five common soil-less mixes and bases:

(some references)

Fonteno, et al.

“Procedures for Determining Physical Properties of Horticultural Substrates Using the NCSU Porometer”​

Awang, et al.,

“Chemical and Physical Characteristics of Cocopeat-Based Media Mixtures and Their Effects on the Growth and Development of Celosia cristata”​

Robert R. Tripepi.

“What Is Your Substrate Trying to Tell You - Part V – Substrate Examples”​

Remember that these figures change with changing container height, and for greater healthy plant growth the AS should to be ≥ 15%, while for healthy aerobic soil food web the CC should be ≤ 65%.

APBF (particle size ≈ 2 to 3 mm):

TP = 75 – 80%
CC = 60%
AS = 19 – 24%
BD = 0.2 – 0.25 g/cm^3
MW = 1.5 g/g
CEC = ≈ 30 meq/100 g
pHw = ≈ 4.5 – 5
EC = ≈ 0.8
C:N = ≈ 100:1

Canadian Sphagnum peat:

TP = 89 – 94% (!)
CC = 75 – 82.5% (!)
AS = 12 – 20%
BD = 0.06 – 0.10 g/cm^3 (!)
MW = 3.0 – 5.0 g/g
CEC = ≈ 100 meq/100 g
pHw = ≈ 4
EC = ≈ 0.6
C:N = ≈ 50:1

Canadian Sphagnum peat-lite (e.g. Pro-Mix, LC-mix):

TP = 85 – 88%
CC = 70 – 75% (!)
AS = 9 – 10% (!)
BD = 0.10 – 0.14 g/cm^3 (!)
MW = 2.5 – 2.75 g/g

Coconut-coir (fiber):

TP = 92 – 95% (!)
CC = 80 – 85% (!)
AS = 11 – 14% (!)
BD = 0.07 – 0.08 g/cm^3 (!)
MW = 4.0 – 6.0 g/g
CEC = ≈ 60 meq/100 g
pHw = ≈ 5 – 6
EC = ≈ 0.8
C:N = ≈ 80:1

Coconut-coir mix:

TP = 82 – 85%
CC = 70 – 78% (!)
AS = 9 – 12% (!)
BD = 0.09 – 0.15 g/cm^3 (!)
MW = 2.5 – 3.5 g/g

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secondtry said:

Also, will you ask him to clear something up for me: Which method to find pH of media is ideal or most common:

1) The PourTru method tho find media pH (i.e., pH of media water = pHw):
http://www.ces.ncsu.edu/depts/hort/floriculture/crop/crop_PTS.htm


2) Or the methods suggested by Cornell U., to find pHw by drying media sample (option A below):
http://compost.css.cornell.edu/monitor/monitorph.html

Click to expand...

Great question. If Dave Coulier won't or can't e-mail the author and ask, I certainly will.

I recently found this reference, but it's not exactly from a credible source. I'm curious what recently published contrary viewpoint they are referring to though:

A pH measured in the supernatant liquid may be considerably different than the reading obtained by placing electrode in the slurry at the bottom. For a long time it was believed that this "supension effect" is created by the large junction potential caused by the presence of charges on the soil particles. A contrary view was published more recently which argued that the charges on the soil particles either held or repelled hydrogen ions, and that the difference in readings was a true estimate of real differences in pH which existed between the suspension region and the supernatant liquid.

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Hey all,

I have gotten a few PMs asking for all of my in-progess soilless mix so I thought I would post it here. I also updated the thread starting post.

Here is an edited excerpt from a (working) paper I have been writing for some time:
(to all: this is info is copy-written by me, do not re-distribute this info in a non-free platform (e.g., a book, magazine, etc))

I also supply fertilizer when drench watering with hydrolyzed fish, kelp extract, guano, etc. This media is not supposed to supply all the fertilizers for plant growth, but to provide a base of food for plants and microbes (e.g., to jump-start the N-cycle from guano). To supply extra Ca I foliar spay NOA/OMRI certificated Ca as amino acid chelate.

My current (untested) soil-less mix:

In containers at least 12 inches tall, and no "drainage layer", the following soil-less mix should provide ideal properties to plants and microbes.

(vol/vol)

• 7 parts APBF; screen from 4 mm to 2 mm; pre-moisten with hydrolyzed fish/H2o/yucca surfactant

• 1.5 part peat; screen from over 2 mm

• 0.5 part high quality compost; screen under 4 mm; humus rich and mature with mean levels of SFW organisms and should be fresh with MC ≥ 45%

• 0.5 part high quality vermicast (aka vermicompost and EWC); screen under 4 mm; should be fresh with MC ≥ 45%

• 0.5 part biochar (pyrolyzed) rice hulls; screen from 4 mm to 2 mm; pre-moisten with hydrolyzed fish/humic acid/yucca/H20

• 3 – 10 lb of powdered lime (50/50 mix of calcidic/dolomitic) per yd3 of media; ideal pHw is 5.5 to 6.5 (too much Mg can make media crusty)

(by dry weight of media)

• 4 – 6% azomite powder

• 4 – 6% zeolite powder

• 1% high N bat or seabird guano or preferably add high quality hydrolyzed fish to drench H2o

• 1 – 2% kelp extract powder or preferably add high quality kelp extract

• 1 – 2% un-refined dark molasses crystals or preferably add unsulfured black strap molasses (ideally ≥ 80 brix) to drench H2o

• 1 – 2% humic acid powder or add humic acid liquid extract to drench H2o

• 1 – 2% colloidal phosphate powder or soft-rock phosphate, etc

• Yucca powder (as surfactant mix only with peat, APBF and rice hulls)

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