Komplex or free ions????

[Rick]

Are you going to use some mix of calcium and magnesium sulfate to pick up the S?

Is this a hydroponic tank mix, or do you apply intermittently?

 

[DavidCampen]

This is what I use every time I water. I do not grow hydroponically. I grow in fir bark, spaghnum or some mixture thereof depending on the plant. For plants that call for bark then for pots over 4" diameter, for improved drainage, the bottom of the pot will have a small inverted plastic mesh pot with hydroton (now hydrocorn) around the periphery. My watering wand was taken from a pesticide sprayer, the water comes from my pressurized RO tank and goes through a chemical injection pump (Dosmatic brand) where the nutrient concentrate is added.

I would probably use ammonium sulfate to increase the sulfur, in part because I already have a stock solution of this. When I prepare a batch of nutrient concentrate I don't work with dry materials but use stock solutions. Calcium ammonium nitrate and magnesium nitrate stock solutions contain 400 grams/liter, potassium dihydrogen phosphate solution is 100 g/liter, all the others are somewhere in between except for the minor elements which are much more dilute.

 

[myxodex]

Very interesting thread. I really like the idea behind this approach; better uptake = lower nutrient concentrations needed, which chimes with what I'm getting from all the fert threads here. I do have a little concern about aa's causing excess bacterial growth. I came across this US patent that some of you might find interesting that fits nicely with David's use of both aspartate and citric acid http://www.google.com/patents?id=wysgAAAAEBAJ&printsec=abstract&zoom=4#v=onepage&q&f=false
Unfortunately it's annoying full of legalese and the experiments don't answer questions I have (e.g. no comparison with EDTA or EDDTA).
Anyhow thanks for posting.

 

[DavidCampen]

Interesting. There is no bicarbonate in this system at all (unless you have pot supplements). So why the high percent of ammonia?

Less than 20% of the nitrogen as ammonium doesn't seem high to me.

By bicarbonate I guess that you mean buffer capacity. You don't particularly need buffer capacity; to take up a cation the plant releases H+ and to take up an anion the plants releases OH- (in the form of bicarbonate). The H+ from the uptake of cations and the OH- from the uptake of anions neutralize each other producing water. But that said; the ammonium, aspartate, citrate and phosphate provide buffer capacity.

 

[Rick]

You don't particularly need buffer capacity; But that said; the ammonium, aspartate, citrate and phosphate provide buffer capacity.

http://www.firstrays.com/PDF/Part 3 - Fertilizers.pdf

Check this out. Bill Argo is pretty much the one who came up with MSU ferts (high and low alkalinity use versions).

I'll dig up the link showing uptake models in plants that show the use of bicarbonate ion to move other ions in and out of plants.

OH (rather than bicarbonate ion) measure is really a poor surrogate for understanding buffering capacity in plans and soil systems.

 

[Rick]

http://www.verdegaalbrothers.com/ph_meters/Uses_of_sulfuric_acid_as_water_admendment.pdf

Here's another fun play paper.

 

[DavidCampen]

http://www.firstrays.com/PDF/Part 3 - Fertilizers.pdf

Check this out. Bill Argo is pretty much the one who came up with MSU ferts (high and low alkalinity use versions).

I'll dig up the link showing uptake models in plants that show the use of bicarbonate ion to move other ions in and out of plants.

OH (rather than bicarbonate ion) measure is really a poor surrogate for understanding buffering capacity in plans and soil systems.

Yes, the _plant_ produces bicarbonate (HCO3-) from OH- and CO2. You don't need bicarbonate in your nutrient solution. Yes, OH- is not a buffer.

In fact, Bill Argo states on the 1st page of the link you gave:
" ... uptake of nitrate nitrogen increases substrate-pH because OH- or HCO3- (bases) are secreted by plant roots in order to balance nitrate uptake."

That would be a good paper to study.

 

[DavidCampen]

http://www.verdegaalbrothers.com/ph_meters/Uses_of_sulfuric_acid_as_water_admendment.pdf

Here's another fun play paper.

That paper talks about how to get _rid_ of carbonates from irrigation water using strong acids. I don't use water from an irrigation ditch for my orchids. I use RO water.

 

[Rick]

That would be a good paper to study.

Yes, read on. There is a section in there about alkalinity of feed water. There is also a good table in there that shows fert selection (and %N from ammonia vs nitrate) based on alkalinity in the system.

 

[DavidCampen]

Yes, read on. There is a section in there about alkalinity of feed water. There is also a good table in there that shows fert selection (and %N from ammonia vs nitrate) based on alkalinity in the system.

Um, actually, I was suggesting that other people should study the paper. I already know everything that is there.