Fertilizer?

[Ray]

Phred - My gut feel is that fertilizer choice might help, but won't cure your issues with the water supply you're using. It's that high alkalinity and sodium levels that would be my focus. Have you considered RO?

 

[myxodex]

Phred, I agree with Ray about your water. Na is way too high. I think K-Lite would be the worst choice with your water as K and Na are competitors for uptake. If you have enough rain and can collect rain water do so, ... and invest in a water butt. Alternatively, you could go down the RO (reverse osmosis route) or use a rechargeable ion exchange resin as used by aquarists.

 

[myxodex]

Time and time again, the best paphs I see here from various good growers are invariably fed with urea..(nitrate and ammonium is very low) Usually cheap house plant fertilizers. They have big deep green leaves with more offshoots and fantastic vigour, flower every year, and grow fast enough to require dividing regularly.
In these fertilizers which are usually around 20-3-10 (aprox), the magnesium is often low. (it is assumed that there is enough in the water already) Most growers use magnesium sulphate a couple of times a year as a boost and they add dolomite on the p/mix surface from time to time. It's the direction I am going with fertilizing but I still like to use an organic fraction and I add nickel to the trace element mix because it is needed for the urea processing and the fertilizer people still have not realized this..

I also add nickel although it probably isn't necessary. Nickel is required at such low levels and given that Fe, Mn and Zn preparations often have Ni as a contaminant (it is unlikely that any of the plant food manufacturers use analytical grade materials due to the high cost). However there is a situation where adding Ni is a relevant precaution, i.e. with fertilisers that contain cobalt. Excess cobalt can interfere with Ni utilisation by the plant and so mimic a Ni deficiency. Cobalt is not yet proven to be a plant micronutrient but is nonetheless incorporated into many commercial fertilisers as a micronutrient. Interestingly, Co is needed by quite a few plant growth promoting bacteria and I wonder if it's this indirect effect that lead researchers to suspect that it was a plant micronutrient.

I've said this before, but it's worth repeating. The link between N and S is routinely forgotten when labelling a fert with the NPK. Plants just cannot use N if there isn't enough S and most single preparation fertilisers do not contain enough S to use all the N provided. This may be OK with garden fertilisers where ground water is used (it usually has enough S), but with fertilisers that are aimed at RO water use this is crazy ... because the plants simply cannot use a good fraction of the N supplied. I know of only one fertiliser in the EU that is designed for RO or rain water : Akerne's rain mix it has N, 11.8 : P, 2.7 : K, 13.7 : S, 4.8 , which is more than enough S for the plants to assimilate all the N.

 

[Stone]

I also add nickel although it probably isn't necessary. Nickel is required at such low levels and given that Fe, Mn and Zn preparations often have Ni as a contaminant (it is unlikely that any of the plant food manufacturers use analytical grade materials due to the high cost). However there is a situation where adding Ni is a relevant precaution, i.e. with fertilisers that contain cobalt. Excess cobalt can interfere with Ni utilisation by the plant and so mimic a Ni deficiency. Cobalt is not yet proven to be a plant micronutrient but is nonetheless incorporated into many commercial fertilisers as a micronutrient. Interestingly, Co is needed by quite a few plant growth promoting bacteria and I wonder if it's this indirect effect that lead researchers to suspect that it was a plant micronutrient.

I've said this before, but it's worth repeating. The link between N and S is routinely forgotten when labelling a fert with the NPK. Plants just cannot use N if there isn't enough S and most single preparation fertilisers do not contain enough S to use all the N provided. This may be OK with garden fertilisers where ground water is used (it usually has enough S), but with fertilisers that are aimed at RO water use this is crazy ... because the plants simply cannot use a good fraction of the N supplied. I know of only one fertiliser in the EU that is designed for RO or rain water : Akerne's rain mix it has N, 11.8 : P, 2.7 : K, 13.7 : S, 4.8 , which is more than enough S for the plants to assimilate all the N.

I have been looking for cobalt lately to include it but have not found a source as yet. Important for legumes apparently but I would like to include it for the micro organisms in the medium for the reasons you mentioned. I only have one fert with cobalt but it has too much P so I need to find some CoSO4. Most of those ''cheap'' fertilizers I mentioned use potassium sulphate as the K so no issue with S in those. In the big cities there is possibly also enough S in the air and water too but not where I am. Have you seen the nickel/urease connection? https://www.sciencedirect.com/science/article/pii/S016894521200221X
Of course you don't need to worry about any of these things if you use organics. In the ''old days'' when they used fern fibre, moss, forest mulch, soil, manure, compost, humus, leaf mold etc, they used no fertilizer at all for one or two years with no growth problems. We only really need it for the sterile mixes we use today.

 

[Phred]

Phred - My gut feel is that fertilizer choice might help, but won't cure your issues with the water supply you're using. It's that high alkalinity and sodium levels that would be my focus. Have you considered RO?

Hi Ray
Yes I have considered RO but am having trouble finding a place to locate the collected water. I use between 5 and 25 gallons a day watering.

 

[Phred]

At the moment in 5 gallons of my tape water I add 1/2 tsp Calcium Nitrate, 1/4 tsp gypsum (Calcium Sulfate), 1 tsp Epsom salt (Magnesium Sulfate), and a mineral mix. I lower the pH to about 5.7-6.0 with a 10 part citric acid to 1 part malic acid solution I make.

 

[Ray]

Hi Ray
Yes I have considered RO but am having trouble finding a place to locate the collected water. I use between 5 and 25 gallons a day watering.

Fred, there are a lot of tank options.

When I first started, I got two, 55-gallon drums for free from a local car wash and built a 4x4 stand so one could be above the other, so the whole thing only occupied a of about 2'-6" square. The RO system fed the upper one through a float valve, so it would automatically stop, and I refilled the bottom one (where I added fertilizer and additives) by opening a spigot I had installed in the sidewall near the bottom.

There are rectangular polyethylene tanks available as well, and if stood on an end, take up very little floor space. For example, plastic-mart.com has a 50 gallon tank that when stood on end, only occupies about 22" x 9".

 

[myxodex]

I have been looking for cobalt lately to include it but have not found a source as yet. Important for legumes apparently but I would like to include it for the micro organisms in the medium for the reasons you mentioned. I only have one fert with cobalt but it has too much P so I need to find some CoSO4. Most of those ''cheap'' fertilizers I mentioned use potassium sulphate as the K so no issue with S in those. In the big cities there is possibly also enough S in the air and water too but not where I am. Have you seen the nickel/urease connection? https://www.sciencedirect.com/science/article/pii/S016894521200221X
Of course you don't need to worry about any of these things if you use organics. In the ''old days'' when they used fern fibre, moss, forest mulch, soil, manure, compost, humus, leaf mold etc, they used no fertilizer at all for one or two years with no growth problems. We only really need it for the sterile mixes we use today.

Cobalt is used in glazes by potters. It's quite expensive; comes as either the oxide or carbonate, see pottery supply vendors. The carbonate is easy to dissolve in sulphuric acid, but you would need filter paper/coffee filter to get rid of the residue. This stuff is very impure and has who knows what as contaminants, but given the amount you need is so small the contaminants probably don't matter. Personally, I wouldn't bother as it's probably there in sufficient quantities as a contaminant anyway.

 

[myxodex]

At the moment in 5 gallons of my tape water I add 1/2 tsp Calcium Nitrate, 1/4 tsp gypsum (Calcium Sulfate), 1 tsp Epsom salt (Magnesium Sulfate), and a mineral mix. I lower the pH to about 5.7-6.0 with a 10 part citric acid to 1 part malic acid solution I make.

Phred, another idea you could try is zeolite filtration. You are adding citric acid to neutralise some of the alkalinity in your water. Adding the acid isn't going to remove the Na, but with zeolites you can add the acidity AND remove the sodium. This is especially useful for alkali metal ions like potassium and sodium which have a good affinity for zeolites.

You would need to find a source of a natural zeolite like clinoptilolite in a granular or sand like form.
It would need to be from a reliable source that gives the CEC (cation exchange capacity).
This is usually given as cmol/Kg or meq/g.

Clinoptilolite is one of the common natural zeolites and can have CEC's of about 1.8 - 2.2 meq/g.

Your water has ~ 58 mg/l of Na, this is equal to about 2.5 meq/l . This is calculated by dividing the mg/l by the molecular weight of Na so 58/23 = 2.5 meq. So you would need 1.25g to treat 1 litre (if the CEC is 2 meq/g), ... the trick is that you can reuse the zeolite.

Natural zeolites like clinoptilolite have an acidic threshold below which they start binding H+ and releasing metal ions, so when H+ is high the Na+ will be released and H+ will bind. Treating the zeolite with an acid will increase the CEC several fold because the natural zeolite comes with cations bound, so it would be a good idea to activate the zeolite to begin with because you would be stripping out any bound metal ions or ammonium ions. The ideal acid if you can get it would be nitric acid, but citric would work, you just need to reduce the pH to about 3.0 to reactivate the zeolite. Obviously hydrochloric acid would be a bad choice, because which ever acid you use some of it will end up in your treated water.

When you treat with acid the pH will resist dropping a bit at first because the zeolite is absorbing the H+ so you need to add enough acid to get the pH down to about pH 3.0. Don't overdo this as very low pH can destabilise some zeolites. Then you give one more acid rinse to get rid of the metal ions in solution, then drain the solution and you are ready to go. This method works better if your water has moderate alkalinity as yours does. The reason is that when you treat your water, the zeolite will bind Na+ and release H+, so without the alkalinity it will lower the pH of your water too quickly and the reaction will become less efficient. Remember the zeolite will lose it's binding capacity for metal ions below pH 4.0 - 5.0 depending on the particular zeolite.

For 50 gallons you would need 238 g of zeolite (I would use a bit more say 250g).
The calculation goes as follows:

50 gallons is about 190 l, so about 475 meq of Na, so total meq / CEC in meq per g = 475/2 = 237.5 g
Note the zeolite will remove the K as well so a bit more will be needed.

Exactly how you set this up will be down to your ingenuity, but an up-turned water bottle with the base cut off and the neck stuffed with plastic (polyallomer) wool could work as a filter. The more zeolite you use the faster the flow rate you can get away with, because although the binding is fast, all the water has to contact the zeolite in passing through.

 

[Heather]

Wow. You guys are amazing. So I think that’s a no, to my simple question. Think I’ll order some MSU again or k-lite. Thanks all!

 

[Ozpaph]

chemistry PhD???