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Found some interesting recipes and/or info on the various N-P-K values of some common organic compounds. What do you use for inputs for your fish-less systems?

"Instructions for Preparing Organic Fertilizers
Organic fertilizers need not be expensive and can be made on your own. This recipe,
to the best of my knowledge, was created by Steve Solomon, founder of Territorial
Seed Company. All measurements are shown in terms of volume, not weight.
4 parts seed meal
1 part dolomite lime
1/2 part bone meal or 1 part soft rock phosphate
1/2 part kelp meal
1. Seed meal provides N and smaller amounts of P and K. Some states prohibit its use
in certified organic operations (not something a home grower needs to be
concerned about). Other options are afalfa meal, or rape/canola meal. The NPK
value of cottonseed meal is about 6-2-1. Bloodmeal can be substituted in place of
some seed meal, since it acts more quickly. Use three parts seed meal and one part
bloodmeal. Seed meals tend to be acidic, so lime is included to balance that.
Dolomite limestone is roughly half magnesium carbonate (MgCO3) and half calcium
carbonate (CaCO3). Calcitic limestone is pure calcium carbonate. Plants usually
need more Ca than Mg, therefore a mix of 2/3 dolomite lime and 1/3 calcitic lime
is recommended.
2. Bone meal and rock phosphate provide the bulk of the P component. Less bone
meal (NPK 0-10-0) is required since it releases its P more readily. The advantage of
using rock phosphate (NPK 0-3-0) is that it continues to contribute P to the soil over
many years. Bone meal is produced as a byproduct of the beef industry while rock
phosphate is mined.
3. Kelp meal (NPK 0-0-10) contributes K and micronutrients. It tends to be more
expensive than the other components. Another possible K source is Jersey
greensand. It has the same advantages and liabilities as rock phosphate (very slow
release) but does not supply micronutrients. Wood Ash is also a plentiful, viable source of K.
Formulas for Balanced, All-Purpose Organic Fertilizer, Fertilizer Ratio
Fertilizer Ratio (N-P2O5-K2O) Ingredients:

2-3.5-2.5  -1 part bone meal
3 parts alfalfa hay
2 parts greensand

2.5-2.5-4 - 3 parts granite dust
1 part dried blood
1 part bone meal
5 parts seaweed

4-5-4 - 2 parts dried blood
l part phosphate rock
4 parts wood ashes

3.5-5.5-3.5 - 2 parts cotton seed meal
1 part colloidal phosphate
2 parts granite dust

0-5-4 - 1 part phosphate rock
3 parts greensand
2 parts wood ashes

2-8-3 -  3 parts greensand
2 parts seaweed
1 part dried blood
2 parts phosphate rock

Substance Nutrient:       Elements Supplied:

Blood meal                   15% N, l.3% P, 0.7% K
Dried blood                   12% N, 3.0% P, 0% K
Bone meal                    3.0% N, 20.0% P, 0% K, 24 to 30% Ca
Cottonseed meal           6% N, 2 to 30% P, 2% K
Fish emulsion, fish meal 10% N, 4 to 6% P, 1% K
Hoof and horn meal        14% N, 2% P, 0% K
Leatherdust, leather meal 5.5 to 22% N, 0% P, 0% K
Kelp meal, liquid seaweed 1% N, 0% P, 12% K

Calcite, calcitic limestone 95 to 100% calcium carbonate
Colloidal phosphate or soft
omission                             0% N, 18 to 20% P, 27% Ca, 1.7% iron phosphate, silicas, 14 other trace elements
Dolomite, dolomitic
51% calcium carbonate, 40% magnesium carbonate
Granite dust, granite meal,
crushed granite minerals      0% N, 0% P, 3 to 5% K, 67% silica, 19 trace

Greensand, glauconite          0% N, 10% P, 5 to 7% K, 50% silica, 18 to 20% iron
oxide, 22 trace minerals
Gypsum (calcium sulfate)      23 to 57% C, 17.7% S
Langbeinite                           0% N, 0% P, 22% K, 22% S, 11% Mg
Rock phosphate                    0% N, 22% P, 0% K, 30% Ca, 2.8% Fe, 10% silica, 10
other trace minerals
Sulfur                                    100% S

Composted cow manure          2% N, 1% P, 1% K
Guano (bat)                            8% N, 40% P, 29% K average, but varies widely, 24 trace
Guano (bird)                           13% N, 8% P, 20% K, 11 trace minerals

Rabbit                                    2.4%N, 1.4%P, 0.6%K

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Replies to This Discussion

Well egg shells will buffer pH up the way all other calcium  carbonate does and the ashes will also have the effect of raising pH.  The hummonia will start off with a high pH if it's been aged but the nitrification process bringing the pH down can definitely help things.  Some hydroponic nutrients add ammonia to do just this, keep the pH down and combat hard water with the nitrogen cycle though that is tricky if the hydroponics systems they are used in are well sterilized it could take most of the growing cycle to really take effect.  I've also see hydroponic pH down that had ammonia in it so now I'm careful to caution people to read the labels before assuming hydroponic pH down would be safe to use in a system with fish.

Tell me more about rusty nails, Vlad. When I first got into Aquaponics, I read a few accounts of rusty nails in the GB supplying iron. Later, I read that rust and/or nails will never morph into a plant usable form of iron. How is it done in nature, and why is iron def so rare in dirt farming?

I've read that molasses might be a used to chelate, but an article by "farmer brown's aquaponcs" stated that plants did not respond to a foliar spray or root soak of iron soaked in molasses. The rust did disappear into the molasses solution, though, just didn't help the plants.

Found a comment by Rupe in BYAP I think;
"Mineral supplementation in cases of high pH can be done with "chelated" minerals.... which can be taken up regardless of pH in chelated form..

Chelated iron is the perfect example... and the most common ph related deficiency...

And is an example that Dave alluded to.... in that "rusty nails" wont provide iron in a form that can be taken up... resulting (from memory) in non-soluble "ferrous" ions... rather than the soluble "ferric" ion.... which is essentially what the chelation process results in...."

Also, I do live by the sea, and have often wondered about using seawater. I raise tilapia, so no prob there. But at what dose would I add seawater and be safe for sodium toxicity?

Over on another forum years ago there was a discussion that talked about how it might be possible to chelate Iron naturally in an anoxic environement with some sugar.  So a low oxygen environment with some molasses and iron and perhaps some would be converted into plant usable form.  Of course such a filter would also likely convert nitrate back to nitrite so one must be careful.

Lets see, Here is a link to that old discussion

Conversations with a Really Smart Guy (RSG)

So if you ever see me call something an RSG filter, this is where it comes from.

Sorry Vlad, but I too wonder about your theories about rusty nails and sea water. I certainly don't think it would hurt to put some old nails in say the grow beds of a flood and drain system. I too put iron in my operation but I put it in my compost where I think is more microbial activity to chelate raw iron/ iron oxide.

As for sea water, I don't think the sodium salt vs micro element ratio is conductive in the long run due to salt buildup over time. On the other hand, I think occasional doses would be very beneficial.

While reading in the forums from 'down under'....I saw several of them add salt on a regular and 'on going' basis. They use  refractometers to check the salt level and they say after a period of time, they need to add more. Most maintain 1 -2 ppt.

 It turns out, plants actually make good use of the sodium.

This is from 'Plant Physioligy'.....

Potassium deficiency can be greatly alleviated in the presence of sodium but the resulting sodium-rich plants are much more succulent than a high potassium plant. In some plants over 90% of the required potassium can be replaced with sodium without any reduction in growth.


Jon, I use sea salt,  at the rate of .5 ptt.  Sea water, I believe is like 32 ppt.

David, thanks for that. I'll add some seawater to my system. Easy enough to figure how much to initially add at 32 ppt, but how do you measure ppt for topping up?

TC, great link. I just read it start to finish. Pretty heavy in the beginning. Do you use your RSG filter for reducing nitrate, or chelating iron? Haw exactly did you configure it? I like the flow thru pipe design.

For those of you that didn't read, or didn't finish, TC's link to the BYAP thread, the gist is: iron can be biologically chelated by anaerobic bacteria in the presence of carbon, like sugars, molasses, or carbon media. There was also mention of requiring acetates and lactates, and hi pH. There was a lot of info from different sources, so it's a bit muddy in my mind still. Much of the discussion was oriented towards removing nitrates. Personally, I have room and resources to add more growbeds, and don't have any desire to off-gas my nitrates as atmospheric nitrogen. But I do have interest in supplying iron without buying it at the nursery. I would feel better about a complete AP system with nothing added that did not originate from household resources. Everyone has enough rusted metal on hand, or dumped in the trash, to consider iron a household resource.

I have been looking for the natural system that makes iron deficiency uncommon is nature, yet so very common in AP. I think anaerobic bacteria makes a lot of sense. We go over the top to eliminate stagnant spots, and dose with chelated iron as if that's the "right" way to do it. Every body of water I have been to has a an anaerobic floor of stinky, black muck that smells like sewer, especially if it is rich in organics. At the beach here in Cali, if you dig in the sand at low tide, this black stinky sewer sand is only about 6-12" down, and stretches under evey foot of ocean. The surf pounds the shoreline with oxygen, making probably the most intense zones of aerobic bacterial life on the planet, yet 6" down under the sand it's anaerobic and stinky.

So, I'm envisioning a sump tank with a few inches of iron and lake muck, maybe some milk (for lactates) and molasses and activated carbon (for sugar and carbon source), some ashes (for minerals and hi pH), covered by a few inches of sand with clams or muscles, covered by a few inches of running water that never gets pumped dry from the sump pump. Should be an iron producing battery! Maybe some unknown benefits as well. The clams are already suited to that environment, and their movement will help stir the zone between bacteria and help move along the nutrients.

Smart or silly?

@Jon & @Carey, Now I definitely understand Carey's (and my own) apprehension on whether rusty iron would do a damn thing to help plants. I'm sure you noticed that my statement was "A couple grams of rusty nails helped too, i think".

Now, although I can fully explain why it is that I think that, I am  still aware that just because I do think it, that doesn't necessarily make it true. I don't want to give people the wrong idea (especially anyone new) that just tossing a few rusty nails into a grow bed or DWC trough will take care of any iron deficiencies that may crop up (though I doubt that it could hurt anything). It is a long and well established FACT that ferric iron (Fe3+; the domain of rusty nails) is pretty useless and cannot be absorbed by plants. Unlike ferrous iron (Fe2+) which is plant available, and I am in no way saying otherwise. That being said though...

The first time I ever did this was in a little 'test' system with pH in the upper 7's to mid (upper even at times) 8's. I was full on expecting to see all sorts of (esp. iron) deficiencies, and half wondered if anything would even grow at all at that pH. I've always kept my hydro systems at pH5.8 - 6.3. This pH was to me, ridiculously high. This was a "worm-tea hydro" set-up to, in my own half-assed way, see what kind of growth I could expect in a newly cycled AP system. i.e hard water, high pH, with mostly just nitrates. Various plants (leafy greens salads, and lowish-nute needing peppers were put into the system These plants were all in different rooting mediums, or combinations thereof (all standard fare though... coir, vermiculite, hydroton large, hydroton, small, sand, worm castings, different combinations, or even by themselves in some cases)...There were only two (to my surprised delight) plants that showed Fe deficiencies. One with horribly dreadful inter-veinal chlorosis just about everywhere, the other much less so. All other plants were more or less alright. Both plants were COS lettuce type, and both were in net pots with only hydroton as the media...

We can all agree that there is much more going on in an average AP system than N.somona and N.bacter, right? Even the conventional wisdom/available studies, says that those bacteria 'like a pH of 8.5 and wont function at a pH around 6'. But, many well seasoned and respected aquapons run their systems at pH values between the upper 5's to lower-mid 6's, and appear to do so with no ill effects to their bio-filter? (Theories abound as to why this is, but the fact remains that we just don't know for sure)...So I put the shavings in there on the totally off chance that something somehow biologically speaking, might reduce even the tiniest amount of ferric iron to ferrous iron (bacteria, the plant roots themselves...whatever). I mean plants (generally speaking) really only need a minute amount of iron to stave off deficiency, like 2-3ppm (or mg/l) at the right pH of course. And even that may (or may not be, IDK) a high figure.

It seems like most all nutrient formulas (manufacturers as well as formulas given for reagent mixing, are based largely in some way or another on two formulas that appeared in the 1950 California Agricultural Experiment Station Circular 347, authored by a Dr.'s Hoagland and Arnon. We are now finding that the distinguished gentlemen were 'over doing it a bit' with the nutes. Not detrimental to plants, but certainly not efficient use of reagents either...And (even though subsequent research says that the 2-3ppm is iron ispretty solid) that got me thinking...What all did people use for iron in hydro formulations BEFORE chelates existed? Turns out, all sorts of stuff...and some of it was ferric? Iron sulfate (ferrous) FeSO4-7H2O, iron sulfate (ferric) Fe2(SO4)3, iron (ferric) chloride, FeCl3•6H2O, iron ammonium sulfate, FeSO4(NH4)2SO4•6H2O and two organic iron compounds that I've come across, iron citrate and iron tartrate...I have no idea how exactly in a sterile hydro environment any of those ferric compounds are reduced to ferrous ones? But, as a general rule it seems (at least it is written) to take twice as much of the above mentioned compounds than the already chelated forms of iron. It seems that the chemistry of iron in a nutrient solution and its uptake by plants is really quite complex (even for 'the experts' and especially for someone like me).  Again, the filings were (and now, are) being added in the off chance that even the tiniest bit of it is being reduced to a ferrous, plant available form.

My vote would be for Carey's compost pile (esp. his anearobic digester to do the job of reducing ferric to ferrous iron somewhat more properly), and I have no way of even knowing if the nails were responsible for anything (again it is my thinking that they were, at least a bit). It might have been pure coincidence, might be my water, might be the worms, might be a hundred different things in combination with one another...I have no way to really know... But I might not have given the matter another thought had the two plants showing Fe deficiencies not been both, the only two in hydroton only net pots...(probably is just coincidence, but it got me thinking about how iron reduction might take place? About different compacted media i.e coir, vermiculate, sand mixes...and it at least seems possible to me). Would I base a commercial operation on this "thinking"? Hell no, I went out and got me a box of Fe- EDDHAF chelate :) But I'm sure it doesn't hurt any either. And I'm also sure that there is much going on in our systems that we don't know or don't ever hear about. That's part of the reason I'm excited about an AP Association and the research such an organisation might eventually spur. (Once an actual AP "industry", in whatever form that may take, exists to finance such various research, of course).

Sorry I couldn't tell you anything more concrete Jon. (Btw...I'm not nit picking, just giving you a heads terms of plant availability I think you, or what you read perhaps, have the ferric and ferrous backwards...All elemental ions taken up by plants seem to be more easily absorbed in a mono-valent, as opposed to a di-valent form. So I'm gussing that a trivalent form (like ferric iron) is even more difficult, if not impossible for them to uptake...

As far as sea water...what David says..., and many people are already salting their systems to 1ppt. I wasn't suggesting using ALL seawater of anything (that'd be like having a 1000 litre system and using a 1000 litres of Max-Crop :)

Trace elements are only needed in traces, and I can think of no better (natural and free) substance than seawater for those trace elements. IMO, I don't believe their would be a problem receiving the benefits and avoiding the potential problems at or below 1ppt (though it seems like you often hear about strawberries not really liking the salt).

"Dammit Jim, I'm not a Doctor..." Hell I'm not even a scientist, so take all these thoughts as just that...thoughts. Constructive criticism (and/or encouragement/info when warranted) from you guys really helps me to stay on track. 

Thanks for the info and the link David.

Thanks Vlad. I saw the mix up between ferrous and feric in Rupert's quote, too, but not until after I read TC's link and became more iron educated. Sorry Rupe for quoting the mix-up, but the point I pulled from the comment was that chelated iron is usable regardless of pH. Hope that is still sound advice.

Vlad, the research TC linked may very well give basis to the idea that rusty nails do eventually yield some ferrous ions. One of the forum posters had a ton of rusty iron in his system and never had an iron deficiency. Another who used nails had to add chelated iron when his system was new, but at some point quit adding and never again had a deficiency. Your test among medias lends support to the same idea, as hydroton was most likely to remain aerated, and thus least likely for anaerobic pockets to do their iron work. Anaerobic pockets in the fish tank are bad news, because when stirred up they pollute with ammonia and sulfur (right?), but the floor of a grow bed should be able to go anaerobic without worry, and iron or rust anywhere in the system will settle to this zone, possibly converting to ferrous ions.

I'm not stating any of this as fact, just throwing it out there for you RSG's to agree or disagree, bounce some ideas.

Carey, could you post a link to your anaerobic digester. Sounds interesting.
RSG means "really smart girl" too, TC :|

Wow, thanks for that link TC...I'm still reading it, had to take a break, quite a bit of links in the link :) though some of them appear to be 'broken' (404- not found), while others you have to pay to read in their entirety :(

Jon, I'm not done reading the thread, but so far I'm pretty much getting what you've described 3 posts ago. Not really interested in removing any nitrates either, since I'll be hunting for the lowest possible stocking density for my big-ish 'hybrid' (seems that what DWC raft, filtered by media bed systems are being called) system. But, would be more than thrilled (I'm all tingly already) at the possibility of an RSG filter (super cool name hehe) doing the iron reduction bit. I have more shavings and filings than I could use in 3 lifetimes.

Speaking of shavings, I have bag-fulls of long thin curly PVC shaving (off the lathe). I saved them after having to modify everyone of my bulkheads, PVC adapters, fittings etc... (don't ask) to get them to fit, and was hoping to put them in some netting (bag) in a sump for a bit of extra biological surface area. Does anyone know of why this might be a bad idea?

It was an old Thread Vlad and not even mine. 

I've never personally set up a RSG filter myself (though I expect the very bottoms of most older media beds are probably containing some small pockets of anoxic conditions that could act that way.)

I too have noticed that certain media conditions seem to yield plants staving off the effects of deficiencies better than some other conditions, especially under less than favorable pH and nutrient balance conditions.  My "Big" AP system that has started out with about 40% of its gravel beds being filled with shells, well I've grown plenty of plants in the media beds and with regular doses of iron and seaweed extract they survived and some even thrived.  Now I also ran an NFT pipe as well as some raft bed during this time and I note the plants in raft and NFT did not fair as well against the deficiencies as the ones in media beds with all the gunk and worms associated.  So the media (and everything living in it) does affect the well being of the plants and that is even more apparent as conditions become less favorable for plant growth.  At least that is my observation in in central FL, the land of the limestone aquifer (my well water is hard so even without the shells, the pH tends to say high when I don't get enough rain.)

Ok guys (esp Jon), So lets re-cap. Supposing we all agree on the conditions necessary to redox Fe3+ to plant usable Fe2+.

Meaning: Anoxic conditions, a Carbon source, organic polymers the merrier (humic acids etc...) and time...

As I've said (asked) in a couple of different threads already..."how useful is this considering that once your redoxed Fe2+ hits oxygenated water it will oxidize back to Fe3+ ? ...

How quickly and under what conditions does this oxidation (to useless Fe3+) take place? Seconds? Hours? Days?

"The Net" seems to be lacking in such specific answers, so I've employed the help of a band mate who happens to be a chemist. After the initial responce of ...

"Dude, I'm a chemist at a pharmaceutical company, I have a girlfriend (which takes up most of my free time) and I play in your stupid band, which takes up the rest of my free time...How the Hell am I supposed to know something like that"?...  

I decided to continue to pick his brain further during all the remaining beer drinking free time that was  available...Between my understandings of the various studies/science and these Lager whetted conversations, this is what I've come up with...

As we already know...with every chemical reaction that takes place in nature, pH as well as temperature will play a critical role in how fast (or even IF) a given reaction will take place...

1). In the case of Fe2+ reverting back to useless Fe3+, there will probably exist a certain DO threshold at which oxidation will take place. This threshold (originally determined ) to be "Beats me"? ....has now been upgraded to 2 to 3 mg/L (ppm). ...Well below most of our system parameters, and what even talapia or common carp will bear. So, not good so far...

2). At a pH of much higher than neutral (8-9) oxidation of Fe2+ to Fe3+ will take only seconds. This is good since most AP system pH parameters will be well below that level because of the plants.

3) At a neutral pH the colder your water temps the longer your usable Iron will last...At say 20C degrees you may only have an hour or so...Again NOT good for talapia (Jon), ok for common carp (me). BUT...the good news is...

4). At lower pH...say 6 you should have a good 3 or 4 days worth of of hard earned usable Iron (Fe2+) floating through your system before it reverts to Fe3+  even near talapia temps (20C degrees)

Now, many seasoned aquapons (and Jon, I count you among them) keep there systems hovering just above or below a pH of 6...So all would seem well for 'ol double barrel RSG 2.0...

If anyone can add to, confirm or deny any of the above (you know who you are, and you know that your thoughts, ideas and advice are vastly appreciated and valued ) it would be a boon to many (or at least a couple, for now) of us neophytes muddling our way through organic chemistry in the hopes of reaching a sustainable alternative to store bought, and industry produced chelated products...and are naive enough to try, but wish to do so in an informed manner to better ensure hope of success...

(was that last bit a little too brown nosey)?



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