Oyster shell flour redundant with rock phosphate? / Critique my planned soil inputs

Reverend Budbreath

Reverend Budbreath

Red-eyed and mystified
Hey guys, I'm having tons of fun researching and planning my soil recycling and amendment project that I will do on the soil I'm currently growing in (approx 30 gallons volume - it's six 7-gal pots, but the actual amount of soil that filled them turned out to be only 4.5 cu ft/29 or 30 gals).

But I'm stuck at one place: is oyster shell flour unnecessary if you already plan to have rock phosphate? They both provide calcium (and phosphorus, in the case of the rock phosphate). Would having both in there throw too much Ca into the mix?

For that matter, is having both rock phosphate and basalt rock dust another redundancy?

In fact, let me share my sketched plans as they look right now and see if any soil gurus have comments.

Here's the list currently that I want to amend with:

Biochar
Vermicompost
Oyster shell flour
Down To Earth's Bio-Live (combines alfalfa, kelp, beneficials and marine inputs)
Neem/karanja seed meal
Insect frass
K-Mag (killer sulfur and potassium input by KIS Organics)
Rock phosphate
Greensand
Basalt rock dust
Coco coir
Perlite
Wet down with more beneficials (via Mikrobs Microbial Superpack) and allowed to "stew" in a tub for a couple weeks sitting on a large heat mat


Here are the amounts my research so far suggests I should use on 30 gallon volume:

Biochar: 10% of soil volume (3 gallons biochar)
Vermicompost: 10% of soil volume (3 gals) (10-qt bag of Terra Vesco vermicompost)
Oyster shell flour: 1 cup per 6.8 gallons (do 4 cups)
Bio-Live: One 5-lb box
Neem/karanja blend seed meal: 0.25 cup per gallon of soil (7 cups)
Insect frass: Use 1% by volume, so for ~30 gallons of soil, use 5 cups
K-Mag: Unknown as yet
Rock phosphate: (unknown... question of overkill if oyster used also)
Greensand: 2 tablespoons per gallon of soil
Basalt dust: 0.25 cup per gallon of soil (7.5 cups)
Coco coir: 10% of soil volume (3 gals of coco)
Perlite: Around 5%, so 1.5 gallons

Your thoughts? I'd appreciate some feedback.​
 
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The mouse isn't one much for measuring stuff for dirt. But, i would use the oyster shell alone, simply because that is what is handy, here. After reading and repeating a 'too hot' soil mix, i would tend toward going lighter on any recipe, just because of the plants and others that were burnt by the recipe. BUT, that being said, after going light, i would watch for deficiencies, add a LITTLE bit more oyster and hand water that in, if needed.

gosh , i hope that someone who knows what they are doing will give you a better answer.
 
Hi RevBB, hope all is well. Are you just starting your living soil adventure? If youre just getting started, I suggest reading Teaming with Microbes (I can email you a pdf copy if you dont want to get the book), it will help you understand whats going on in the soil. Then when you are really ready to dive into the rabbit hole, look up Dr Elaine Ingham. I'm no expert, but I'll share the information I can remember and hopefully that helps.

Oyster shell vs rock phosphate (aka calphos and soft rock phosphate) - From my understanding oyster is used to replace dolomite lime because its calcium carbonate also and the microbes love it. Does it break down faster than lime, I dont know, but the only way to know for yourself with a lot of the soil theories is to get a microscope and see for yourself. I do not believe using oyster shell and calphos would be detrimental. Even if you used recommended amounts, hell or even doubled them, and used both, I dont believe you would risk having too much calcium.

Biochar - if you can, make it yourself. Its one of the latest old as shit new things that can get expensive. Youtube has videos on how to burn wood, oops I men make biochar. LOL!

From my understanding basalt is an alternative to azomite for trace minerals, not used for a macro nutrient like phosphorus.

Greensand is used to break up clay soil, I've read more than once it takes forever to break down and its not water soluble. You probably dont need it.

Be careful with the neem, read it can be hard on young plants if its not finished decomposing. Look for literature from Clackamas Coot about this, really all of soil building. He's THE Guru about it.

If youre adding coir, I would probably add the same amount in perlite. I switched to coir a couple grows ago and most if not all of the mixes using coir and perlite have them at equal amounts. Coir holds a lot of water until the plant is big enough to dry it out everyday.

Also, I get the excitement and all that about mixing your own nutrients, but if you dont necessarily have to do it yourself, I would check out buildasoils website and probably just get the premixed nutrient packs they offer. They have Coot premixes available. I would still add the biochar and EWC, but everything else might be in the coot mix.

Regarding how long you let the mix sit before you use it, well, back when subcool took vic highs supersoil mix and started making it popular, the standard wait time was 8 weeks. Over time, that wait period got shorter and shorter, and people thought it was black magic that they were burning their plants, not taking into consideration they were impatient. I think this is your first soil mix, so this is whats going to happen. Have you ever made compost? Same thing is about to happen. You're going to amend your soil, wet it with EWC tea and then cover it. The next day your going to check it and notice its way hotter and a good amount of condensation forming in the container. Thats good, mix it up and keep doing that say every day or every couple days until it stops getting hot. It takes time for the reactions to stop happening, theres a reason in agriculture they say amend in the Fall for the Spring garden.
 
Hey digger, thanks for the detailed response. I hope all's well at your place too. I am just getting started in this direction, yes, but I've been researching the subject a lot so I'm not coming into it totally green. I've grown in soil many times of course, but never with an acute awareness of the biology as I'm trying to do now. I have a decent understanding of soil biology. I've seen all the praise for Ms. Ingham and I've also heard dissenting voices about her. Strange as it may sound, when I notice that nearly everyone points to one person as the unassailable expert on something, my reaction is to look elsewhere to get a broader spread of opinion. Just a quirk of my psychology I guess.

My main question to you is, which among the amendments I named would be "hot enough" to burn? Maybe the neem/karanja seed meal, I can see that, but anything else? I'm consciously staying away from animal products like blood, bone, guanos, and manure. I know alfalfa can burn if too much is used, but I'm not adding a huge hit of that (only whatever's in the "Bio-Live", which is not a lot I suspect). I've read that 2-3 weeks is enough for a mix like this that doesn't contain hot raw stuff that needs months of breakdown, but obviously I don't really know. And I won't be able to give it much more than a 2-week "cook."

Interesting what you said about greensand... but that would actually be the point of including it—that it takes a long time to break down and will start paying off in future grows, not the first grow after putting it in. (I guess that accumulation would also be a good argument for not putting more in at every remix.) I didn't make it real clear in the original post, but what I'm talking about doing is repeatedly amending and reusing the same base soil, which is Ocean Forest, between grows. I'm in a situation where I have to be discreet and I don't want to be periodically hauling more bags of soil into the garage at every new grow. Plus, I don't believe in using soil once and then tossing it. It feels wrong to me on a few different levels. One, it feels like a waste of money. Second, if efforts have been made to create a healthy soil microherd during the grow, then that will all be tossed out and wasted if the soil is discarded. Third, I don't have a truck or friends with trucks or any viable way to get rid of all the soil even if I wanted to! So this way makes a lot of sense for my situation.

Regarding your comment about using a pre-made blend, I guess you'd have to know me better to know that the doing it myself and all the research and mental gymnastics and planning is where a lot of the joy is for me in it. All the planning and thinking... that's where the fun is (and the growing itself is fun too). This is like cooking for me... there's an artistic or artisinal aspect to it. Just using another guy's idea of what is a good mix, even if it works great, doesn't get me off. I don't enjoy the physical mixing in a tarp and all that very much. It's just a necessary step. It's conceiving the whole thing that I like, and then—hopefully—having it all work out pretty well because of the research prior to doing it.
 
nannymouse said:
The mouse isn't one much for measuring stuff for dirt. But, i would use the oyster shell alone, simply because that is what is handy, here. After reading and repeating a 'too hot' soil mix, i would tend toward going lighter on any recipe, just because of the plants and others that were burnt by the recipe. BUT, that being said, after going light, i would watch for deficiencies, add a LITTLE bit more oyster and hand water that in, if needed.

gosh , i hope that someone who knows what they are doing will give you a better answer.
Click to expand...

Thanks nannymouse. It's a journey, and I've just started out on it... I hope it goes well because if I screw it up, I'll probably run back to hydro or coco, though those aren't bad options at all, just different from where I'm trying to go for now.
 
nannymouse said:
The mouse isn't one much for measuring stuff for dirt. But, i would use the oyster shell alone, simply because that is what is handy, here. After reading and repeating a 'too hot' soil mix, i would tend toward going lighter on any recipe, just because of the plants and others that were burnt by the recipe. BUT, that being said, after going light, i would watch for deficiencies, add a LITTLE bit more oyster and hand water that in, if needed.

gosh , i hope that someone who knows what they are doing will give you a better answer.
Click to expand...
I have a feeling I'm going to dig @nannymouse work and style. One thing to keep in mind will be relative breakdown rate. The flour or meal will typically be more bioavailable sooner than rock phosphate. It is also more sustainable long term to use meals or flours, worldwide we are facing a phosphorous shortage and I would anticipate prices increasing over the next few years. Pelletized chicken later or manure compost is another source for phosphorous that can be pretty cheap to order and could make your soil mix a little less intensive.

Those are just suggestions! If your system is working great the way it is, keep it up! If rock phosphate becomes scarcer and more expensive as expected, its nice to have some back up options!
 
You have to take into consideration the mineral contents of all those ingredients. This is not a KISS mix, and you are certainly guessing on at least a few of these. Firstly, what is the source of the biochar? Wood? Green waste? Coconuts? Biochar varies greatly in pH and mineral content, based on what the input product that was burned. It is more than just a source of carbon, but more than likely metals too.

If coco is your base media you are building on, you will want to make sure that coco is well rinsed of sodium first. And then you can buffer it further with your calciums of choice, preferably more than one source, and in recycled soil, preferably a mostly insoluble source.

You won't need much oyster shell if you are using coco as your base. Oyster shell is basically calcium carbonate and is a fair 1:1 replacement for lime. Chunky oystershell will actually take longer to breakdown that powdered lime. Its a good product, but will make a coco based soil very alkaline if overused. Calphos is calcium phosphate, which is a very good mostly insoluble source of phosphorus. I would add that too, but coco has a high anion exchange capacity and can naturally hold a ton of phosphorus, so you may need to experiement.

Coco also has a ton of potassium in it, and so does most vermicompost, and often times so does biochar. Biolive has a good bit of K (and probably enough N to start things off). Greensand and K-Mag will both have excess K that you don't really need, especially in early root growth. You are better off waiting to see how the plants do and top dressing as needed later.

I would also think that your vermicompost, frass, and bio-live additions will have enough nitrogen to start your grow. Adding any other sources like neem or karanja meal could hurt your plants. I would also hold off on those, and top dress later if needed.

Best to mix your base mix first, without amendments, send off for a soil test, and see what is missing or is in excess.
 
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