Hey all –
About to start cooking my super soil and I’m realizing I’m lacking on the K in my NPK – I’ve got bone meal, kelp meal, azomite, crab shell meal, earthworm castings, and some chicken shit from my coop that have cooked down over time. I just finished burning a bunch of trees from my property – is wood ash really enough for the plant throughout flower? My only option I can see off amazon is langbeinite – and if I have to order that, no worries. But are there any other options for me to up my K levels?
Thanks DGC!
The kelp meal you already have has some potassium. Composts, alfalfa meal, hardwood ashes, granite and greensand are also good sources. How they affect your soils pH is another concern. Especially the wood ash. Wood ashes can be quite acidic so be careful using too much as it can affect the soil’s pH balance. Kelp is fairly alkaline and can help restore balance along with your calcium sources. Potash from organic matter like composts, kelp and alfalfa break down and become plant available fairly quick and can be washed out of your soil as potash is highly soluble. While minerals like greensand and granite will provide a slower release over time as they can take longer to break down. Langbeinite is another mineral that’s very high in potash and is a great top dress if your soil is lacking and has a neutral pH. Langbeinite is fairly water soluble compared to other minerals with potash.
So what do you think should be my move for a long term increase in K in the soil? I probably will use some wood ash, but the greensand is in stock at my local hydro store so maybe that’s my answer.
Just trying to knock around a few ideas!
Greensand is slow release and a good long term solution as would be granite. Wood ash and bio char are also a good idea and will improve soil structure as well.
Potassium sulfate is some what tolerated(as organic/mined rock) and both elements are vital in flower. It’s a 0-0-50 so a little goes a long way. A few buildasoil products contain it. But sounds like your doing good on the mix so far.
http://npk-industries.com/potassium.html
Mystro has this mostly nailed, for sure. I use kelp and langbeinite as to have multiple sources. One thing I noticed missing in the mix is oystershell. I saw crab meal, which has some calcium but not as much buffering compacity. I love oystershell flour and would not make a living soil mix without it. If you going to use the wood ash, which isn’t biochar, you need to use some oystershell. I think alfalfa is must add as well for the tricantinol and good amounts of N and K. I would opt for fish bone meal instead of just bone meal which has a much higher likely hood of being GMO sourced. Good luck, sounds like you will have a really nice mix.
Neem seed meal, Kelp meal and alfalfa meal are probably the best sources of potassium for our purposes.
Greensand isnt great in my opinion. Its typically very slow to release, and can sometimes come with heavy metal concerns.
I agree with the comment above about avoiding bone meal… It can be really hot and cause issues if you dont use it right, and its typically sourced from unpleasant places. Fish bonemeal is a better alternative, but should still be used very sparingly.
Keep in mind your goal should always be BALANCED soil. Its better off to start with a mild blend of thats balanced than to try to put too much stuff in it. If you try to cram too much nutrition in there at once you will only cause problems. You can always add nutrition later through topdressing.
I wrote a few articles for the DGC about making your own soil that covers a lot of this stuff in more depth. check em out! you’ll find them here:
https://growerslove.com/pages/classic-soup-articles