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If you have something like mycorrhizae in your soil mix the mkp will likely reduce or kill it off from too much phosphate being added. If you put too much and don't flush it out either you could be in for some harsh herbs at the end. Consider than most bone meal will take around 6-10 (edited didn't put time frame, was supposed to be weeks) to become broken down, you could consider a top dress of bone meal when you are a week or two from flower to have it become available at your preferred time, if you reuse your soil or no till, calphos is a great product but usually takes a year or more to become sufficiently broken down and available for the plant to use, consider it an investment into your soil for future use, the micronized version is available faster than the granular but still takes time to become available (last I remember from commercial organics grower who did the testing on plants said it was something like 3-6 months depending on irrigation, temperatures etc versus the 12-18 months, but this was just a small portion available where you start to see it becoming more available.)
I don't think many of you guys have investigated the decomposition rates of the organic inputs being suggested here. I agree, it would be cool to use organic inputs that fully breakdown/decompose in 6-10 days...problem is, I am not aware of any; synthetics breakdown fast and organics are supposed to breakdown slower.
I found this chart from OSU very helpful (4th article on this webpage). https://smallfarms.oregonstate.edu/calculator/research-background
According to this chart, after 7 days bone meal is only 49% decomposed/broken down and after 28 days only 59%...100% occurs around day 70 or so (according to that study). On a separate track, notice the Plant Available Nitrogen (PAN) levels at 28 days...very interesting that kelp meal is a negative 6% (it consumed more nitrogen than it created).
I found this chart from OSU very helpful (4th article on this webpage). https://smallfarms.oregonstate.edu/calculator/research-background
According to this chart, after 7 days bone meal is only 49% decomposed/broken down and after 28 days only 59%...100% occurs around day 70 or so (according to that study). On a separate track, notice the Plant Available Nitrogen (PAN) levels at 28 days...very interesting that kelp meal is a negative 6% (it consumed more nitrogen than it created).
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I'm certainly not faulting anybody for doing the same thing I once did as far as mixing and matching. We are all here to learn.
However there does need to be a distinction between organic and chemically grown, even if it is a faulty definition. Especially if you're marketing a product.
With much respect for all...
Then use synthetics.
Let's say you mixed kelp at (-6%) with perhaps blood meal at (+66%), I'm not sure that I could assume a rate of (+30%) or not but I think it illustrates my point.
I know it takes a little effort to compost it all. A worm bin doesn't take a lot of room. I know, time is money, we're in a hurry. No argument. Do what you feel you must.
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Guest
Good chart. I have seen references about P and K as well but dont have handy links at the moment. I have a batch of soil thats been mixed since march and in the last month or so I have added about 2-3 cups per CF more of gypsom (thanks to slownickle) and a week before putting it in pots added about another half cup per CF of steamed bone meal. Transplanted seedlings into it a few days ago.
Im hoping for pretty much a top dress only grow of ground MBP, Kelp meal, some more gypsum.
But Im going to have some MPK powder https://www.ebay.com/itm/190892240179 on hand. Hope I dont need it. Better to have and not need,,,
No reason to be snitty because we take different paths to the same destination.
But now you are thinking about a concept I have studied for more years than I want to count, lol...what is the Plant Available of a particular nutrient/mineral/input?
And then there are those peculiarities/benefits of certain "meals". Example, excellent source for amino acids is Soybean Meal and nothing beats Linseed Meal for a source for lignin and phenolic compounds that act as chelators. Of course I can go on and on, but since I use a teensy weensy bit of MPK....who cares? Right?....lol.
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Guest
Without getting to far off topic or offending the purists I wonder how many organic purists, no insult ment, use RO water that is wasteful of the raw water needed to purge the minerals and chemicals from tap water? My tap water has a crazy alkalinity level so I use a whole house RO filter that feeds my freezer for ice and a tap at the kitchen sink. I jug it up for all my house plants including the crop. The taste difference is obvious.
Life is full of what some people call compromises. I for one think there is no absolute black and white.
I wouldn't quite put it that way, but that's kind of the gist of it.
I'm not a purist. I try to use natural and organic methods, but I make no claims. I can't claim that everything that I use for compost or meals come from organic sources. Sustainability takes the front seat to organics in my opinion.
I just don't have a need for that stuff. I once thought I did...
And as one's garden matures, one discovers they need stuff...they never knew they needed.
The ingredients for my topdressing used to be 2 maybe 3 inputs, now there are 9 (all OMRI/organic) and each has specific role/job:
Jamaican Bat Guano (1-10-0)
Neem Seed Meal (6-1-2)
Feather Meal (12-0-0)
Linseed Meal (6-1-1)
Soybean Meal (7-1-2)
Indonesian Bat Guano (0-7-0)
Blood Meal (12-0-0)
Potassium Sulfate fines (0-0-50)
Rock Dust (0-0-0)
The Potassium Sulfate helps balance the desired PK ratios and I grind to a powder the first 5 items in a coffee grinder. The smaller the particle, the faster it breaks down/decomposes.
The best technique for topdressing I discovered is to mix a few cups of grow medium with the topdressing before scratching it in...and then drench the container with 2x the normal amount of liquid (I let the runoff sit for a day or so). Wetting/soaking the combination of topdressing + grow medium seemed to have eliminated the normal caking/build up of nutrients that once sat on the surface top as they slowly/partially broke down. IMO...this also was wasteful since so much of the topdressing was not being used by the plant.
A side benefit (pun intended) of adding a few cups grow medium to the topdressing before scratching it in are the appearances of new root growth shooting upwards towards the surface top...an observation I did not see when I scratched in the topdressing with nutrients without the addition of fresh grow medium.
When do I topdress? The day I flip 12/12. Based on studies by OSU and others, I guestimate all goodness from my topdressing will be consumed/expired/all used/bye-bye around day 70...about the time for harvest.
Adding teensy weensy bit of MPK strategically a few weeks before harvest does bless me with a 10-20% bump in quantity without sacrificing quality. I harvest every 8 days (about 45 harvests per year) and have been doing it this way for over 15 years now.
And yes, I reclaim my soil using both organic and biodynamic principles. This is my 7th year of reclaiming grow medium--and every year I invariably will roll in a new item--this year I am revisiting biochar...this time I am mixing it with Malibu Compost at the rate of 10% (not 50%).
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