Topdressing with Tennessee Brown Rock

Thinking about feeding my organic outdoor grow some extra phosphorus in anticipation of flowering, I decided to take a look at what I have on hand instead of going out and spending more money on fish bone meal. I decided to give Tennessee Brown Rock a try--have most of a 25# bag on hand, some of which I'd used as a soil amendment before transplanting into the ground in June.

In any case, I sprinkled some around the root zone of each plant and watered it in (it's a very find brown dust). Seemed to soak right in to the soil. Lots of phosphorus (27%) and calcium too, plus other trace minerals. Supposed to slow-release and extra won't bind up other nutrients.

Just curious if anyone else has tried this product as a topdressing for flowering. I'm thinking this may do the job nicely. Sounds like fish bone meal works well to but I've heard a few stories of animals attracted to the smell and digging up the roots.

organic phosphorus that is plant ready is very hard to come by, even though its a fine dust Idk if that will break down in time for the plant to use this season, usually azomite and other rock dusts usually take months... The few things that have ready phos for organics would be EWC, well aged composts.. Its definitely not a bad thing, hopefully they will get some use out of it, but just something to keep in mind for phos its something to add early and make sure theres enough before flower... also good mycorhizal fungi in your rootzone will help tremendously for getting nutes plant ready.

There are some liquid phosphorus that is plant ready but it is synthetic so if you want to stay organic only I would avoid.

But again, its a good thing to have in your soil, so recondition and reuse for next crop. Good luck.

I guess I could spring for some fish bone meal...supposedly that works well once the microorganisms in the soil break it down. From what I understand that's just a matter of weeks. Earth worm castings you say also? Could get my hands on some of that, too.

This description from a supplier seems to suggest TBR is available to plants quickly:

yeah I was just looking it up last night tbh, I was planning on adding something for an extra kick of P going into flower and thats what I was reading, basically ewc and compost are the only organic things I could add that would be plant ready, I added a ton before veg and top dressed another 200-lbs ewc or so, (a bathtub full of aged ewc along with thousands of fat worms in there) mixed across all my pots and I dont plan on adding the fish bone (did that during soil mix,) or and blood/bone/feather meal for top dress because I get raccoons around my yard and I dont want them digging this late, my soil mix had already been aged with the other fish bone meal so that should be plenty. I also regularly top dress with compost and ewc as well as feed ewc tea and compost teas all the time so that will have to be enough until harvest unless I see any deficiencies. Not taking any chances with critters digging up my roots especially without fencing around my whole plot only half. I plan on adding at the end of season mix when I go to cover crop and let it recondition for next year. Please let me know if you find anything else organic but like I said I was checking last night but only for about an hour or so
Good luck bro.

Heres an older looking chart with some organic phosphorus sources and a little description of their availability and how long they last.


Few more interesting links I was looking at last night:



https://www.ctahr.hawaii.edu/MauiSoil/c_nutrients02.aspx <--- Link is about phosphorus but this whole section of this website is awesome,
https://www.ctahr.hawaii.edu/MauiSoil/c_nutrients.aspx <--- here is the link for all of the essential nutrients first page.