This isn't one of those just do the math type scenarios...you really need to know what the pH is to start with when working with such large quantities of soil.
However:
If you are using 1 cup per cubic foot:
1 Cubic Foot = 6.42851159 Gallons (dry)
3,000 gal / 6.43 gal = 466.56 cu ft.
1 cup of limestone is .73 pounds
466.56 cups x 0.73 lbs = 340.59 lbs of lime
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It should be noted - the 1 cup per cu. ft. is a ratio used for peat based mediums.
I would not just amend "soil" with that much limestone WITHOUT getting a proper soil test and getting an accurate figure of how much lime you need to balance the pH of your soil.
Lime should not be considered the primary supplier of Ca or Mg - it's primary purpose is pH adjustment.
Without actually knowing the current pH of your soil - or if in fact you are actually using soil, ie DIRT, or a peat based medium, or purchased bagged soil, etc. Some peat mixes like pro-mix are already limed for proper pH balance as are most designer bagged soils, which are more often than not, mixed media and not simply "soil".
- HOWEVER - if you are working with a base peat moss and EWC combo that has nothing else in it at all...and you are not using a single soil bed, but splitting this mix into multiple large planters or smaller separate beds - you should be fine with the math at the top.
dank.Frank
looks like N and P deficiency to me...or else you wouldn't be the neon yellow in the leaves and the purple in the veins and petioles - just look underfed.
dank.Frank
Well, look at the plant - it doesn't tell lies...
How much soil are you mixing at a time? How big is the container they are in currently?
dank.Frank
I think you just have a case of hardwater, a good chunk of those dissolved solids is likely lime. With the addition of all those liming or calcium heavy ammendents ( Fish bone, calphos, crab shell, potash, crushed dolo) - your a bit overlimed.
Watch the calcium imputs and try and collect some rainwater.
@ Highsen - the soil mixes made by fox farm already have lime in them for proper pH balance.
If you are using RO water - it should basically be pH neutral to begin with. I'm gathering the addition "CaliMagic" is causing the drop in pH?
Have you tried letting the soil mix buffer the pH already and it was unsuccessful? Or have you just been adjusting pH the entire time?
I'd suggest looking at this issue a bit differently; not as a how do I control pH - but rather how do I provide enough Ca/Mg so that I no longer need to supplement it. By doing this you eliminate the need to pH the water in the first place...
dank.Frank
For this crop there isn't too much you can do. Get better water.
If you want to depart from a strict LOS paradigm there are a couple of things i could suggest. Still organic.
Citric acid injection for one, low molecular weight organic acids may have the ability to solubilize P in soil. Plants use a range of these acids to modify rhizosphere ph, solubilize minerals and regulate soil ecosystem dynamics(?). Fun fact, most plants ability to grow in calcareous soils is limited by its ability to produce these acids. Using these acids will interfere with soil ecosystem dynamics to an unknown extent.
Low levels of soluble K in flower have helped me quite a bit. I feed them a tablespoon of molasses with 2-3 ml of strong kelp FPE / 5 gallons of (Ph'd) water as needed. The molasses has some Mag and trace also.
Next reamend cut it with some unlimed peat, ewc, aeration, and watch the animal based amendments. Bone and shell meals are loaded with calcium carbonate.
Long term it's best to just increase water quality. I'm collecting lots of rainwater at this point. RO for me will be a last resort. I'm considering some lower tech options like a peat or zeolite filter...