somerandom
Member
If I'm adding powdered dolomite to my soil , should i stop adding liquid cal/mag in the feeding ? I wonder what cal/mag toxicity looks like . i have had some yellow turning leaves with blue spots .
2 Tbs. per gallon sounds really high, most mixes call for just one.
Look up chlorosis and high pH.
Thanks for that . I will check run off PH next time i water . I use dolomite because it's cheap and readily available . Seems i may not have to be using it at all .Hmmm, soil test? What is the grow medium's PH? Meters, test strips or liquid vials & the color chart--lots of ways to find out.
BTW, dolomite is not the only liming agent available--oyster/crab shells, wood ash, calcite, hydrated dolomite...are a few, but they are not created equal. The CCE (Calcium Carbonate Equivalent)--or acid neutralizing capacities for liming agents are all different. Calcite (the baseline for all liming agents) is 100, dolomite is 109, wood ash is 80 or less, hydrated dolomite is 166, and most shells range between 75-90. Sooo...it not always "how much to add", but "what to add"...in addition to how fine/coarse the liming material is (fine material neutralizes faster than coarse material).
Me...I jack up the PH to 6.5-7 when I make my soil, and by the time the plants are harvested the PH will range 6.0-6.5...got to allow the natural PH decline for expired/spent grow mediums. I don't use Cal-Mag, rather my magnesium supplements are magnesium sulfate (epsom salts) and food grade DE (Fossil Shell Flour)...my custom grow medium is already rich in calcium.
Cheers!
Regarding the EC meter, there is only one calibration, but to get to PPM (parts per million) there are various scales that apply a factor to the EC reading. There is .5, .64, and .7. All of the meters actually read EC in their internal circuitry, but the readout may have one of the factors applied to arrive at whatever the "local" standard is for PPM, or whatever scale that particular manufacturer likes to use in their instruments. It is easier to simply use EC.
For example, an EC reading of 1.0 will be multiplied by 1000 and then the factor is applied. So if you are in Europe, an EC of 1.0=1000*.64=640ppm. If you are using a US-made meter, .7 is the most common factor, so the EC of 1.0=1000*.7=700ppm, and if the meter happens to use the .5 scale then the EC of 1.0=1000*.5=500ppm.
If you aren't thoroughly lost by now, the EC of 1.0 which the meter actually read was converted to 640, 700, or 500. To avoid the confusion of trying to figure out which scale your meter is, or what scale the fellow's meter is that you are asking questions, it is a lot simpler if everyone just uses EC.
Dolomite lime, ph, EC, PPM???????????? WTF happened to my forum?
Did we go back to the stone ages here?
Geez!
V
Will do , I'll also check the run off PH next time i water . I water/feed @ 6.5 . I'm not so much worried about the PH , it's my understanding that the dolomite won't allow it to raise above 7.0 . I'm just wondering if they are getting to much cal/mag .