New mix....Lowering PH quickly ??

[Vas Deferens]

Hey Guys

I prepped a new mix about one month ago. First time I've created a mix. I'll do this is shovel loads rather than %'s if you'll kindly indulge me

4 x Organic compost
6 x Corse river sand
2 x Vermiculite
2 x Coco Peat
1 x Organic fertilizer ... http://www.katekfertilizers.com.au/Organic-Super-Growth.html

At first PH was off the scale, >10. It's coming down now, around 8, but I want to plant next week so want to use something to drop it asap, such as Aluminium Sulphate, but I'm worried about Al toxicity and I can't get an answer as to weather it's considered organic ? any advice or suggestions greatly appreciated

 

[briman]

aluminum sulfate at 4 grams per gallon of mix should set you up for success!:thumbs:

 

[Vas Deferens]

aluminum sulfate at 4 grams per gallon of mix should set you up for success!:thumbs:

Thanks Briman any worry of Al toxicity with MJ ? or is that only with blueberries and the like ? and, is it considered organic ? thanks brother

 

[A4]

I wouldn't use aluminum sulfate in your mix Vas Deferens and I have used and recommended it a lot in the past. After much reading on it, I highly discourage it. Basically the compound does reduce the soil pH but it does it by the process of the sulfate that is in the AS mixed with water. When combining sulfate with water it forms sulfuric acid, which acidifies the soil but only for brief periods of time. The aluminum itself is damaging to the root system and can build up in the plants, how much is debatable but my opinion is it should be left out of organic gardening.

What I would do is try and figure out why the pH is so high. Honestly, looking at your mix I am struggling to figure that one out. Peat is typical an acidic product, most composts are between 6 and 8 on the pH scale, river sand should not have a pH reading at all and from the looks of your fertilizer, it contains no lime although it does have gypsum. That leaves vermiculite which fluctuates but has been known to have a pH from 6 - 9.5. I would guess that the vermiculite may be the culprit although very little was used.

If it were me, I would do a slurry test on each of the materials and see what is causing your problems. Basically you need distilled water and a small container, like 100ml or something. Fill the container with the amendment to 100ml and put it into a jar you can seal, then fill the container with the distilled water to 100ml and put that into the jar with the amendment. Put the top on shake it well and let it settle for about 15 minutes and take a reading of the water. That will tell you the exact pH of that amendment.

After you have found the problem causing amendment, set out to find a replacement that isn't going to give you problems with pH.

 

[Vas Deferens]

I wouldn't use aluminum sulfate in your mix Vas Deferens and I have used and recommended it a lot in the past. After much reading on it, I highly discourage it. Basically the compound does reduce the soil pH but it does it by the process of the sulfate that is in the AS mixed with water. When combining sulfate with water it forms sulfuric acid, which acidifies the soil but only for brief periods of time. The aluminum itself is damaging to the root system and can build up in the plants, how much is debatable but my opinion is it should be left out of organic gardening. What I would do is try and figure out why the pH is so high. Honestly, looking at your mix I am struggling to figure that one out. Peat is typical an acidic product, most composts are between 6 and 8 on the pH scale, river sand should not have a pH reading at all and from the looks of your fertilizer, it contains no lime although it does have gypsum. That leaves vermiculite which fluctuates but has been known to have a pH from 6 - 9.5. I would guess that the vermiculite may be the culprit although very little was used.

If it were me, I would do a slurry test on each of the materials and see what is causing your problems. Basically you need distilled water and a small container, like 100ml or something. Fill the container with the amendment to 100ml and put it into a jar you can seal, then fill the container with the distilled water to 100ml and put that into the jar with the amendment. Put the top on shake it well and let it settle for about 15 minutes and take a reading of the water. That will tell you the exact pH of that amendment.

After you have found the problem causing amendment, set out to find a replacement that isn't going to give you problems with pH.

Thanks for your interesting comments A4. I am desperately trying to avoid using AS. I tested the components this morning, The vermiculite was at 10 and the compost was off the scale up around 13-14. I got the compost delivered in November, it was warm. The mix i want to use next week is averaging 9-10. I trialed one pot with AS as per Briman's ratio above (4g per Gal) and it landed at 6.5. I am now time critical as I have seeds cracked in jiffy pots and will need to go in next week to avoid stunting. SO, I am thinking, a minimal use of AS to get near the zone and the new mix should correct as the fert breaks down and I give it compost tea & worm juice treatments ? I'm caught between a rock and a hard place. Thanks Briman and A4

 

[Mr Piggy]

Honestly in a mixed organic soil there is no quick fix. Patience is the game. I would add a couple of cups of dolomite lime to the mix and check the PH after two-three weeks of cooking. I'm also worried about all of that sand in the mix, I think that much sand may muck things up a bit.

The reason I push the time and DM lime method is once it levels out it is very stable, and the DM lime is a great slow release source of calcium and magnesium, the two macro nutes that are almost always neglected.

 

[Vas Deferens]

Thanks Piggy , just wondering what problems do you envisage with the high sand % ? certainly won't be drainage lol

 

[A4]

I can't speak for Mr Pig, but I can tell you one problem that I wouldn't like at all and that is lowering your CEC. Your cation exchange ratio(CEC) is the total number of cations a soil can hold, or its total negative charge. The higher the CEC, the higher the negative charge and the more cations that can be held. The more cations that can be held, the more nutrients that can held held in your soil and the better buffering ability of your soil to pH changes.

 

[Vas Deferens]

Thanks for the opinions guys, much appreciate the food for thought and the learning that AFN provides, love it ! Anyone, please feel free to comment. I got this mix from an experienced old grower. I personally wouldn't have mixed that much sand in myself either but he was pushing the drainage point so i went with his advice.

 

[Vas Deferens]

I can't speak for Mr Pig, but I can tell you one problem that I wouldn't like at all and that is lowering your CEC. Your cation exchange ratio(CEC) is the total number of cations a soil can hold, or its total negative charge. The higher the CEC, the higher the negative charge and the more cations that can be held. The more cations that can be held, the more nutrients that can held held in your soil and the better buffering ability of your soil to pH changes.

Hi A4,

I'd never heard of CEC, THANK YOU ! I'll do some research on it tonight