[Floyd]

Good day all

After reading the Pinned RockDust thread here I am sold on adding RockDust for my next grow.

Could someone answer me this if possible please?... Would adding RockDust eliminate the need of Dolomite Lime or CalMg?
It seem's to me It would but I would like a definitive answer if possible.

I have sourced Crushed Basalt Rock Dust from a local Horticultural centre that is quarried close to home.
After being in contact with them they are prepared to supply me with the very fine RockDust they normally incorporate with courser RockDust (offering customers a blend of fast acting with some longer term material too).
I don't need long term, so I am chuffed they will supply the fine dust.

Living in a soft water area, I need Dolomite Lime or CalMg added to my compost or water, to avoid deficiency's and to allow the compost to naturally buffer the water.



The one I have sourced locally is this:

Revive Volcanic Minerals - Crushed Basalt Rock Dust

"Minerals – crushed basalt rock dust. We use crushed rock [which incidentally is a waste product at the quarry & would otherwise go to landfill] for incorporating into soils and growing media. This ‘organic’ basalt igneous rock which contains olivine, feldspar and augite is rich in natural plant nutrients (particularly, but not only potassium [K], magnesium [Mg], calcium [Ca], iron [Fe] and sodium [Na]). Although not traditionally recognised as a plant nutrient, silicon [Si] is also present in generous levels. The availability of Silicon to plants has been proven to reduce the incidence of disease in crops. We have analysed our rock dust to ensure that levels of toxic heavy metals are extremely low and therefore 100% safe to use for ornamentals and food crops alike. We have looked at rock from many different quarries had them analysed and we use the best and most consistent product known to us.

Olivine [(Mg, Fe)2SiO4], which is magnesium & iron rich, is unstable and therefore breaks down and releases its nutrients. Feldspar, rich in calcium & silicon, breakdown into clay particles releasing calcium which is essential for cell structure within plants. The clay that is formed during the breakdown of feldspar helps nutrient buffering and improves cation exchange capacity [CEC] of the soil/growing media. Improved CEC enables more efficient use of essential nutrient by the plant. Augite [(Ca, Na)(Mg, Fe, Al)(Al, Si)2 O6] is rich in magnesium, calcium and iron, another essential plant nutrient used in the production of chlorophyll [the green colour in leaves].

The rock dust when applied to the soil slowly breaks down with the action of weather and microbial activity and releases its nutrient to the soil thus making them available to the plants. It is also noticeable that worms and soil fauna appear to seek out this rock dust and are themselves more active when these minerals are present. This has a double benefit in that firstly the nutrients are released from the rock for the plants benefit, but also the soil/growing media becomes active with soil fauna offering even greater richness to the soil and improves plant health. The active soil fauna, microscopic creatures and beneficial fungi, not only work on the Rock Dust releasing its ‘goodies’, but also work the soil/growing media, releasing nutrients that are inherent in the soil, but otherwise unavailable [locked up] to plants. These beneficial microbes also colonise plant roots enabling better uptake of nutrients, improving plant vigour and effectively increase the plants resistance to damage from pest and disease attack."


Anyone one's wisdom one the matter would be much appreciated.


GF

[cheezychong]

Wow what alot of info, been using it on the girls,
the garden, and flung aload around our shared allotment
for a couple of years- Amazing stuff m8.

Tiz all about the taste.....

[MED]

i think its safe to add both rockdust and dolomite lime. sure ive seen custom soils with both.

[Gumbo]

Not sure if this helps or if it's old hat now but this is Subcool's 2010 revised recipe for his supersoil.In the US I think they call rock dust Azomite(A-Z of minerals and trace elements):


Here are the amounts we have found that produce the best tasting buds and strongest medicines:

8 large bags of high quality organic potting soil with coco and Mycorrhizae
25-50 lbs. of organic worm castings
5 lbs. of Blood meal 12-0-0
5 lbs. Bat guano 0-5-0
5 lbs. Fish Bone Meal 3-16-0
¾ cup Epsom salt
1 cup Sweet lime (Dolomite)
½ cup Azomite ( Trace element)
2 Tbs. powdered Humic acid
*** If using an RO system add in 1/2 cup powdered Cal/mag

I've also got Seers' own lab analysis on exactly what their dust contains if anyone needs,not that that's relevant here.Have recently been pissing around with my compostumbler trying to make a compost from horse manure and my lawn scarification rakings(mainly moss),rock dust and humic acid,my theory being that it will already have loads of worm casts in it and might already be very active herd wise without the need to mix my soil and leave a month to activate.Been a very steep learning curve though,but hey,it's fun.

Good luck with it GF.

Gumbo

[Green dazzler]

Both rock dust and dolomite lime raise the ph of the soil and affect the calcium/magnesium ratio.
Its certainly possible to over do it with either.
Pinetum dont recommend adding lime with rockdust. I did on my last soil mix then discovered my ph was above 7.5 which is not ideal at all.

[-=DrGreenThumb=-]

Seactiv Calcified Seaweed say's the Calcium oxide it contains works in the same way dolomite lime does, might want to have a look of that mate.

ETA: ow maybe that's not what your after, I'm stoned sorry

This post has been edited by -=DrGreenThumb=-: 15 April 2012 - 11:35 PM

[oldtimer1]

While you may need more free calcium and Mg if your water is free of them, I would suggest using products like Cal-Mag with soil or compost growing is a bad idea, while it provide a calcium and magnesium chemical salt solution, it is very likely to damage the micro heard, it is fine in water culture, Cal-Mag can be used as a quick fix, by folia application to tomato showing blossom end rot and apple trees with bitter pit, where there is not enough Ca available in the soil, the real answer is to get the soil right with adequate supplies of calcium, magnesium and iron available.

The product offered by angus horticulture appears to be a good one, but I have not tried it myself, how good it is for compost growing depends on how fine it is ground, you want dust not grit, seers has a blend of grain sizes which is fine for garden soil as it gives both short and long term release of minerals, but needs putting through a fine sieve before adding to compost.

If your problem really is a shortage Ca and possibly Mg think I would just add a desert spoon of dolomite lime [not garden lime] to each 10 litres of compost, I find the idea that the compost you use does not have sufficient calcium and magnesium already in it most strange. Most composts should have enough in them, as no one would be able to grow tomatoes, peppers and other Ca greedy crops using tap water in your area, In the past I have grown in many types of compost useing a softener and then Ro water at zero Cf useing biobizz and never seen a single problem with a lack of Ca or Mg, today I just use tap water and its hard, useing PM+ organic and don't have a problem with them either.

Adding rock dust on top of dolomite lime will not cause any problems, but rock dust and most soil microbes work better in a slightly acidic environment, ph 5.5 to 6.5 is best for them to break down the rock particles, so when adding rock dust to garden soil, liming at the same time is not recommended, the rock dust will gradually raise the soil ph profile, rock dust is not a good short term buffer or as quick as dolomite lime in action.

[MED]

top info OT1

so i should be fine to cut out my calmg then? 4 weeks flowering and using a high calcium nitrate calmg is making life a pain.

just hit them with bio-grow/bloom till the end?

[grandad]

a bag of rock dust has fine and course granuals, takes up to 3 months to break down the course, spraying once every month is a choice.

[Floyd]

greenfloyd thank's for everyones reply's on this thread.

oldtimer1, on 16 April 2012 - 08:40 AM, said:

While you may need more free calcium and Mg if your water is free of them, I would suggest using products like Cal-Mag with soil or compost growing is a bad idea, while it provide a calcium and magnesium chemical salt solution, it is very likely to damage the micro heard, it is fine in water culture, Cal-Mag can be used as a quick fix, by folia application to tomato showing blossom end rot and apple trees with bitter pit, where there is not enough Ca available in the soil, the real answer is to get the soil right with adequate supplies of calcium, magnesium and iron available.

The product offered by angus horticulture appears to be a good one, but I have not tried it myself, how good it is for compost growing depends on how fine it is ground, you want dust not grit, seers has a blend of grain sizes which is fine for garden soil as it gives both short and long term release of minerals, but needs putting through a fine sieve before adding to compost.

If your problem really is a shortage Ca and possibly Mg think I would just add a desert spoon of dolomite lime [not garden lime] to each 10 litres of compost, I find the idea that the compost you use does not have sufficient calcium and magnesium already in it most strange. Most composts should have enough in them, as no one would be able to grow tomatoes, peppers and other Ca greedy crops using tap water in your area, In the past I have grown in many types of compost useing a softener and then Ro water at zero Cf useing biobizz and never seen a single problem with a lack of Ca or Mg, today I just use tap water and its hard, useing PM+ organic and don't have a problem with them either.

Adding rock dust on top of dolomite lime will not cause any problems, but rock dust and most soil microbes work better in a slightly acidic environment, ph 5.5 to 6.5 is best for them to break down the rock particles, so when adding rock dust to garden soil, liming at the same time is not recommended, the rock dust will gradually raise the soil ph profile, rock dust is not a good short term buffer or as quick as dolomite lime in action.

Hello OT

Thank you for your indepth reply, and if I may take this opportunity to say, over the past 10 years searching for answers to countless questions,
your posts here at UK420 and the vast knowledge and experience you share within them has been, and still is, invaluable. Many thanks.

Regarding this topic of CalMg, Dolomite Lime and soft water, this is the one area of my growing that I am wrestling with, mainly the relationship Calcium has with water and PH,
and how it effects our plants.

My problem, as far as I am aware, is soft water. I live in Scotland and the water is around 40 ppm, which to my knowledge indicates low bi-carbonate levels which
usually coincides with low Ca in the water. Also as far as I can gather, there is an important relationship between Ca & K; also often but, by all means not always, Mg is low when Ca is low.




My (quite possibly wrong) understanding is that there would normally be enough Ca and Mg already in the compost to support our plants through there cycle, giving that the water was not soft.

MY compost is Plant Magic Supreme PH 6.5 and I use OT Grow & Bloom.

I have had clear Ca Deficiency that starts developing around week 3 from seed (before OT Grow)
I shouldn't be getting one with the compost I use and always question myself each time it occurs, but as soon as I supplement the water with a liquid CalMg the plants revert back to normal.
If needed, here is my thread on the last Ca Deficiency I encountered.

I do not like having to supplement my water, with a non organic product and I have a friend who has to do the same.
At first I believed my problem was lack of Ca in the water, leading to a lack of Ca in the plant. I now know this to be wrong now,
and I think it was related to how the Ca in the water effects the composts ability to buffer the water/feed.

Your post regarding PH Buffer was an insight as it highlighted a similar problem to myself.

You mention "composts such as Westlands MP + JI will buffer between ph5.5 and 6. As most of the uk has water with at least some carbonates the water at the rootzone will be ph 6, you can not tell this with run through, but by extracting water from the rootzone several hrs after watering. I have only come across one case where a member had problems, he came from Scotland and had soft water, he was getting odd lockout symptoms, treating the symptoms topically made no difference, I suggested sprinkling a little dolomite lime over the compost surface, and things came right in a few days, its pretty certain that prior to that the rootzone had gone to the lower buffer level and stayed there or even acidified lower."

The Dolomite Lime I have been offered from Angus Horticulture, just like the RockDust, is the very fine type that they normally combine with a coarser textured one.
So this Dolomite Lime should be a perfect replacement for the CalMg I currently use.


I would very much appreciate if you could tell me if you find time, what is the relationship between Ca, soft water, the composts beneficial micro heard and PH Buffering?
Why does the simple lack of Ca in the water, lead to such a problem when there is Ca already in the PH 6.5 compost, that would buffer normal or hard water sufficiently?
Also knowing the compost and Nutrients I use, do you think a RockDust and Dolomite Lime combination would be fine?


Kind regards

This post has been edited by GreenFloyd: 18 April 2012 - 09:45 PM

[MED]

bump

[oldtimer1]

How do you know the Plant Magic Supreme buffers to 6.5? It may lack sufficient free calcium carbonate for your water.

My comment about Westlands MP + JI will buffering between ph5.5 and 6, came from their own specification, they no longer give details about composts today, I used to use Westlands at the time, so I checked and found that the compost I had buffered at 5.7 so was in spec and worked just fine with my tap water, the last composts I used with Ro water that worked just fine were with the compost I used to make for myself and also Allmix.

If your water is free of calcium and magnesium your compost needs free calcium carbonate that will dissolve when you water, I don't know what PM+ use to balance their compost buffering levels. Most composts are buffered to deal with hard water, ie Arnie's favourite JAB + JI is quoted as 5.5 to 6.

Not many people have to deal with totally mineral free water, I would suggest if you are already in final pots adding a teaspoon of dolomite lime to the loosened surface of the rootball, then watering through. That should resolve immediate problems, without a water board report its hard to tell, are there are still problems with acid rain in your area, if your local water is forced from sphagnum bogs and there are large areas of conifer plantations its also possible that your tap water sources are quite acidic.

If thats the case I would rest the buffer of any compost you use to round the 6.5 to 6.8 level, this takes some time to verify and get right, as by mixing in lime to your compost it takes a few weeks to stabilise enough to an accurate reading.

[MED]

i havent been adding my calmag for the last 4/5 waters and they are doing just fine in all mix
i thought that might have been because i added plenty already :/

i live in the same neck of the woods as GreenFloyd. 42ppm at last count

was planing on moving to another soil after this grow so watching this closely.

top info OT1

[Floyd]

oldtimer1, on 25 April 2012 - 12:26 PM, said:

How do you know the Plant Magic Supreme buffers to 6.5? It may lack sufficient free calcium carbonate for your water.

My comment about Westlands MP + JI will buffering between ph5.5 and 6, came from their own specification, they no longer give details about composts today, I used to use Westlands at the time, so I checked and found that the compost I had buffered at 5.7 so was in spec and worked just fine with my tap water, the last composts I used with Ro water that worked just fine were with the compost I used to make for myself and also Allmix.

If your water is free of calcium and magnesium your compost needs free calcium carbonate that will dissolve when you water, I don't know what PM+ use to balance their compost buffering levels. Most composts are buffered to deal with hard water, ie Arnie's favourite JAB + JI is quoted as 5.5 to 6.

Thanks Ot1

I had read the PM+ Supreme was 6.5 on the site I buy it from but I went to double check this and they no longer list its PH.

I called Steve at Plant Magic and he was very helpful.

He said there last analytic report regarding the soil, stated the PH was 5.8.
So this would be geared more towards hard water if I am correct.

With the combination of pm soil with soft water, would my problem be that the PH is not being correctly buffered?

Rather than a lack of Cal reaching the plant being the problem,
is it the lack of Cal causing PH buffering problems?

Can I ask what soil/compost/mix you favour yourself Ot1?

[oldtimer1]

I'll quote below what I said about ph'ing compost recently, as I said about if I had very hard water ph 9 or above I would alter the compost a little to suit, I suspect you are right at the other end of the spectrum with very low ph low mineral content water that your compost has insufficient carbonated to buffer and supply enough Ca and Mg to meet your plants needs, in your position I would supplement the compost with dolomite lime, I would mix well and store for a period before use to let the reaction stabilise, I would also add rock dust at he same time as the lime.

I use PM's compost, I do add rock dust, I'm in a very different water situation to you in that it is a relatively hard water area in london with quite a lot of trace elements, since the water ring main round london was finished our water varies less than before and all the water supply is very much the same where ever you live in the city, I grabbed a thames water analysis for a north london area to give you an idea it will be pretty much the same all over london, I'll add it at the bottom, you should be able to get a similar report from your supplier giving analysis of your water.

Even though I add rock dust to my compost I never run into any lockout due to the buffer level rising over time, its not even been a problem when the compost has been reused several times.

I hope this helps Ot1.

oldtimer1, on 11 April 2012 - 09:58 AM, said:

I don’t understand why people try and apply the chemistry of dealing with a water medium [hydroponics] with a compost or soil medium, the buffering in water are carbonates or acids, to change it to a ph where all the dissolved nutrients are available to plant, means you have to reset the ph level to the best for water culture uptake.

Compost is made with a blend of acid and lime products to balance the compost PH level within a certain band ideal for most plants and keep it there.

Add water or a nutrient solution above or below that buffer point and the components slowly react until it brings the water in the saturated root ball back to the same point, this takes several hours, so the thing of I measured my run through, means absolutely nothing.

The horticultural industry produces hundreds of millions of plants every year, garden centres sell them, people take them home and grow them with no problem all using standard tap water.

Where I live depending on the time of the year my water varies between 7.6 and 8.4, I tested it for many years and my figures are very close to those published by my water board. I have never had a ph problem growing my cannabis or my vegetables, flowers etc, I have even reused my canna compost several times and not run into problems. It takes a very long time to alter soil or compost buffer levels.

Maybe if I lived in an area where the water board ph max/min bands were above ph 9 and if it caused a problem, I would not ph my water, its just to much faf, I would blend in a small percentage of ericaceous compost to my standard compost to lower the mixed compost buffer level a little.

Edit to add cannabis in soil or compost can take up nutrients in a much wider ph band than with hydro growing, you are in the hands of the compost makers as to where their buffer level is set.

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