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Lubdub

Soil selection for autos

33 posts in this topic

@Lubdub I'm not a soil expert, but do understand about coco's behaviour. Just be aware and do it normally to start, it may be ok, but be prepared to double it if you see deficiency issues. I say this because I don't want you to inadvertently overfeed if there is no issue. 

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Posted (edited)

21 hours ago, catweazle1 said:

If the coco wasn't buffered correctly before mixing, it may scavenge nutes out of the soil; that's why the need for doubling nutes.

Can you explain to me how coco (an inert substrate), can "scavenge" nutrients out of soil.

ive never heard of this before and do see how its possible?

Edited by badbillybob

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Posted (edited)

2 hours ago, badbillybob said:

Can you explain to me how coco (an inert substrate), can "scavenge" nutrients out of soil.

ive never heard of this before and do see how its possible?

Surely you've heard of cation exchange?

 

Quote

Coco Coir's Cation Exchange Capacity
Soil particles and organic matter have negative charges on their surfaces that attract cations. The total of these negative charges are collectively referred to as the CEC.

The CEC is significant in growing media because it is a measure of the quantity of nutrients the media is able to hold on to before nutrients start leaching out. Plants are able to access the cations attached to the cation exchange capacity.

Coco often has a CEC in the range of 90-100 meq/100 g of media. The CEC of coco is naturally loaded with potassium (K) and sodium (Na), with little or no calcium (Ca) or magnesium (Mg). These are the four cations that are most important when buffering coco.

The goal is to significantly lower the percentage of CEC sites that have K and Na on them and increase the percentage of CEC sites that have Ca and Mg attached. Potassium can be attached to up to around 40% of the sites and sodium can be attached to up to around 15% of the sites.

What Is Coco Buffering?
Buffering coco media is accomplished by exposing the cation exchange to a solution of water with a high concentration of the cations that are desired on the exchange sites—in this case, calcium or calcium and magnesium.

Because the cations on the exchange sites are held reasonably tight, washing coco does little to change the makeup of the cations on the exchange sites. The washing will change the EC but not the CEC. CEC sites have a preference for some cations over others.

If the cations of Ca, Mg, Na and K are all present in the solution at the same concentration, they will be adsorbed at different levels, with calcium and magnesium being adsorbed at double the rate as they both have a double-positive charge, while potassium and sodium have a single-positive charge (Ca++, Mg++, K+, Na+).

For example, many coco product manufacturers buffer their coco with 8 kg of calcium nitrate per cubic meter of coco. Calcium nitrate has a value of 19% calcium, which equals 1,520 g of Ca with almost no Mg, K or Na if the water is clean.

As the process commences, a high concentration of Ca molecules attaches to the media—as each Ca++ molecule is adsorbed, two molecules of K+ or Na+ are released because the Ca has a double-plus charge and K and Na are single-plus charges.

In the beginning, the exchange goes very quickly, but as the exchange continues, the concentration of the K and Na molecules released into the solution slows the exchange down and it will eventually come into equilibrium. The buffering process can be done in 10-15 minutes—the point at which the exchange slows down enough that the greater exchange is not worth the wait.

Some coco products have been buffered with a higher treatment of Ca and Mg concentration. This creates a lower K and Na percentage on the exchange and adds the benefit of Mg to the CEC. These more advanced buffering processes involve a much greater amount of time, but result in much lower K and Na levels on the exchange.

This essentially creates a better coco product from day one, ensuring all of a nutrient mix goes straight to the plant versus amending the coco’s CEC. Maximum Yield

TL:DR Unbuffered coco contains lots of undesirable potassium and sodium ions, which have charge +1. When you add nutes to unbuffered coco, the magnesium, calcium and iron ions (charge +2) displace the sodium and potassium ions in the coco, and are  thus removed/reduced from availability to the plants roots. This leads to the well-known Ca/Mg deficiency in coco, also you have an increase in the plant-available potassium and sodium in the nutes. It should be clear that if you put unbuffered coco in soil it will deplete the Ca/Mg/Fe levels in the soil, and also increase the K and Na levels. Hope that helps.  If anybody struggles with coco or coco/soil mix, this is likely the main reason why. This is why you get runoff ec numbers in coco lower than the ingoing feed ec. 

I'm trying fytocell media next, which has no cation exchange capacity. Will be interesting to compare to coco.

Edited by catweazle1
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i get the impression that the OP is fairly new to the game so he would be better advised to stick to soil mixes, rather than complicate matters.

and i disagreee with doubling the feeds when there is only 20% coco in the mix. 

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If your soil is compacting too much just press very lightly when potting up and water slowly with a rose head watering can or equivalent

 

That solved it for me :yep:

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Posted (edited)

1 hour ago, catweazle1 said:

TL:DR Unbuffered coco contains lots of undesirable potassium and sodium ions, which have charge +1. When you add nutes to unbuffered coco, the magnesium, calcium and iron ions (charge +2) displace the sodium and potassium ions in the coco, and are  thus removed/reduced from availability to the plants roots. This leads to the well-known Ca/Mg deficiency in coco, also you have an increase in the plant-available potassium and sodium in the nutes. It should be clear that if you put unbuffered coco in soil it will deplete the Ca/Mg/Fe levels in the soil, and also increase the K and Na levels. Hope that helps.  If anybody struggles with coco or coco/soil mix, this is likely the main reason why. This is why you get runoff ec numbers in coco lower than the ingoing feed ec. 

I'm trying fytocell media next, which has no cation exchange capacity. Will be interesting to compare to coco.

 

I like the idea of adding coco to the mix for faster growth - will definitely be reading up more on this and trying it at some point. 

Seeing as my current results with autos and soil are 'meh' at best - i'll try hone my skills a little further before throwing another spanner in the mix lol.

Cheers for the detailed response :yep:

 

19 minutes ago, badbillybob said:

i get the impression that the OP is fairly new to the game so he would be better advised to stick to soil mixes, rather than complicate matters.

and i disagreee with doubling the feeds when there is only 20% coco in the mix. 

 

Right you are bro, never thought about combining the two, intriguing idea but think i'll try the all mix next time around.

 

11 minutes ago, baked bean said:

If your soil is compacting too much just press very lightly when potting up and water slowly with a rose head watering can or equivalent

 

That solved it for me :yep:

 

I plant in final pot so no potting up in my methodology, not yet at least. 

My main issue was not adding perlite to my bio terra plus this grow, only just got my watering back on track after a couple of weeks of mayhem. Plants certainly look the part - surprised they haven't hermied yet... 

Edited by Lubdub
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36 minutes ago, badbillybob said:

 

 

i get the impression that the OP is fairly new to the game so he would be better advised to stick to soil mixes, rather than complicate matters.

and i disagreee with doubling the feeds when there is only 20% coco in the mix. 

I wouldn't either, but would buffer it myself.

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On 03/01/2022 at 10:25 AM, badbillybob said:

i used to use all mix,it was fine for autos

 

Did you add anything else to the soil before planting? More perlite or something?

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no, just straight out of the bag, there is perlite iin it already.

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On 02/01/2022 at 6:41 PM, Lubdub said:

My local grow shops have a few organic medium options and I'm trying to chose the best soil for the autoflowers I'll be growing this year.

 

So my options are:

Bio Terra Plus

Guanokalong Complete Mix

Biobizz All mix

Biobizz Light mix

Plagron All mix

Plagron Bat mix

Plagron Pro Mix

Plagron Royal Mix (this is the slow release fertiliser one)

 

 

I'm currently using Bio Terra Plus and everything was fine until I over watered and now I'm just playing catch up, really. I'm happy to use it again but next time I'll be adding some perlite to help with drainage.

 

As far as I understand autos are light feeders so perhaps something more towards the light mix or bat soils would be best pick?

 

Plagron Pro mix sounds good too but I've never used their stuff, any good?

 

LD

:spliff:

 

 

 

I've used Biobizz Light Mix and Plant Magic Soil Supreme for autos, both were alright and I couldn't notice a difference between the two. Clover MPC is highly recommended by a number of growers on here, it's cheaper than most of the options you listed above and there are quite a few auto grow diaries with it being used, I'll be using that in my next auto grow. 

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55 minutes ago, ricklepick said:

Clover MPC is highly recommended by a number of growers on here.

 

Yeah I've come across it but I'm not in the UK so shipping makes it quite pricy to send over..

Think it's between biobizz light and all mix. I guess the difference being feeding sooner and heavier with the light mix.

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3 hours ago, Lubdub said:

 

Yeah I've come across it but I'm not in the UK so shipping makes it quite pricy to send over..

Think it's between biobizz light and all mix. I guess the difference being feeding sooner and heavier with the light mix.

I didn't realize you weren't in the UK. I've had no issues with light mix, I grow in 4.5 litre/1 gallon fabric pots with seeds germinating in root riots then straight in final pots. I've not had to feed until week 3, either Biobizz Grow or Fishmix at half strength and plants have been fine. 

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Been using plant magic supreme for the last few plants , good results. 

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Recently got my hands on some fishmix, looks like good stuff!

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10 minutes ago, Lubdub said:

Recently got my hands on some fishmix, looks like good stuff!

It fucking stinks be careful not spill any, I once shook the bottle to give it a mix without the lid on properly and got it everywhere, couldn't get rid of the smell for days. 

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