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Development and Harvest Yields of Greenhouse Tomatoes in Six Orgnaic Growing Systems

VerdantGreen

VerdantGreen

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yeah thats the idea - i figured the pine bark and clay would be big particles and 70% of the mix.
im going to try it un-screened first, this is the (UK Product) Melcourt 'propagating bark' and it's the only one that the grain size starts at 2mm rather than 0 - so i figure it's been screened already. it may be better to screen some of the bigger particles out which i can always try if this doesnt work as is.

it'll have to be good to live up to what im using already. i may need to do a side by side i guess.
 
Dave Coulier

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VerdantGreen, I used to be a big proponent of Pine Bark like Spurr, but Ive moved on from it at this point.

Its a huge PITA to screen. It takes forever. It has poor Gas Diffusion when particle sizes are over 2mm, and even at 2mm its borderline.

The more research Ive done on pine bark the less enamored I am with it. Available Water, and Buffer Water are too low for my liking.

If that were my mix, I would increase SPM, and reduce the Pine Bark.

I do hope you'll have good results with it though.
 
mad librettist

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I screened out both the fines and the big pieces. Agreed, it was a PITA, and believe me it gets worse if you rent an apartment and have to do it in the one bathroom.

So far results are good, FWIW.

what is SPM?

Dave - could you help out maybe with measuring the effects of a living mulch on media properties?
 
Dave Coulier

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mad librettist said:
I screened out both the fines and the big pieces. Agreed, it was a PITA, and believe me it gets worse if you rent an apartment and have to do it in the one bathroom.

So far results are good, FWIW.

what is SPM?

Dave - could you help out maybe with measuring the effects of a living mulch on media properties?
Click to expand...

Could you elaborate on this?

SPM is Sphagnum Peat Moss. It too is a PITA to screen as well :)
 
mad librettist

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well, a while back when i was researching some of the info on this thread, I kept coming back to AL on gardenweb. He made a comment about how once the medium is fully colonized by roots, the roots themselves provide structure.

That's partially what led me to experiment with plants that could possibly get in there, give the soil some structure and a hundred little wicks, and give the other benefits of ground cover. So far the results from using micro-clover established before transplant are very encouraging, and I feel this opens up some possibilities for working with media thus far labelled "not ideal".
 
Microbeman

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I personally always liked the higher grade finer SPM product from Premier....Is it called Pro Moss?. It is darker in color, high content of microbes and does not require screening. After 2 years you cannot tell it from topsoil in a biologically active situation. Is it available south of the 49th?....dunno
 
VerdantGreen

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Dave Coulier said:
VerdantGreen, I used to be a big proponent of Pine Bark like Spurr, but Ive moved on from it at this point.

Its a huge PITA to screen. It takes forever. It has poor Gas Diffusion when particle sizes are over 2mm, and even at 2mm its borderline.

The more research Ive done on pine bark the less enamored I am with it. Available Water, and Buffer Water are too low for my liking.

If that were my mix, I would increase SPM, and reduce the Pine Bark.

I do hope you'll have good results with it though.
Click to expand...

thanks dave - yeah tbh the reason why i havent tried this mix yet was because i'm not really prepared to do loads of screening, and was dubious about the water holding capabilities.

could you elaborate on why the gas diffusion is poor? my logic would presume that it got better as the particles got bigger...
hopefully the airpots might help that - unless ive totally got the wrong end of the stick as to what gas diffusion is..

managed to get some biochar so im thinking 10% of that and reduce the pine bark to 40%

really i would like to reduce the peat to 0% - although i acknowledge that its a good ingredient.

VG
 
Dave Coulier

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VerdantGreen said:
thanks dave - yeah tbh the reason why i havent tried this mix yet was because i'm not really prepared to do loads of screening, and was dubious about the water holding capabilities.

could you elaborate on why the gas diffusion is poor? my logic would presume that it got better as the particles got bigger...
hopefully the airpots might help that - unless ive totally got the wrong end of the stick as to what gas diffusion is..

managed to get some biochar so im thinking 10% of that and reduce the pine bark to 40%

really i would like to reduce the peat to 0% - although i acknowledge that its a good ingredient.

VG
Click to expand...

Heres something that will help you answer your questions.

If I remember Spurrs explanation of Pore Tortuosity, as the particle sizes increase, gases in the rootzone have a longer path to travel to escape. Imagine being in a 'maze' with a bunch of long walls. Its gonna take awhile to find your way out. Now imagine if all the walls were 2-3 feet long instead. It'd be pretty easy to find your way out now.

So as the particle size increases, and pore tortuosity increases, gas diffusion is going to become limited due to the longer time it takes for gases to escape.

Read that study closely. You'll notice at even the 1-2mm pine bark size, the Gas Diffusion value is already at a level thats been suggested to be limiting to plant growth.
 
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