Is it going to be ok if i let this soil mix sit for only 2 weeks?

[weedlover_89]

Hello, i recently made a batch of soil mix with the following:

30% sphagnum peat moss
15% coco (for aeration)
15% clay pebbles and pumice (for aeration)
30% good quality humus

1 cup kelp meal per cubic foot of soil
0,5 cup neem meal per cubic foot of soil
0,5 cup of bat guano per cubic foot of soil
0,5 cup of organic fertilizer for tomatoes per cubic foot of soil

1 cup dolomite lime per cubic foot
4 cups of zeolite per cubic foot


This is my soil mix. Its intended for plants that will go into flowering. These plants have been already vegging for 35 days. What do you think? Don't want to burn them like i did with my first batch of soil.

 

[xmobotx]

what's it smell like?

give it a little test ~maybe see if some vegetable or cover crop seeds will start in it?

 

[EclipseFour20]

IMHO, if your goal is to allow the soil to adjust to the target pH (why you added dolomite), then 7-10 days after moistening the grow medium should be more than adequate.

Me, I wait about a week before using mine...which is what it takes for my soil pH to increase to the target number of 6.8. Testing the soil pH is how what I did...and after 7 days, my custom grow medium's pH stopped increasing (translation...achieved target pH--so why wait any longer?).

As to the fertility breakdown (kelp, bat guano and organic fertilizer)--kelp meal has a very long breakdown period. At 28 days only 14% of the kelp has been converted/broken-down but consumed nitrogen by delivering -6% (negative 6%). Compared to "organic fertilizer" like fish/feather/alfalfa meal--at 28 days about 59% has been converted/broken-down and delivered 58% of it's available nitrogen; at 7 days, only 8% kelp is converted/broken-down--compared to "organic fertilizer" at 43%. Big difference between the two--35 basis points!

So....if you are "cooking" it, then it probably depends on what your "goal is"...but if increasing the soil's pH is your goal, a simple soil pH test kit is one way to verify if "it's ready...or not" after a week or so.

Source for organic breakdown times--smallfarms.oregonstate.edu/sites/default/files/Sullivan_et_al_2010_World_Congress_Soil_Science.pdf

 

[weedlover_89]

what's it smell like?

give it a little test ~maybe see if some vegetable or cover crop seeds will start in it?

Hey, it has an earthly smell! But for sure i would not use it in newly planted seeds! I had made a similar batch of soil some time ago which was used to transplant seeds that had been living for about 1 week. It burned them and stunted their growth. Took a while to get back on track. Now they are flying but back then they were burned. I had overdone it a bit with bat guano though....

IMHO, if your goal is to allow the soil to adjust to the target pH (why you added dolomite), then 7-10 days after moistening the grow medium should be more than adequate.

Me, I wait about a week before using mine...which is what it takes for my soil pH to increase to the target number of 6.8. Testing the soil pH is how what I did...and after 7 days, my custom grow medium's pH stopped increasing (translation...achieved target pH--so why wait any longer?).

As to the fertility breakdown (kelp, bat guano and organic fertilizer)--kelp meal has a very long breakdown period. At 28 days only 14% of the kelp has been converted/broken-down but consumed nitrogen by delivering -6% (negative 6%). Compared to "organic fertilizer" like fish/feather/alfalfa meal--at 28 days about 59% has been converted/broken-down and delivered 58% of it's available nitrogen; at 7 days, only 8% kelp is converted/broken-down--compared to "organic fertilizer" at 43%. Big difference between the two--35 basis points!

So....if you are "cooking" it, then it probably depends on what your "goal is"...but if increasing the soil's pH is your goal, a simple soil pH test kit is one way to verify if "it's ready...or not" after a week or so.

Source for organic breakdown times--smallfarms.oregonstate.edu/sites/default/files/Sullivan_et_al_2010_World_Congress_Soil_Science.pdf

Hey, awesome info! I have still not added the full amount of dolomite lime required for the soil mix...I am short of about 2 cups of dolomite lime. Actually i have ordered some calcite (similar properties with dolomite lime,), waiting for it to come in the next couple days.

My goal is to bring the PH to the desirable levels and NOT burn my plants. I guess that because they have been vegging for a while and because i was more careful with the quantities of amendments i mixed, i won't have to wait a full month. It would be bad to stunt them before they go into flowering mode.

 

[EclipseFour20]

If you read that paper I linked, it concluded that after 70 days, most organic fertility will be 60-100% consumed/broken-down. So if one were to add the time for vegging and flowering, you will need more than 70 days of fertility to get all the way to harvest.

So...around 60 days after transplanting is a good time to replenish some of that consumed fertility--I use top dressings (dry fertility), bat guano teas, water soluble and foliar sprays to bridge the fertility gap.

As a rule, the finer the organic fertilizer is, the faster it will breakdown. I grind all my dry fertility in an old coffee grinder, then mix it to the soil at time of transplant--not before.

 

[trichrider]

great link! may I include it in my list?

http://smallfarms.oregonstate.edu/s...an_et_al_2010_World_Congress_Soil_Science.pdf

also, regarding 'cooking' soil, some humic/fulvic acid would accelerate that process.

 

[Mikell]

great link! may I include it in my list?

http://smallfarms.oregonstate.edu/s...an_et_al_2010_World_Congress_Soil_Science.pdf

I second that

 

[ct guy2]

I would add more aeration in the mix prior to planting. How does it drain? Personally I like to see aeration amendments around 30% of my total media and I wouldn't consider coco as "aeration."

That doesn't look like a very hot mix to me based on ingredients and ratios. You should be fine to plant in it.

 

[EclipseFour20]

Yep, air & water porosity...ideally, you want about 10% (by volume) or more air space in container growing medium; oxygen is free and if the roots have less than 10%, no bueno.

As to water porosity, the ideal grow medium should hold about 50% water (by volume) with available water about 30%. Selection of the right variety and quantity of aggregates is how you accomplish this. Perlite holds water but does not retain water (like bark), perlite creates air spaces when it releases the held water; whereas certain aggregates like bark, calcined clay, pumice, etc, will hold then release water but create zero "air space". So it may not be as simple as "adding more perlite", rather it could be "add a bit of this and a bit of that".

This pamphlet explains how to determine your porosity #s...it is not that hard. http://njaes.rutgers.edu/pubs/publication.asp?pid=fs881

 

[weedlover_89]

Hey eclipse, once again, very interesting link posted! I am going to check it out thoroughly! You say "its not as simple as adding more perlite".

According to ct guy 2(thanks for posting here buddy), coco is not considered aeration amendment and i had added about 5 gallons to 30 gallons of soil mix (i.e ~ 15% of my soil mix is coco). So, i am missing about 15% aeration amendments. Would it be ok adding for example 5% perlite, 5% clay or vermiculite, 5% pumice to compensate for the 15 % missing in my aeration amendments?

And what about sphagnum peat moss, add a little more or leave it as is?

@ ct guy 2: I have the soil mix sitting in two rubbermaid containers, no drainage holes, it seems to absorb water quite well.
I got a bit confused now

 

[EclipseFour20]

Best answer...for the long run is to experiment with various aggregates and different ratios and see what you get. Then begin to tweak it (lil bit more of this....lot less of that, etc).

My grow mix includes promix (peat), bark, compost, ewc, perlite, vermiculite, calcined clay and a goodly amount of food grade diatomaceous earth (Fossil Shell Flour). Everything holds water...some more than others, some less than others, as a result, the medium has high CEC and dialed in porosity levels.

Pumice is something I used to add, but no more--IMHO, it does nothing. Porous? Yes, but the water gets locked up inside the pumice pockets and never becomes available to the soil/plant do to minimal "surface tension" (small hole with a big cavity filled with water....its gonna take a lot of sucking to get that water out...lol).

BTW, I use equal amounts of perlite, vermiculite, promix and bark (18% each) in my mix and I keep calcined clay around 6-7%.

 

[lostenspace]

Hello e420,

Thanks for the explanation, this helped me. What type of bark do you use in your mix and what grade?

Thanks,

 

[weedlover_89]

Best answer...for the long run is to experiment with various aggregates and different ratios and see what you get. Then begin to tweak it (lil bit more of this....lot less of that, etc).

My grow mix includes promix (peat), bark, compost, ewc, perlite, vermiculite, calcined clay and a goodly amount of food grade diatomaceous earth (Fossil Shell Flour). Everything holds water...some more than others, some less than others, as a result, the medium has high CEC and dialed in porosity levels.

Pumice is something I used to add, but no more--IMHO, it does nothing. Porous? Yes, but the water gets locked up inside the pumice pockets and never becomes available to the soil/plant do to minimal "surface tension" (small hole with a big cavity filled with water....its gonna take a lot of sucking to get that water out...lol).

BTW, I use equal amounts of perlite, vermiculite, promix and bark (18% each) in my mix and I keep calcined clay around 6-7%.

Thank you for your answer buddy, you are very helpful and seem very knowledgeable on the subject! Pumice is out of the question it seems. I will proceed with vermiculite and perlite. But how much?

15% of my total soil mix to substitute for aeration i thought i would have with coco? And no more peat? Since i will be adding about 25 liters of aeration amendments, won't i have to add more kelp meal, more neem meal, a little bit more humus etc etc? This is where i am getting confused.

Consider the 15% coco/15% peat to be my base soil and proceed to add only perlite,vermiculite?

 

[ct guy2]

Hey eclipse, once again, very interesting link posted! I am going to check it out thoroughly! You say "its not as simple as adding more perlite".

According to ct guy 2(thanks for posting here buddy), coco is not considered aeration amendment and i had added about 5 gallons to 30 gallons of soil mix (i.e ~ 15% of my soil mix is coco). So, i am missing about 15% aeration amendments. Would it be ok adding for example 5% perlite, 5% clay or vermiculite, 5% pumice to compensate for the 15 % missing in my aeration amendments?

And what about sphagnum peat moss, add a little more or leave it as is?

@ ct guy 2: I have the soil mix sitting in two rubbermaid containers, no drainage holes, it seems to absorb water quite well.
I got a bit confused now

First off, get it out of those containers or drill some holes to allow the soil to breathe. I prefer smart pots or even just a pile on the floor on a tarp. What I'm asking is if you put the soil in a small container with holes on the bottom, does the water drain down to the bottom or pool on the top of the soil and take a long time to work it's way to the holes on the bottom?

I've had great success with pumice for many years. I use a combination of medium and large pumice (about 2/3 medium) when making soils. Adding those aeration amendments in those quantities would be fine in my opinion. Keep in mind that you don't want "fine" but rather larger size particulate in the aeration. Vermiculite is unique from the other two in that it will also increase your CEC.

 

[ct guy2]

Thank you for your answer buddy, you are very helpful and seem very knowledgeable on the subject! Pumice is out of the question it seems. I will proceed with vermiculite and perlite. But how much?

15% of my total soil mix to substitute for aeration i thought i would have with coco? And no more peat? Since i will be adding about 25 liters of aeration amendments, won't i have to add more kelp meal, more neem meal, a little bit more humus etc etc? This is where i am getting confused.

Consider the 15% coco/15% peat to be my base soil and proceed to add only perlite,vermiculite?

I would get up to that 30% I suggested and then amend the soil with your ingredients at a rate commensurate to your total amount of media. That means you will need to add more of the kelp, neem, etc...

Personally I prefer peat over coco for a variety of reasons. Higher CEC, existing microbiology, no need to add sulfur, more consistency in quality across brands, etc...

But since you already are using coco, that's fine. Were you adding sulfur or gypsum to your mix, I forgot to check.

 

[EclipseFour20]

Think backwards...build your aggregates based on what you want. My ratio works for me but may not work for you--so that is not important. Rather what is important is your aggregate selection and it's final mixture.

I wanted high CEC, so I include calcined clay, peat, compost, vermiculite in goodly numbers. I wanted the aggregates to hold lots of water at various amounts, so I include bark, perlite and vermiculite.

Now...why 15% coco/15% peat? What is the objective? IMHO, both of those mediums are basically "interchangeable" so really you have 30% of the "same thing".

Here is a link to a great grow medium resource (even if it was published by a UN agency)...lol. www.fao.org/hortivar/scis/doc/publ/8.pdf

Around page 40 is where the substrate analysis starts if you want to skip the techy stuff. Most enlightening as they discuss all the usual suspects...including Pumice (page 74):

Rather straight forward, I say.

 

[EclipseFour20]

CT, check out ATTRA's publication titled, "Potting Mixes for Certified Organic Production"...available here: https://attra.ncat.org/attra-pub/summaries/summary.php?pub=47

It has a wealth of information plus about 5 pages of proven grow medium recipes. Here's a teaser--

"MAKING YOUR OWN

All good potting media should meet the needs of
plant roots for air, water, nutrients, and support.
These needs will vary, however, depending on
the plant and its stage of growth. The technical
details are beyond the scope of this publication
and can be found in standard horticultural
literature and publications distributed by the
Cooperative Extension Service. A list of several
information resources about growing media is
in Appendix 2. Some of these focus on organic
systems; others address conventional production
but contain basic and/or relevant information.
Anyone who wants to produce consistent, highquality
growing media should study and do
detailed research.

Working from tried-and-true recipes is a good
idea, especially at the beginning. Appendix 3
features several recipes for organic media blends.
Some of these recipes are found in published
literature; others are from conference and workshop
handouts or notes with uncertain authorship.
Experimentation is the only sure way of
knowing which blend or blends will work best
for a particular farm or crop."

Enjoy!

 

[EclipseFour20]

Hello e420,

Thanks for the explanation, this helped me. What type of bark do you use in your mix and what grade?

Thanks,

Sorry for the late answer...missed your post.

I found "orchid bark" to be the best...finest grade--not chunks. Pine bark may require additional Nitrogen to breakdown as it seldom is fully decomposed. I pay about $9 for 2 cuft of orchid bark, rather affordable.

 

[ct guy2]

Think backwards...build your aggregates based on what you want. My ratio works for me but may not work for you--so that is not important. Rather what is important is your aggregate selection and it's final mixture.

I wanted high CEC, so I include calcined clay, peat, compost, vermiculite in goodly numbers. I wanted the aggregates to hold lots of water at various amounts, so I include bark, perlite and vermiculite.

Now...why 15% coco/15% peat? What is the objective? IMHO, both of those mediums are basically "interchangeable" so really you have 30% of the "same thing".

Here is a link to a great grow medium resource (even if it was published by a UN agency)...lol. www.fao.org/hortivar/scis/doc/publ/8.pdf

Around page 40 is where the substrate analysis starts if you want to skip the techy stuff. Most enlightening as they discuss all the usual suspects...including Pumice (page 74):

View Image
View Image
View Image

Rather straight forward, I say.

Yeah I'm not using pumice to pick up more EC, and vermiculite is too expensive on a commercial scale. Perlite floats in the soil, making it hard to keep the soil evenly mixed over time. I find I get enough water holding capacity from the peat and compost, in fact, I have had to up my amount of pumice to around 34% to allow for proper drainage in my current mix.

 

[ct guy2]

CT, check out ATTRA's publication titled, "Potting Mixes for Certified Organic Production"...available here: https://attra.ncat.org/attra-pub/summaries/summary.php?pub=47

It has a wealth of information plus about 5 pages of proven grow medium recipes. Here's a teaser--

"MAKING YOUR OWN

All good potting media should meet the needs of
plant roots for air, water, nutrients, and support.
These needs will vary, however, depending on
the plant and its stage of growth. The technical
details are beyond the scope of this publication
and can be found in standard horticultural
literature and publications distributed by the
Cooperative Extension Service. A list of several
information resources about growing media is
in Appendix 2. Some of these focus on organic
systems; others address conventional production
but contain basic and/or relevant information.
Anyone who wants to produce consistent, highquality
growing media should study and do
detailed research.

Working from tried-and-true recipes is a good
idea, especially at the beginning. Appendix 3
features several recipes for organic media blends.
Some of these recipes are found in published
literature; others are from conference and workshop
handouts or notes with uncertain authorship.
Experimentation is the only sure way of
knowing which blend or blends will work best
for a particular farm or crop."

Enjoy!

Good article, though I would say those recipes really jump all over the board. The ratios are quite dramatically different between them.