-
ICMag with help from Landrace Warden and The Vault is running a NEW contest in November! You can check it here. Prizes are seeds & forum premium access. Come join in!
Soil Analyzed - what now?
- Thread starter Papulz
- Start date
for readin.
i believe it was a result of my sampling technique, i should have thoroughly mixed the pots before core sampling.. I had top dressed with a cup or so of 0 0 7 guano back in august.
im tryin to wrap my mind around the boron, chloride and sulfate situation.
these folk did my testing.
http://www.fglinc.com/frmAnalyses.php?choice=Soil+Analyses&division=Ag
im tryin to wrap my mind around the boron, chloride and sulfate situation.
these folk did my testing.
http://www.fglinc.com/frmAnalyses.php?choice=Soil+Analyses&division=Ag
Last edited:
so ive got my recommendation from the lab back, they rec using a potassium fert as well as adding sulfur to the soil.
I intend to do both, as well as add a significant amount of N ferts in the form of blood meal and alfalfa meal.
anyone know how to get some chloride back in there? afoaf recommended cow manure.
Ive already started w an application of sulfur to the soil, but am curious about what other tweaks the mix needs. thanks for reading!
I intend to do both, as well as add a significant amount of N ferts in the form of blood meal and alfalfa meal.
anyone know how to get some chloride back in there? afoaf recommended cow manure.
Ive already started w an application of sulfur to the soil, but am curious about what other tweaks the mix needs. thanks for reading!
Sinkyone
Member
Did they say what your % of organic matter is? That is an important one for cannabis. You definitely need a LOT more N in there, as well as K (obviously). I personally have only had issues with too much chloride, not too little so I can't help you on that one. Saturation seems high but probably nothing to worry about. I am a little perplexed that that is so high yet the moisture is so low. Boron levels are nothing to worry about IMO. I would go with what the labs recommends, they know their stuff.
Good to see more people testing their soil. The more this sort of info gets out there the more likely it is that the ideal levels for cannabis will be discovered.
Good to see more people testing their soil. The more this sort of info gets out there the more likely it is that the ideal levels for cannabis will be discovered.
Sinkyone
Member
On these test organic matter refers to soluble organic matter (SOM) which is the humic content of the soil. The term 'organic matter' is almost always used incorrectly on these forums. Adding 20% worm castings does not mean you added 20% SOM as it is not pure SOM, nor is any form of compost. People tend to refer to any sort of compost or manure or castings as 'organic matter' and this is not correct.
You should probably have the lab double check my math since math is not my strong point but here is what I came up with. Assuming you are using 13-0-0 blood meal you will need 7.7 lbs of blood meal to add 1lb of pure elemental N to 1,000 square feet (100 / 13 = 7.7). This is our baseline as that is the units the test uses.
Breaking that down smaller, 20 cubic feet is 2% of 1,000 square feet. If you use 4 lbs of bloodmeal that will add 0.52 lbs of pure elemental N to 20 cubic feet (4 x 0.13 = 0.52). Yes I realize I am using the two interchangeably, for these purposes it is fine. So since 20 feet is 2% of 1,000 feet that means we need to multiply by a factor of 50 to get back to the numbers the tests uses. So (50 x .052 = 26). Adding that much blood meal should get your N number to '26' on the test. Like I said have the lab double check my math skills are not the best but I am pretty sure I calculated those correctly. I always have the lab double check my math when I do my tests just in case. Using this formula you should be able to figure out how much the 1 lb of alfalfa meal will add.
That is a good start but I would add in some slow release N, like in the form of feather meal as well. You need to be careful dealing with fast release N like blood meal and alfalfa they can burn plants. I like to use mostly slow release N on my initial soil prep and then follow up with top dressings of the faster release N like guano to make sure I don't burn the plants when they first go in.
You should probably have the lab double check my math since math is not my strong point but here is what I came up with. Assuming you are using 13-0-0 blood meal you will need 7.7 lbs of blood meal to add 1lb of pure elemental N to 1,000 square feet (100 / 13 = 7.7). This is our baseline as that is the units the test uses.
Breaking that down smaller, 20 cubic feet is 2% of 1,000 square feet. If you use 4 lbs of bloodmeal that will add 0.52 lbs of pure elemental N to 20 cubic feet (4 x 0.13 = 0.52). Yes I realize I am using the two interchangeably, for these purposes it is fine. So since 20 feet is 2% of 1,000 feet that means we need to multiply by a factor of 50 to get back to the numbers the tests uses. So (50 x .052 = 26). Adding that much blood meal should get your N number to '26' on the test. Like I said have the lab double check my math skills are not the best but I am pretty sure I calculated those correctly. I always have the lab double check my math when I do my tests just in case. Using this formula you should be able to figure out how much the 1 lb of alfalfa meal will add.
That is a good start but I would add in some slow release N, like in the form of feather meal as well. You need to be careful dealing with fast release N like blood meal and alfalfa they can burn plants. I like to use mostly slow release N on my initial soil prep and then follow up with top dressings of the faster release N like guano to make sure I don't burn the plants when they first go in.
much obliged for breakin it down sinky, that math helps a lot.
In talking with the ag director for the lab - he thought an application of sulfur might not be warranted and is confused as I am about the PH.
my plan is to hit it with feather/alfalfa/sulfate of potash
think i should greensand and kelp at the same time?
I keep readin and hearing about that 6.5 to 1 cal mag thing..
Contemplating adding oyster shell flour to help that, but afraid of ph!
also contemplating composted manure additions..
thoughts? thanks everybody!
In talking with the ag director for the lab - he thought an application of sulfur might not be warranted and is confused as I am about the PH.
my plan is to hit it with feather/alfalfa/sulfate of potash
think i should greensand and kelp at the same time?
I keep readin and hearing about that 6.5 to 1 cal mag thing..
Contemplating adding oyster shell flour to help that, but afraid of ph!
also contemplating composted manure additions..
thoughts? thanks everybody!
Chr0nicles
Member
Check out the book "The Intelligent Gardener" by Steve Solomon. I found it amazingly helpful for understanding all this stuff...
Y
YosemiteSam
Get some gypsum in there and use some runoff to get rid of some of the Mg. Your soil will be tight otherwise. Gypsum will give you the sulfate you need. With your high cec you really want Ca base cation saturation to be around 70%...this should be your number 1 goal.
If you don't care about being organic ammonium sulfate as the N source would help get your pH back in line...you really want your base cation saturation of H to be 12%
Use K2SO4 to get base cation saturation of K up to 5% or so.
At least in my opinion, take it for what it is worth
If you don't care about being organic ammonium sulfate as the N source would help get your pH back in line...you really want your base cation saturation of H to be 12%
Use K2SO4 to get base cation saturation of K up to 5% or so.
At least in my opinion, take it for what it is worth
Y
YosemiteSam
1 lb of gyspum is good. Gypsum will work cause you are already at 63% base cation saturation of Ca...you want the sulfate to help you lower Mg.
You need around 1 pound of N per yard of soil (based on your specific cec...does not apply to any other soil), provided the soil is living. So...just to make it simple for me...lets say you wanted to use feather meal at 13-0-0. That means 13% N...so lets say you want to add .8lbs since you have some in the mix already....0.8 divided by .13 (13%) is 6 lbs of feather meal.
You would have to work that out depending on the exact sources of N you want to use
Lets just do it...if your alfalfa is say 3% N then a pound will provide 0,03 lbs of N. So you need more feather meal than you planned...or add another source of N and split it up.
You are fixin to overdo K ...again in my opinion.
For K...I forget how much is in your mix now. But you only need about 0.5 lbs in a yard of soil, again with your cec.
For starters I would not use that much kelp...yes it is good, but some of those hormones, auxins, etc delay the plant finishing if you go too high. I would limit it to 0.5 lbs per yard of dirt.
And even if you want to get an entire 1/2 lb from K2SO4 you are only looking at 1 lb per yard cause it is 50% K
Others will have different opinions...this is just mine.
edit...be aware I keep talking in yards cause that is what is simple for me...20 cubic ft you would need to multiply yard numbers by 20/27 = 0.74
You need around 1 pound of N per yard of soil (based on your specific cec...does not apply to any other soil), provided the soil is living. So...just to make it simple for me...lets say you wanted to use feather meal at 13-0-0. That means 13% N...so lets say you want to add .8lbs since you have some in the mix already....0.8 divided by .13 (13%) is 6 lbs of feather meal.
You would have to work that out depending on the exact sources of N you want to use
Lets just do it...if your alfalfa is say 3% N then a pound will provide 0,03 lbs of N. So you need more feather meal than you planned...or add another source of N and split it up.
You are fixin to overdo K ...again in my opinion.
For K...I forget how much is in your mix now. But you only need about 0.5 lbs in a yard of soil, again with your cec.
For starters I would not use that much kelp...yes it is good, but some of those hormones, auxins, etc delay the plant finishing if you go too high. I would limit it to 0.5 lbs per yard of dirt.
And even if you want to get an entire 1/2 lb from K2SO4 you are only looking at 1 lb per yard cause it is 50% K
Others will have different opinions...this is just mine.
edit...be aware I keep talking in yards cause that is what is simple for me...20 cubic ft you would need to multiply yard numbers by 20/27 = 0.74
Last edited:
was highly contemplating about 4 pounds of oyster flour in each as well for that reason, just was searching for something that wouldnt change ph if possible. was guessing 4 each for an addition of approx 180 lb per 1000sqf
as i begin to figure it.. ive currently got .3456 pure elemental N from the feather meal in each sack 2.7 lb..
then .036 from the kelp meal 3.6 lb (cant unmix it!)
.024 from alfalfa 1 lb
so thats .4056 in pure N per pot by my math. youd recommend getting another .6 of pure N in there?
the K2SO4 i got is not solution grade... took me forever to source it round town. the lab recommended 23.6 of K in my case.. yet rendered no N rec. it was weird man.
as i begin to figure it.. ive currently got .3456 pure elemental N from the feather meal in each sack 2.7 lb..
then .036 from the kelp meal 3.6 lb (cant unmix it!)
.024 from alfalfa 1 lb
so thats .4056 in pure N per pot by my math. youd recommend getting another .6 of pure N in there?
the K2SO4 i got is not solution grade... took me forever to source it round town. the lab recommended 23.6 of K in my case.. yet rendered no N rec. it was weird man.
Last edited:
Y
YosemiteSam
Oyster shell is 96% CaCO3. It will drive your pH higher, not lower.
Gypsum will allow Mg to get out of the mix...when you replace Mg on the base sites with Ca it actually lowers the pH. A molecule of Mg buffers 1.4 x more than Ca.
And when you use gypsum Ca will replace Mg on the base sites...proven over and over in agriculture.
1 lb is plenty to start. While Ca is extremely important too much will fuck you proper...it can virtually block all cations. You do not want to be much over 70% base cation saturation of Ca.
edit....http://www.acresusa.com/toolbox/reprints/Feb07_CationAnionConnection.pdf
edit dos.....http://www.acresusa.com/toolbox/reprints/ExcessiveLime_kinsey_June01.pdf
Gypsum will allow Mg to get out of the mix...when you replace Mg on the base sites with Ca it actually lowers the pH. A molecule of Mg buffers 1.4 x more than Ca.
And when you use gypsum Ca will replace Mg on the base sites...proven over and over in agriculture.
1 lb is plenty to start. While Ca is extremely important too much will fuck you proper...it can virtually block all cations. You do not want to be much over 70% base cation saturation of Ca.
edit....http://www.acresusa.com/toolbox/reprints/Feb07_CationAnionConnection.pdf
edit dos.....http://www.acresusa.com/toolbox/reprints/ExcessiveLime_kinsey_June01.pdf
Y
YosemiteSam
I would at least get another 0.1 lbs in there...that will work fine for the plant. And I would use a different source...diversity and what not.
But the thing is you have a cec of 50 something...pretty high. Your soil can hold twice the nutes of your normal mid 20s cec soil. You don't have to completely load it...but you can. If you are planning to re use it that means less amendment next time. It also means more N available for the microbes...so they can recycle nutrients mo better.
check this out yosemite, some of my plants get this every year. this pic is from last year midway throu flower
definitely seeing the error of my ways blinding amending! thanks so much for taking the time.
seriously man.
blood + feather?
ive used and enjoyed both.. what do you like for N
afoaf likes corn gluten.. midwesterner he is.
definitely resisting the urge to lime... as everything ive read tells me that with a mix thats 80% peat moss i need to lime or adjustment every year.
Probably need to understand other buffering agents better before jus throwing it in the pot eh.
still learning so much
definitely seeing the error of my ways blinding amending! thanks so much for taking the time.
seriously man.
blood + feather?
ive used and enjoyed both.. what do you like for N
afoaf likes corn gluten.. midwesterner he is.
definitely resisting the urge to lime... as everything ive read tells me that with a mix thats 80% peat moss i need to lime or adjustment every year.
Probably need to understand other buffering agents better before jus throwing it in the pot eh.
still learning so much
Last edited:
