Phosphorus Availabilty

[SecretGardener]

So I have read Teaming With Microbes and varoius other sources on the net (as well as here) and I still have a question about phosphorus availability in soils. In Teaming With Microbes the author states how even water soluble P is only available to roots for a few seconds before it either runs through the soil or gets bound up.

It seems the only way plants get a consistent form of P is if they have a symbiotic relationship with mycorrhizae. Also, beneficial fungi break it down and 'deliver' it to the rhizosphre correct?

So, if you have trouble getting significant fungi numbers in your AACTs and do not have mycorrhizae/root symbiosys then you're going to need to add a soluble p source to your teas (like indonesian guano etc..) during flowering, right?

I ask because I have two plants 5 weeks flowering currently. One that has been infected with myco's and one that has not (except for what they claim is in ProMix HP). The one without is starting to show what I believe is a P deficiency. I thought maybe it has depleted all the P but its Dutch Passion Strawberry Cough strain and from what I have read about the strain it is a light feeder. Plus both plants were put in brand new LC's mix #2 amended with blood/bone/kelp so it can't be depleted lol.

The other plants (serious seeds AK-47) roots were covered with Espoma BioTone before transplanting into flowering mix and it is doing great! The individual buds when compared to the strawberry cough are fuller and it shows NO signs of a single deficiency!

I'm not concerned with the deficiency because the buds still look nice and it will still yield decent but its more that I want to understand what is going on...and if I can fix it I will.

I will post some pictures when I get home just to verify P deficiency. I know there is a plant infirmary but everyone there gives chem/hydro advice for the most part.

Thanks in advance for you help

 

[Phedrosbenny]

You said it looked to you like it had a P definciency...can you descibe what it looks like to you?

 

[SecretGardener]

You said it looked to you like it had a P definciency...can you descibe what it looks like to you?

I'll post pictures in a little, but for now I'll try to describe it.

I noticed the deficiency on the oldest lowest fan leaves first. The leaves yellow and then start to wilt. The veins are still green though. Over a week or so the leaves slowly shrivel up and then fall off - I did not notice any necrotic black spots that are common with P deficiencies though... Once the oldest lowest leaves died the rest of the fan leaves on the plant started to slowly turn yellow and I know soon they'll die too. The leaf death works its way up the plant as if the plant is systematically draining itself. I guess it could be an N deficiency but would this show in week 4 of flower or later? And would the leaves die and fall off from an N deficiency or just yellow?

I'm horrible at spotting deficiencies because they all look the same to me, I only assumed P because of the circumstances I wrote about in my OP.

 

[TickleMyBalls]

what you have does not sound like a P deficiency to me. a P deficiency will turn your leaves black, but they go through purple to get there. certain strains the nugs will be stunted and turn purple with a P deficiency.

as far as P availability... this is true of most phostphate derived nutrients, the trick is to use phosphites. they are more soluble and readily available to the roots. check out this thread...

http://www.icmag.com/ic/showthread.php?t=171808

 

[Microbeman]

Are you sure it is not just the natural end of life for the plant as it 'ripens' the flowers. (5 weeks you said, right?)

 

[SecretGardener]

Are you sure it is not just the natural end of life for the plant as it 'ripens' the flowers. (5 weeks you said, right?)

Yes it will be 5 weeks flowering this sunday (9/12/10). The problem started to creep up at around 4 weeks. But, you're right it may well be normal at 5 weeks for this strain as it is the first time I've grown it.

Here are some pictures. First picture is of the AK-47, you can see leaves are happy. The rest are the strawberry cough plant in question.

The closer I look I'm seeing signs of a few deficiencies, so it may well just be the natural end of the plants life cycle.

 

[VerdantGreen]

sounds more like N def to me if its going for the oldest leaves first.

it also happens naturally during mid-late flowering.

 

[Phedrosbenny]

It looks like its just the plant using up its Nitrogen reserves.

 

[SecretGardener]

what you have does not sound like a P deficiency to me. a P deficiency will turn your leaves black, but they go through purple to get there. certain strains the nugs will be stunted and turn purple with a P deficiency.

Yeah no black leaves yet, some maroon/dark red on the leaf margins if you look closely, could be going purple/black - guess time will tell.

sounds more like N def to me if its going for the oldest leaves first.

it also happens naturally during mid-late flowering.

It looks like its just the plant using up its Nitrogen reserves.

So seems like it is just a natural occurrence, appreciate the input guys! Thanks for helpin' a newb out

 

[staff11]

Picture 3 looks almost like a P deficiency to me. I see the purple spots and stems. However pic 2 looks like a normal lower fan leaf later in flower. Keep an eye out for necrotic or dead areas on the leaves on the plant in pic three for the next week or so.
And the leaves it is on that I see are not just the bottom, just monitor them. If you need a P source you could top dress with guano, which I have had to do plenty of times before.

 

[Microbeman]

sounds more like N def to me if its going for the oldest leaves first.

it also happens naturally during mid-late flowering.

Okay Mr. Green, which is it? Make up yer mind eh! <GRIN>

 

[VerdantGreen]

Okay Mr. Green, which is it? Make up yer mind eh! <GRIN>

a bit of both?

5 weeks into flower - around halfway through - is a little early for natural senescence fading imo. they could be a little rootbound - just need a couple of light feeds to slow down the fading for the next few weeks.

VG

 

[SecretGardener]

a bit of both?

5 weeks into flower - around halfway through - is a little early for natural senescence fading imo. they could be a little rootbound - just need a couple of light feeds to slow down the fading for the next few weeks.

VG

They are due for a watering today. I don't have an AACT ready so I was just going to mix up 1 Tbs. of high N guano and 2 Tbs. of high P guano into a gallon of de-chlorinated water and apply. Will that suffice?

 

[VerdantGreen]

that should work. you wont make the yellow leaves turn green again but it will slow down the fading. dont go too mad with feeding though as there isnt loads of time left for them to use it. a little liquid seaweed might be good if you have it. if the plants are rootbound then leave them standing in a saucer of runoff for a few hours as this helps them absorb food better.

VG

 

[SecretGardener]

Dudes lol. I took a little sample from the strawberry cough the other day when we were all inspecting its leaves....i kept looking at those nugs and just had to sample it even if its only at 5 weeks...

It's amazing, I wish I could share it with you all! It tastes like fruit and it creeps up on you. Super up high...Makes you want to walk around hugging random people lol.

But I am excited because this is my first organic grow and after tasting this stuff uncured and early it makes me want to throw out my chem grown herb !

 

[SOTF420]

Benie's are great they surely make a big difference, I even use them in Coir with hydro and it's like night and day. When your leaves are turning yellow and falling off at the end you know your plants are flushing out and you are going to have great clean smooth smoke. Let us know how it goes man!

 

[Albertine]

I've been thinking the scents I'm getting off of this first organic soil grow are amazingly fruity - maybe I'm not imagining it.
By the way your photos look to me like what I'm calling sulfur/mag deficiencies - interveinal yellowing, upside down canoeing, tops going light. Mag, mag, mag -
it's been mag all along, hard to keep up with them. It happens to me when they get pot bound.

 

[SecretGardener]

I've been thinking the scents I'm getting off of this first organic soil grow are amazingly fruity - maybe I'm not imagining it.
By the way your photos look to me like what I'm calling sulfur/mag deficiencies - interveinal yellowing, upside down canoeing, tops going light. Mag, mag, mag -
it's been mag all along, hard to keep up with them. It happens to me when they get pot bound.

Yes I do think they are pot bound, even in a 5 gallon bucket (well only really 3.5 gallons of soil in there). I've come to realize that the plant in question requires ALOT of root space. I'm pretty sure there are multiple deficiencies going (MG/P/N) on and I'm not gonna stress about it. Next time I'll give the roots more space. I'll post pictures when I harvest in a few weeks of the root ball to confirm our suspicions

Oh and yes, I thought *I* was imagining the fruity smell too but my wife walked in the room and said it smelled like hawaiin punch So you're probably not imagining it.

Why the hell you would not want to grow organic after these results is beyond me.