Can one of you guys talking about his issue being high Phosphorus explain what you mean? I can’t find any online references to high P yellowing bottom leaves nor in my books. I did find references to high P manifesting as deficiencies in zinc, calcium, magnesium, iron or copper, with zinc being the most common (Cervantes, 2006).
A zinc deficiency shows chlorosis of new and younger leaves, not old bottom leaves... so I’m puzzled where your information comes from.
Without anymore info, this is classic nitrogen deficiency. My guess is the plant is using it to fuel the stretch.
As for run-off pH being a new thing.. new to you I guess! It is useful to me as an indicator of what’s happening in the soil, and I can list references from sources if you’re curious about the topic. Soil slurry pH and soil probes are sketchy at best as they don’t really give you a good sample size. And it’s not a homogenous mixture.
Yeah screwed the pooch on N def expression but he's not got an N issue of it's starting bloom (increasing N now will not help much, too late)......I still watch my tops or upper plant for N def if I want to correct..(Guess I run too many N sensitive strains) ...Habit sometimes trumps my schooling. Still, low N is easy to see from real light green coloring, graduated in the whole plant.
As far as Cervantes goes. I gotta giggle a bit here, sorry.
Books can be nice tools. Yet he and others, limit what they say in books to what actual real world issues look like and are. How really old is that first publication? At that time, had he seen issues from nutrient charting that have come about by our time now? He's working on his experience from what he feeds.....At the time that book was written. He was well versed in Jack's classic and maybe a few others in the 3 part style of use. Also, bet you dimes to dollars he did not use the charting, for those "3 parts." He calculated the NPK values that
he wanted to apply to his plants!
Now then. In bloom when you get early yellowing of the leaves (starts with stem leaves) that progress up and then out branching.
This is a sure sign of using too much P. P acts like a ripening agent, when you use too much. It acts like one with out too much....
Many (far to many) nutrient makers drop N and increase P way to much! The high P is making the plant think it's closer to finish then it is...Others will still use far to much P but, elevate the N to "mask" the high P. This elevated N is not good either, and still the lower leaves yellow faster then they should! Organic growers believe that green to the end is better but, yes, we get natural color shifts near the end time.. That's the key here - near the end!
Still, it's easy to see a low N situation as it's being expressed in the whole plant as too light a color green in a variable way, bottom to top or top to bottom. NOT a
sudden yellow out of the lower leaves and quick progression up the plant.
It's not the lack of N but, the high P doing the work here. The real reason is poor nutrient feed charting and the makers jumping on the band wagon of "more is better" advertising and unneeded levels of P&K because they do this or that....
The makers of Dyna Grow defied the market trend and did not make stand alone grow and bloom products for some years (can you actually remember that far back?). Then, due to falling sales due to the other makers hype on how great the stand alone products - with their gee whizz boosters make your grow increase in (insert what ever stupid claim you know here). That they buckled and added a stand alone nutrient line....The CEO made a statement to that and wished they didn't have to make that leap.
FOLIAGE PRO does everything start to finish......So does a few Jack's products and they are STILL very popular.....Let me have you open that Jorge book again.. Now look at some of the picture credits.. One of the names should stand out to you,, if your worth your salt.....Guess what he use's? Still today.....Jack's,,,period!
Easy peasy cure to the problem is to simply run your veg nutrient for 2 weeks and then start the Bloom nutrient. Sometimes this still ends in a situation that some think is too early a yellowing/color change in the plant.
I find most nutrient lines to over use P and some at almost a criminal rate.
"Boosting" P&K out side of a nutrient line that actually employs one in their line...Not a great idea. Some lines that do, way overdo it.....I'll endorse Canna, and Hesi as being lines that use a "booster" effectively,
AND chart for it
correctly! Adding more N at this point? Too late and adversely effects THC production.
Yet it should be noted that high K and Mg levels will reduce THC production too. Might add some K and Mg but, as a sulfate and at rates not effecting that issue...I'm after that S...
Anyway, You can see this problem in the Plant Issues section at this site all together too much..Hell, Ben used to preach the same thing to the choir! "You don't have low N. Just stop bloom foods with high P." I got tired of the section for the same damn thing over and over...
As far as run off pH being a good way to test soil pH...I cry BULL SHIT!
#1: Soil drops and rises in pH as it's wet to dry. At what point in this swing did we water again? How much of a variable has now played into your run off pH from this FACT?
#2: Now to the big point on this run off pH and soil thing....
Soils self pH's! Unless your in-going solutions are over 8.0 or under 5.0......Who cares? The soil will self correct....
Soil has a basic pH when built, We add forms of Ca for buffering and for the plant.... As the soil cooks.. It's settling in on a pH that will change once a plant hits it.
That's right, the plant in the soil helps set the soil pH to where the plant stain likes it....This is part of the soil food web of organics
Now we learned that when you water. The soil drops in pH and this can be over a whole point...As the soil dries back out. It rise's back to it's resting point.
So, it's easy to see that over watering will, eventually, cause a pH issue.
The same is true for watering with a too high/low pH solution as it can, and will overpower the buffer in the soil in time. Can be quicker then some think.
So run off metering be new to me? Not at all and NOT accepted by me at all. Too many damn variables...NO organic grower worth his salt will ever care about soil pH - If he built his soil right!
BTW, I organic farm. Have for ever, Ran greenhouses and a massive Yew farm for cancer drug production (till they figured out how to "grow" the chemical faster and cheaper in a test tube.)
No soil grower should ever rely on run off pH and any math formula to be near as accurate as a proper meter. The industrial standard of HANNAH HI98168 or the HI99121 direct soil meters. I Guarantee your not metering with a .002 accuracy! Not that you need to but, we have both on the farm for field testing...
I have heard of a $129 HANNAH soil probed meter doing well. I can't fully endorse it, because I haven't tried it. Yet some of the good words are from some I trust...
I have one in my grow (99121) and I bought a liquid probe and recalibrated for that as I test solutions
in-going and ignore "soil" pH.....YES, even for synthetic runs...SOIL, SELF pH's!