Question about organic phosphate vs chemical phosphate

[DirtMechanic]

So I was planting some sky pencil shrubbery with Grotabs starter tablets and in the instruction it says specifically that chemical or man made phosphates are to be avoided as they kill the Glomulus and Tricho in the tabs. So is it mainly (haha) the phosphate that are the real problem with man made fertilizer and maintaining preferred biota? I have not really read that fact specifically and am very curious now about a variety of products such as N-0-K types used on grass.

 

[Chuck]

My knowledge is limited as to organophosphates and their uses because I never use any of them. But, here is what I know. Organophosphates are made from natural organic rock phosphate by somehow using sulfuric acid which changes the rock phosphate into phosphoric acid. This type of concoction is used in synthetic/chemical fertilizers. Other types of derivatives from this chemical magic are pesticides of all kinds including Sarin. So, being rather destructive to animal lifeforms, I am quite sure that lifeforms as simple as fungi are severely affected by this modern chemical wizardry. We could go on about the nitrogen used in chemical fertilizers but that will be left for another day (and thread).

 

[NigelJ]

Fully agree about avoiding organophosphorus compounds.
Grotabs contain mycorrhizal fungi, which help the plant roots absorb nutrients. These fungi are sensitive to high levels of phosphate (typically from fertiliser) in the soil. Slow release fertilisers such as bone meal etc seem to be ok. Some South African and Australian plants require very low phosphate levels to thrive.

 

[Chuck]

My knowledge is limited as to organophosphates and their uses because I never use any of them. But, here is what I know. Organophosphates are made from natural organic rock phosphate by somehow using sulfuric acid which changes the rock phosphate into phosphoric acid. This type of concoction is used in synthetic/chemical fertilizers. Other types of derivatives from this chemical magic are pesticides of all kinds including Sarin. So, being rather destructive to animal lifeforms, I am quite sure that lifeforms as simple as fungi are severely affected by this modern chemical wizardry. We could go on about the nitrogen used in chemical fertilizers but that will be left for another day (and thread).

Sorry, I got so interested in man made phosphates that I forgot to answer dirt mechanics question. There are two types of natural phosphates, hard rock phosphates and soft rock phosphate. The hard rock phosphate is what the chemical companies use to perform their magic. Soft rock phosphate aka colloidal clay is mainly what we organic gardeners use. Hard rock phosphate has a higher NPK value than soft rock phosphate, around 15. Soft rock phosphate is usually around 4. Using too much phosphate/phosphorous is very detrimental to plants. It stops a plants ability to uptake some trace minerals, mainly iron but a few others as well. And we all know what a lack of iron does to a plant..

 

[NigelJ]

One of the things to remember about phosphate is that the sodium and potassium phosphate salts are very water soluble, these are commonly found in manmade fertilisers and while the solubility allows plants to readily take up the phosphate it also means that they wash through the soil into drainage systems and natural water courses, causing algal blooms and vigorous growth of waterside plants. One of the big issues in water treatment is removal of phosphate to prevent contamination of natural water resources.
Other than the sodium and potassium salts phosphate salts are a pretty insoluble bunch for example calcium and magnesium phosphates; this insolubility means that they don't wash out the soil, but are less available to plants which is where mycorrhizal fungi come in.

 

[DirtMechanic]

I have read articles in which graphs contrasting "available" phosphate in soil against the pH of that same soil showing low pH and neutral pH phosphate available levels as being greater. I do not recall the nature of the phosphate, and assume it was earthen in its nature. If little is needed, why the fuss? I suspect more is needed than the soils give at certain pH but not at others. Also, are phosphates generally alkaline?

 

[NigelJ]

Phosphates are generally around pH7 (neutral), they are used for buffer solutions between pH4 and pH8 in laboratories.Both low and high pH limit the amount of phosphorus available for plants. It appears that the ideal soil pH for phosphorus availability is 6 to 7.5 see https://www.google.com/url?sa=t&rct...2_053254.pdf&usg=AOvVaw2rOlpF4CVmqV_YktrTlWRe

 

[DirtMechanic]

Thank you @NigelJ, I will be interested to spend some time on that link later in the week.