Leonardite, humates and potassium

[myxodex]

From what I can find out humic (and fulvic) acid preparations sold in the plant food trade are solubilised from leonardite by treatment with potassium hydroxide, i.e. solutions are likely to be potassium humates. Does anyone know more ? Does this mean humic acid preparations should be avoided if wanting to reduce potassium in feed ? Apparently leonardite (untreated) is used to reduce metal toxicity for plants in contaminated soils. Anyone have experience of adding leonardite to potting mixes ?

Cheers,
Tim

 

[Rick]

What about adding a small amount of peat moss to your potting mix.

Seems like the extraction of purified humates only requires a high pH (not specifically KOH). So for lab purposes, sodium hydroxide is used instead of potassium hydroxide. You could just as well probably get away with Calcium hydroxide (lime).

Since the agriculture industry is biased towards crop product where extra K is beneficial you may find it hard to obtain a K-less humic source.

But overall the amount needed for orchids is not high, and probably not worth a special addition of a purified extract.

In some ways the composting of bark with lime (as per orchiata bark products) is probably moving in that same direction.

There are also plenty of metals chelating organics in kelp extracts (though most are not true humates). That's what I'm using as an organic supplement.