Hi there!

I have a question please - I recently repotted my citrus tree to much larger pot and to drive worms out of the soil, I used a mixture of water and mustard powder (I saw this in one of the BBC documetaries) - could this somehow affect/damage the plant or lower/increase the soil PH? Maybe it is a stupid question, but it just laid on my mind.

Thank you for any answer.

The usual agents for adjusting pH are lime, dolimite to increase, and sulphur, iron sulphate or maybe acetic acid to decrese.
Mustard contains organic compounds, probably not as pH reactive as above.

At some level mustard is probably going to be toxic, damaging to roots, but I think you would have to be excessive to reach that level, and probably more so to adjust pH significantly, compared to lime or pure sulphur.

That said, mustard can burn skin, and has a strong immediate reaction that weakens over time, that may damage roots.
I would be cautious with seedlings and small plants.

I think any serious damage effect is going to show up pretty quickly,
ie wilting or leaves with brown splotches or turning white, and containers could be flushed out toremove the mustard compounds.