yep sedge rice hull release silica as they break own , they do take a long time to break down though , you can use them for aeration in soil mixes
you can use NTS Potassium silicate reasonably regularly , can be used to help emulsify oils for pest spraying , need to be a little careful with bottled silica , i think i read it's used for steel cutting & in some cases collected after cutting , bottled & sold to the Ag industry , not sure if that's still the case
silica helps to strengthen cell walls making it harder for bugs to penetrate , what were you looking at it for
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aloe is always a good plant health tonic