Yeah DE is mostly silica BECAUSE "Silica is most commonly found in nature as
sand or
quartz,
as well as in the cell walls of diatoms." DE is not silica as we're talking about, and is not used for this type of application. DE is only used in agriculture for pest removal.
If you read further down in the article that you prob quoted from you'll also find this:
"Diatomaceous earth consists of fossilized remains of
diatoms, a type of hard-shelled
algae. It is used as a
filtration aid, as a mild abrasive, as a mechanical
insecticide, as an
absorbent for liquids, as
cat litter, as an activator in
blood clotting studies, and as a component of
dynamite. As it is also heat-resistant, it can be used as a
thermal insulator.
(Note no listing of use for silica enichment of soil...), and also this:
"Use in agriculture
Natural freshwater diatomaceous earth is used in agriculture for grain storage as an anti-caking agent, as well as insecticide.
[6] It is approved by the US Department of Agriculture as a feed supplement.
It is also used as a neutral anthelmentic (de-wormer). Some farmers add it to their livestock and
poultry feed to improve the health of animals.
[7] "Food Grade Diatomaceous Earth" is widely available in agricultural feed supply stores. It is acceptable as
organic feed additive for livestock."
So basically the DE that you buy for top-dressing your soil, while it is mostly comprised of silica-based organisms, is not for enriching your soils with silica and won't because it is not the proper delivery method for plants. That's why we have silica products on the market, which are designed for a completely different application than DE powder and are also in a different form which allows them to actually be absorbed and used by the plant.
Read the while article next time.