Is there any benefit to adding it to my garden?

Currently, my soil is hard orange clay with an acidic soil of 5.5 to 5.9. It is also very low in phosphorus.

Thanks in advance!

But rust is iron oxide--one of several compounds that form between iron and oxygen when iron oxidizes. Iron oxides are sometimes in the micronutrients in fertilizers.

So I don't believe that one can say that it won't ever be of benefit in a soil. Though if your soil is already orange I would wonder what is causing the orange coloration--iron oxides maybe?

I'll try to figure out what the geotechnical makeup of SC soils are next week. In the meantime here's a document that discusses applying iron to soil.

Rusts are ferric hydroxide : Fe2O3.H2O or similar. The technical paper below lists ten different forms of ferric hydroxide.

Goethite is the most common rust on rusty steel parts, according to the article below.

Compounds don't necessarily stay in one state after the chemical change. They can, if conditions permit undergo further chemical changes.

The Wisconsin extension office article states that if microbial activity is sufficient to decrease the oxygen supply in acid soils, some ferric iron oxides and hydroxides will be transformed to more soluble ferrous forms.

I think that it is more accurate to say that none of us really possess the knowledge to state conclusively.

I will ADMIT that I do not know the answer conclusively. You are going to have to study some of the technical papers and decide for yourself.

Some potentially useful evidence comes from the degradation products of contaminants in soil showing that products of anaerobic degradation are found to an extent even in aerobic soils (or subsoils) and this implies that there are reducing microsites present. This at least suggests that oxidized iron might become reduced and available in such sites too. It would be an easy potted experiment using iron deficiency as the indicator.

Oh, God. I SO have to try that now.

I usually just carry the cutworm off to feed it to my chickens, but this sounds like a much more satisfying outcome. Thank you for the idea!

With my own sets they don't bother them. I believe the reason is that I harden my plants from day 1 when possible and the stems are tough so the worm is buffaloed.

So, putting a bunch of rusty metal in the ground will probably not make much difference one way or the other. It's like adding a bucket of water to a tank that has a very small pipe coming out of it. The output isn't going to change much.