According to many experts, Sargassum makes an excellent fertilizer. However, I would definitely want to wash it down thoroughly before using it in my garden.

It will be covered in salt which you know is not conducive to the good health of most plants that do not grow directly near the sea.

If you have somewhere to spread it, hose it down and let it dry, that would be my choice. I would also prefer to pop all the polyps (the little round things that make Sargassum float and which contains the noxious odor) before bringing it on my property.

Depending upon the quantities used, you could do this by stomping on it or using something like a front end loader bucket or bobcat bucket to squish it.

I'd mix it with about 60% top soil and 40% Sargassum ... then dig it in around the garden. You don't have to dig deeply, just enough to be certain it is covered and will break down well. It should make a really good loam.

I haven't tried it as I have no access to any large equipment and nowhere to spread it other than on my lawn and that would likely damage the grass.