My 5 methods for soil improvement. Thoughts?

Seaweed mulch I collected from the beach. Although it's rinsed I still fear it'll add too much salt to the soil, but hopefully not.

Homemade IMO made from rice under the mulch.

Mushroom slurry using mushrooms growing in my local park. The land's contaminated though so I don't know if that would affect the mushrooms and then my soil negatively. I could delay it until I find another source.

Leaving all weed and plant roots undisturbed but chop n' drop the tops.

Occasional use of worm tea, manure tea, and horse manure.

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I don't want to harm the soil and plants/trees from too much kindness (like when I over-manures my soil last year, resulting in no cucumbers, zucchinis etc.) But I also want to give the best they can have.

The land's contaminated though so I don't know if that would affect the mushrooms and then my soil negatively. I could delay it until I find another source.  

 I would look for another source.  Fungi are used for bio remediation because they concentrate toxins after removing them from the soil/dirt.

Plain old homemade compost seems to work for me. I also now have a bokashi system for fermenting kitchen waste (especially stuff you couldn’t normally put in a compost heap), although that does need to be hidden under the soil.

I also find that perennials are helping to build soil by virtue of stopping fallen leaves and other loose vegetation blowing away.

Tim Kivi wrote:Seaweed mulch I collected from the beach. Although it's rinsed I still fear it'll add too much salt to the soil, but hopefully not.

Homemade IMO made from rice under the mulch.

Mushroom slurry using mushrooms growing in my local park. The land's contaminated though so I don't know if that would affect the mushrooms and then my soil negatively. I could delay it until I find another source.

Leaving all weed and plant roots undisturbed but chop n' drop the tops.

Occasional use of worm tea, manure tea, and horse manure.

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I don't want to harm the soil and plants/trees from too much kindness (like when I over-manures my soil last year, resulting in no cucumbers, zucchinis etc.) But I also want to give the best they can have.

Rinsed Seaweed will not add salinity to the soil, Sea water can be used on farming soils at a rate of 1 gallon per sq. ft. with no ill effects, so use that seaweed.
You can use IMO but unless you already have some decent microorganisms growing in your soil these will end up being the only ones present.
If you only have access to already contaminate fungi, use only the gills (scrape them out with a spoon) to make your slurries, this will prevent you adding contaminants to your soil through the use of whole, contaminated fungi fruits.
Chop and drop plants are great.
Horse or other manures must be composted before you incorporate it into soil in any manner. The option would be if this is fallow (un used at the time) land, then it could be allowed to rot in place, but this is going to take a full year to become ready for planting.

If you haven't already found them, I have given lots of information here The soil threads