How big is the garden, and did they actually give you the pH?

I'm putting in beds, 4' x 25'. pH is 5.43

Your ph is perfect! Dont use peat moss, for any soil really! :) I would suggest to use good compost. When you have good compost and "living" soil, ph is not an issue, and will further buffer. Reports show with the micro life in the soil from adding compost allow uptake of every single macro and micronutrient even in soils with ph of 8. This was some study I saw somewhere reading around. It was somwhere they farmers never checked the ph or really knew what ph was. They used biochar and ash to fertilize the field. They found the composted manure they where also adding, buffered the high 8.5 ph of the ash that they where so heavily adding!

Do you want to stay 100% organic? If so you may want to source all those things you listed-kelp,greensand,ect.. If not just use the funding for compost and some synthetic time release fertilizer or CRF with all needed nutrients- like Osmocote plus. The use of compost and organic material will add and build your soil, and give soil life buffering the ph like I talked about. The synthetic time release will not harm microlife and will cover any missing nutrients.

I have some rows I use composted leaves only. I use all purpose miracle gro 24-8-16 when ever I see plants getting green-yellow from N deficiency. This system works great and has yielded me great results this season.

I am not a potato expert but apparently pH 5+/- is a good range to prevent potato scab. They will grow at higher pH as well.

Your Ca:Mg ratio seems to be low, based on what I've read in this forum. That fits with the finding that Ca is below optimum, but Mg was optimum. My pH question was leading up to what form of Ca to add to increase the Ca level to where it needs to be, while getting the desired pH effect.

If you want to keep pH where it is, use gypsum (calcium sulfate). Lime would raise the pH, although with such a low pH you could probably add enough lime to get where you need to be w/o raising the pH that much. If you use lime make sure it is calcitic lime and not dolomite, which has magnesium in it.

I'm surprised the lab didn't make a recommendation for amending in lb/1000 sq ft. You might ask them if they can provide that for Ca.

Sorry, my bad. Just reread the report, looking for the calcium recommendations. That's where they say to use 40 lbs/1000 sf of calcitic limestone. But wouldn't this be the same as liming the planting bed, which would be bad for potatoes? That's why I hesitate to do that.

I have grown potatoes for decades and if I were you I would not add anything beyond possibly leaf compost or such.

Plant and see what happens so you do not do things that could go bad or are a waste of time.

Sandy soil is fine but that depends on how much moisture you normally get.
I would plant deep, six to eight inches and put some type of mulch, leaves or bailed hay or straw, over the plantings to keep moisture in.

RpR that seems too simple, o wait, that is because it 100% great, true advice!!! :)

I have learned so much from seeing how well using compost like leaf mold works. I do use synthetic fertilizer to fill in any gaps when needed though, so I cant say my harvest is 100% organic....

Robbie, you're correct, that would be liming. The test didn't say it was extremely low, just below optimum, so it's not a huge problem.

One thing about good compost is that it's loaded with available minerals. It not only contains minerals from the original plant matter, but it provides an environment that makes minerals available. I've been adding compost for 20 years to my clay, and the tests show it's high in pretty much everything.

When you submitted your soil sample did you tell the lab that you wanted to grow potatoes? Was this soil test done by your state university or another soil testing lab?
If done by your state universities Cooperative Extension Service you can ask your county horticultural agent about whether to add anything to change the soils pH.