Too much rust in the soil?

[SarzWix]

One of our beds seems to have been built (not by us!) on top of a former dumping ground/bonfire site; every spade full turns up the remains of some piece of metal - old hinges, screws and nails, unidentified rusty lumps and even a set of old bath taps . Last year I took out as much of it as I could, added a few bags of spent mushroom compost and dug it in, then planted some spuds in it. They didn't do very well.... Only 6 came up out of a dozen planted, and they didn't look very well The yield was pitiful, and they looked a bit scabby.
I did test the soil with a probe before planting, and it was fairly neutral so I thought it'd be ok? Does an excess of rust prevent nutrients being taken up?
And, what can we do to the soil to improve the prospects this year? Or is there anything that would cope with the conditions better than spuds did?

I've got about half a dalek of compost that I can add to it, but other than that I can't really afford to add anything but fresh-ish manure or straw!

[Snadger]

Scab is usually caused by alkaline soil............ Woodash is alkaline................ Why not try brassicas which should thrive in it?

I inherited a similar area on the first plot i had. This was a communal burning area for the whole allotments and as you say, there was loads of metal rubbish in it. I turned it over and and planted spring cabbage in it. They thrived and this was the only area on the plot I could grow brassicas as the clubroot had been burned out of this area only!

[SarzWix]

Thanks Snadger I could do that by rotating anti-clockwise, instead of clockwise. It's only the second year on this plot so it doesn't matter which way I go. I'll put the compost on it anyway, and add whatever I can in the autumn too. Hopefully it'll be fit for something else by next year!

[Hazel at the Hill]

Posting as an opinion, not fact, you understand...

Given that digging the entire lot out and replacing with new topsoil is unlikely to be an option (JCB anybody?) I guess that you are going to have to improve what you've got gradually - by bunging in as much compost/FYM as you can (which will increase the acidity, I believe)

If Snadge is right about brassicas thriving there (and I have every faith), then you could also try legumes in that area which like a similar growing habitat, with the added advantage of adding nitrogen to the soil.

Obviously dig out the ironmongery first ...

[Paulottie]

The problem with the spuds was possibly the lime in the spent mushroom compost. Generally you give iron to yellowing plants(often acid lovers). I doubt iron is the problem. All those fires may have meant good potash levels. Try a fruit crop.

I do love conflicting advice!!!

[SarzWix]

Thanks

Well, I did take out as much of the scrap as I could last year, although the nails and screws are mostly still in there!
I think I may have to invest in a proper testing kit to find out which way the soil has gone... I did test it with a probe type tester, but they're not always accurate are they?
In the meantime, I'll get OH to spread the compost on it