Using soil from dried pond on raised beds

[galtezza]

We have a large dried up 'pond' on our land. It is more of a low lying piece of land where the rainwater, and agricultural water from the neighbouring farmers orchards collects. This area is about 30 x 40 ft and is full of water over winter - but dries out through the summer and is now completely dry and looking quite green and fertile...
http://inlinethumb20.webshots.com/46...600x600Q85.jpg
Our soil is heavy clay, and we are building a number of raised beds for vegetable gardens (easier on my back with a no dig method!). As the price of top soil is quite scary, we are using well rotted manure in the beds to reduce the amount of top soil needed, but wondered whether the soil from the pond would be good to use - if we scraped off the top growth with the JCB? Would it be good for the veggies? Not sure if it would change the pH of the soil, or cause more problems...
Being a newbie to veggie gardener, I am not sure whether I would just be causing more problems for myself by using this soil or not? I will still be putting in some topsoil, but trying to reduce the percentage of bought top soil to the minimum, and re-use what we have got.
Any help greatly appreciated...

[taff]

I'd use it as long as i knew there weren't any pesticides in it [from the agricultural run off]

[galtezza]

Thanks Taff, I have been assured by the farmer that he is 'almost' organic. Not sure what the french would deem as 'almost..'!

[rustylady]

Of course, you do realise that if you use the "topsoil" from the pond you will end up with a deeper hole and therefore a deeper pond, don't you?

[taff]

and thats where hugelkultur comes in
now, you knew i was going to say that didnt you?

[snohare]

Pond soil is normally stuffed full of nitrogen, it should be great for leaf crops. But be careful not to go too deep, as subsoil will have no usable nutrients at all, being devoid of bacteria etc. Although I suppose that might make it good for growing carrots, if it is sandy enough...

[Aberdeenplotter]

I'd use it as long as i knew there weren't any pesticides in it [from the agricultural run off]

Not just pesticides. Possibly also nitrates from run off after artificial fertiliser application

[galtezza]

Thanks guys. I'll speak to the farmer and find out exactly what he uses. He doesn't wear any of the protective suits that most farmers out here use when they are spraying, so I guess he is either using less aggressive chemicals - or he is more blase about his health!
Absolutely Rustylady, one of the projects we still have to tackle, is increasing the depth and width of the pond so we were hoping that taking the topsoil would actually help both projects. We want to make the pond an all year round feature, so hoping a larger deeper pond will retain the water through the summer, and we can then stock it with fish, as well as plants and frogs.