Nobody here will know. Next have the soil tested and see what the report recommends.

Put some of your purchased soil in a one-gallon pot. Plant some fast-growing seeds in there, like beans or sunflowers. Water only with city water. Give the plants some sun, and let them grow. See what happens.

My very cynical guess is that it's the soil that you bought. Maybe with herbicide from the manure. Check the link below, and google "manure herbicide contamination".

Here is a link to a test you can do: http://www.walterreeves.com/tools-and-chemicals/bioassay-testing-manure-and-hay-for-herbicide-contamination/

Here is a link that might be useful: herbicide contamination

My first thought was the same as lilydude's: clopyralid or other herbicide contamination of the purchased soil.

Here is a link that might be useful: more on herbicide contamination

I am going to try the experiment in the Walter Reeves article that Lilydude linked. I may be able to determine it's the soil without having the expense of a soil test. Thank you for the advice, it's such a simple suggestion, and one that I never would have thought of. I'll post a follow up in about three weeks.

The problem with the soil test is that it usually measures nutrient levels only, not contaminants. I don't know what it would cost to measure herbicide levels. Maybe you could inquire.

In any case, if I were in your situation, and if I found out that the soil was toxic, I would visit the place where the soil came from, and turn the charm level WAY UP, if you catch my drift. If you can't do it, find someone you know who looks a little unstable/dangerous and have them do it for you. Anthony Hopkins would be perfect. He wouldn't even have to raise his voice. I suspect that a full refund would quiet me down...maybe. The problem is that you now have to get rid of a whole lot of toxic soil (assuming that's the problem). Maybe they should take care of that for you also.

I have purchased topsoil with a lot of sawdust in it. It sucks the nitrogen out so bad, newly seeded grass has a hard time being green. With the addition of a high nitrogen fertilizer the problem can be solved. This problem is more prevalent than most realize. Half aged sawdust is a great filler and turns the soil black. Looks good, but way deficient in nitrogen. Composted horse manure has a lot of hay and straw in it that's not usually finished composting.
Selling toxic soil can happen, but the likelihood is rather small in my opinion.

Sure, testing is the way to go, but at what cost in money and time? Will it be done? Like Lilydude says, most tests don't measure contaminants. I can't imagine what that would cost.

Do the Walter Reeves test, but add some with nitrogen added to half of them. See the difference between just water, and nitrogen and water.
Mike

If the problem is sawdust, that's OK, because the soil will be in good shape by next Spring. But they should have warned you.

Gardnerkarin has already been feeding with 20-20-20. It didn't fix the problem. That weakens the sawdust argument. Since plants are already growing in this "soil", I would give them a foliar feed of soluble fertilizer. Or give them some high-nitrogen lawn food, and water it in really well. (Don't use anything with broadleaf weed killer in it.) See what happens. If the plants don't respond, I think that kills the sawdust theory. Besides, the seller said it was half manure, half soil. Ask the seller if there is sawdust in the mix. Ask the seller if anyone else is having problems.

We bought a unit from Sears to remove Iron from the water, I think maybe it uses Manganese in the beads that remove the iron, so I don't know what that does to the Manganese content. It cycles and recharges every week.

I doubt that the iron and manganese are causing this problem. Both elements are essential trace elements for plants. It's true that trace elements can be toxic to plants at high concentrations, but the water tested at 1.07 mg/liter. A liter of water weighs 1kg, so this is a concentration of 1.07 parts per million by weight. The manganese is even lower. I would drink this water all day long and not have a worry in the world. And this concentration is nothing compared to the amount of iron in the soil (1 to 5% by weight, or 10,000 to 50,000 parts per million). Also, both iron and manganese are most soluble and available to plant roots at very low soil pH, 5 or less. Your garden soil should be corrected to the 6 - 6.5 range with lime. Also, this isn't southern California, where salts accumulate in the soil because of low rainfall. Our soils leach like crazy in the winter.

Here is a link that might be useful: iron in soil

We have iron and manganese in our water too and it has not affected any plants at all, so it must be the soil lacking in something or with something harmful in it. I was once told that horse manure compost can be bad to use if the pile sits for a long time undisturbed. Some critter inhabits it and plants can't survive with it. It was over 20 years ago that I was told this, so I don't remember the details.

Lilydude, have you ever smelled water with high manganese? I couldn't drink it if we didn't filter some out.

Hemnancy, I bet you have either sodium or potassium in your iron removal system. You may have manganese in your water since it's so prevalent in the water in our area.

Ratherb, I suspect the critter you are referring to is symphilids. They like soils with high organic content.

The internet is a wonderful thing. From the attached link, adults need around 2mg of Manganese per day. Gardnerkarin's water has about 0.2mg per liter. So to get your 2mg, you would need to drink 10 liters of water. The link says that adults should not take in more than 11mg per day. That would require drinking 55 liters of water. OTOH, "the EPA recommends 0.05 mg/liter as the maximum allowable manganese concentration in drinking water". Sounds pretty conservative.

Here is a good link about Manganese in soil:
http://www.soils.wisc.edu/extension/pubs/A2526.pdf

Here is a link that might be useful: manganese requirement

This is a link to the iron filter sold by Sears. It says it reduces manganese as well up to 5 ppm, and Hydrogen sulfide (rotten egg smell). If you read it you will see it uses Potassium Permanganate as the active chemical to bind the other minerals.

Here is a link that might be useful: Iron removal filter

Follow up: My experiment is turning out as expected. I used radish seeds because they grow so fast and they hadn't worked out well in my garden soil the first time around. So, with 9 pots planted, 4 of commercial sunshine mix, 4 of garden soil, and 1 of 1/2 and 1/2 each, the results show that my garden soil is definitely lacking, but perhaps not full of herbicide. The radishes grew in the garden soil but not very well. They are green, though, which makes me think that it isn't a lack of nitrogen, just something else missing. I plan to remove 1/2 the soil and add lots of compost to each bed early this fall, and hope that this solves the problem for next spring. I also did the test where you put a shovel full of soil into a glass jar of water and shake it up to see the soil composition. I had lots of floating wood bits and the soil in the bottom had a sour smell. One note, after the sun finally started to shine this month, my blueberries, strawberries and raspberries took off, and my beans look pretty good, too. Everything else is still stunted, yellow, and ready to be dug out and thrown on the compost.

I've added a link to photos of my radish experiment which I hope works. It's obvious which ones are in my garden soil.

Here is a link that might be useful: radish experiment

How do the roots look on the plants in the purchased soil? Maybe symphilids are the problem.

Try putting some lime on the plants in the purchased soil. Water it in really well. See what happens.

The roots look the same on all the plants. White and long and hairy. Both the sunshine mix and my garden soil have roots the full depth of the pots. There are no critters in either, except a couple of earthworms in my garden soil. I've limed one of the garden soil pots and have two that I'm going to feed every watering with 20/20/20, and one control pot. Were you thinking that my PH is too low? The garden soil radishes have a red or purplish ring around the edges of their leaves, and the sunshine mix is only green.

The fact that blueberries like it may mean that it has very low pH. If the lime doesn't work, I would go to the seller and request that they remove the product from your property, at their own expense, and give you a refund. Why should you do all this detective work? They probably know why it's so screwed up.

You are right, of course, Lilydude. I'm just not good at confrontation, and so avoid it at all costs. But,I am going to go talk to the owner this week and take my radish experiment with me. I can't be the only one that has had problems with this soil.