Sounds like the lasagne/cover crop process made a huge difference. Your pH is now neutral instead of high. I'm not sure what 'volatile organic content' is but it's probably what we generally call organic matter content, and that's a great number so you've obviously gotten organic matter into the soil.

I am not sure why they would recommend putting in more soil, that stuff sounds fine to me, but it's water under the bridge if you've already done it.

Did the lab recommend ammonium sulfate? You didn't say where that idea came from.

It seems to me if your cover crop grew 4 ft. high you aren't in need of nutrients. N goes up and down seasonally, too.

Question:

If you were able to grow a cover crop to a height of four feet, what was the color? Was it dark or light?

If dark, you are in good shape. If light, nitrogen was deficient (most likely).

I'm going to guess that if you were able to grow a cover crop to 4', you are just fine.

Dark or light? Mmmm - LOL I don't know, it was green, but yeah most likely light to medium green. Uhm, I guess I was concerned because I know to break down the raw organic content (i.e. the cover crop left at the surface and its roots to include radishes) nitrogen may be depleted. Am I over thinking this?

If I don't pull back the black plastic and compost now to add ammonium sulfate, perhaps just add something like feather meal or fish emulsion when I actually begin placing plant material in April or May?

How well soil tests do with measuring Nitrogen levels in your soil depends on the temperature of your soil, and the activity of the Soil Food Web. Low levels of organic matter affect the activity of your Soil Food Web because they feed on that organic matter.
Ammonium Sulfate is a very readily available form of Nitrogen that is known to flow out of the soil about as rapidly as you add it and will pollute the ground water and eventually the water you drink.
It may well be that your soil was too cold for the SFW to be very active when the soil test was done.

The high amm. sulfate recommendation may have been due to the low N AND high pH in the lab results. The reason for amm. sulfate in particular may be because, of all the N source fertilizers, amm. sulfate is the most effective for lowering pH on a pound for pound basis.

I'm curious how you took both the first and second samples, particularly the depths. How soil samples are taken is crucial to getting meaningful lab results and avoiding misleading results.

The cover crops are certainly a good idea, especially the Diakons in your heavy soil.

When cover crops are being broken down, nitrogen is tied up for a while, but released back later in the season.

Some nitrogen at planting gives things a shot in the arm. What form of nitrogen you would use depends on your level of how organic vs chemical you want to be.

"Ammonium Sulfate...will pollute the ground water and eventually the water you drink."

A sweeping statement that may be true in some situations but certainly not all.

Thanks all. I thought because I read about ammonium sulfate in a Sunset Garden book it would be a good thing - maybe it was an old book.

The lab recommended laying the compost on top of existing cover crop now and then to add feather meal when I plant in April or May.

As for how I took the samples, I used a soil probe. The first sample was in the late spring or early summer, this last one was perhaps 1.5 to 2 months ago. I thought it might be too cold but the lab suggested I do it now to get a head start.

So, what do you think?
a) Leave everything as is - that is 6 inches of forest loam compost on top of cover crop covered with black plastic from now until say March, then do another soil test.
b) Leave as is and just "let it rip" and plant?
c) Add nitrogen now . . ?
d) Other

I really doubt that your soil is lacking in nitrogen. The cover crop would not have been successful, growing to 4 feet tall, if you had real soil deficiencies.

Your vetch and legumes will also have "fixed" additional nitrogen in the soil with their roots. That will be available to other plants as the legume and vetch roots decompose. You've already got that process started by cutting everything down, layering compost on top and covering it.

The only thing that I would do at this point is perhaps replace that black plastic with a landscape fabric that is permeable to air and water. In order for the soil life to get to work breaking down your cover crops, they need air, and they need a little water. The black plastic left in place could have some negative effects on the soil life.

Then in March or so, I'd mix in a little blood meal as you plant, depending on what you are planting. Leaf crops like lettuce and spinach get a little more blood meal, fruiting crops like tomatoes and peppers not so much (too much nitrogen grows great foliage at the expense of fruit production!) and radishes little to none at all.

The change in pH from 7.75 - 7.03 in 2 years based on what you did in that interval is a bit perplexing unless your soil is not very buffered. Dense heavy clays would be pretty darned buffered so, what gives? that's why I asked about your sampling method, a possible explanation. Did you sample the same depths and do multiple locations in your planned planting area, then composite the samples both years? Did both samples get sent to the same lab?

The probe was an excellent idea, doubt it was a factor in the results.

Landscape fabric instead of black plastic, agreed. Too bad it costs a lot more.

If you want to know what the N status of your soil is, sample before you add any N containing material, otherwise, how would you know how much you may need to add for the coming growing season? If nothing else, sampling now will give you a good idea of what happened as the result of what you did last year, a good thing to know.

Remember, the organic N sources, blood meal, feathers, your turned in cover crop, etc. will not provide plant available N in the cold soils of early to mid Spring as the soil micro organisms that convert all that organic N to nitrate will not be too active. If you grow early stuff like broccoli and lettuce this could be a problem if the nitrate isn't already there from the previous season (a new soil test taken now will tell you that), otherwise, if you are going for later crops only, the soil critters may well have converted all those organic source goodies to available N. by planting time.

I know Michael357 what you are saying, I had thought to get another opinion from another soil lab but . . . phhht at some point I just gotta plant and I have the "feeling" it will be alright as most future plantings have ph requirements between neutral and acidic. Yes, to all of your questions.

Aaugh to the landscape fabric - Gosh that black plastic was expensive enough. Whew! But yeah, gotta do it right so I'll go get the landscape fabric tomorrow and Thank You for this valuable insight! I used the black plastic intending to keep the cover crop from growing through the 6 inches of compost - it was already starting to poke it's head through. Any idea where I should look for this and is there a brand or type that is better than another?

An article in the current issue of Fine Gardening indicates that even landscape fabrics can inhibit air infiltration into soils and strongly suggests that the use of them is not a good idea. The use of a non renewable material such as plastic has been known to be not good for many years.
For those that donot understand nitrate contamination of ground water this link may be of soem help.

Here is a link that might be useful: Nitrate and groundwater

"Ammonium Sulfate...will pollute the ground water and eventually the water you drink."
...
'A sweeping statement that may be true in some situations but certainly not all.'
..........
And is true of any nitrate fertilizer if overused, and thus is essentially a useless statement.