Well, if you think that wood chip/sawdust absorbs Nitrogen, fertilize more with nitrogen. Plants with poor nitrogen will be pale color/yellow.
But do it gradually not to burn the plants.

Apparantly the load had a lot of wood shavings (maybe other stuff) than manure.
Otherwise no matter how much nitrogen is tied up with wood fibers there should have been some available for the plants.

The Soil and compost forum is likely to have people who can give good advice.

My experience, offhand, is that it will take one year. It might be ok for lettuces in the fall, depending on how the summer goes. Your mileage may vary, but there it is. I have compensated by planting legumes, planting potatoes, etc., but if your plants are already in? I just muddled through. I am kind of a "little at a time" person. Your situation sounds pretty extreme.

Your consolation is that next year will be great.

Is there any way you can shovel it out and start over, and use the horse manure for a compost pile (letting it sit til next year?) There's still plenty of time in the season, and for what you've got now for cukes, new ones would catch up quickly for you.

Check freecycle to see if anyone has compost that they want to get rid of, or put up a want ad to refill your beds. At minimum, perhaps simply dig out a good sized hole of the horse/shavings blend, and refill that hole with something decent...to avoid shoveling out the whole thing. Perhaps that would be enough area to supply your plants for the season?

It is fixable. Sprinkle some urea, say 1 lb for 500 sqft, and water it in right away.

I agree with cyrus_gardner, give the plants regular feedings of a liquid fertilizer like Neptunes Fish Fertilizer or if you use chems something like Miracle Grow.

Jon

Are your plants showing signs of N depletion, or are they just not visibly growing? Often plants will seem to be doing nothing for several weeks after planting out in the garden. Sometimes they just need some time to adjust and put down strong roots.

I wonder if the shavings really were fresh. I mean, why go through the trouble of mixing aged manure with anything? But it would not be odd to find that bedding, in the form of wood shavings, was picked up with the manure when it was collected from the stalls.

We heat with wood and have it delivered by the pulp cord. That is 10' lengths. We cut and split it ourselves and as a result have a steady supply of wood shavings, chips and sawdust. All are used in my gardens and in my containers. It is aged outside for a year or so and I find that it is better than peat moss for aeration and drainage, while retaining moisture. Topped off with a little chicken or rabbit sh't and I have never had a nitrogen problem.

If your plants aren't yellow, just give them a little time.

What else did you mix in?

Maybe the soil is too compacted.