Hello Mark,
After discovering im in a very similar position as you. As in Nov/Dec 2017 ive spread a surface mulch about 4-5inch all over my two 60M2 poly-tunnels. Spinich and mixed mustard greens and spring onions planted in Sept2017 had been growing along not to bad. Although with hindsight the spinich was much more wrinkly then should be i just put that down to the extreme cold winter we have had. But as soon as potatos and peas sown in late Jan2018 started to come up i realized something was wrong. Peas worse then the worse in your previous photos and potatos that had no normal leafs only what looked like spring time fern leafs. So for the last week i have been moving this 5tons of AP contaminated manure from my tunnels. The first bed i cleared i broadforked and raked before soaking with water hoping to get the results Dow recommend for the soil mircro organisums to do there work. But after a comment from Charles im thinking of not broad forking and just removing as much as possible by hand. On the 2nd bed ive went so far as to use a floor brush to get any physical trace off. Only 8 more beds to go and i can start on the outdoor beds followed by herb beds and 40-50 fruit trees. But i was wondering as you have had this problem since spring 2016 could you post a comment on how you think things are going this year Spring2018 like can you grow sensitive crops like tomato, potato and peas. It would really help to keep me motivated in this task of removing 5tonnes. Because some forums and internet reports say people are still having trouble after 5 years but they dont say if they are no dig or more details on there situation. Your story is the one i found witch i feel i can relate to.
Great work on all your research.