Asparagus angst

Hi - I'm new here. Really happy to find a forum with so much evident expertise 
Can I ask advice about my new asparagus bed please? I planted my one-year-old crowns this spring in trenches with loads of composted horse manure at the bottom and then a ridge of soil. The soil on my allotment is chalky and well-drained. Each crown has put up a single thin stem (of between 10" and 2-foot). I don't know if this is normal for this time of year in the first year.
However, I realise I have made a mistake. The manure I used came from a local stables and it is wood-chip manure. Everything else on the the allotment is struggling a bit, especially the courgettes that I planted very rich, and I now realise the wood chips in the manure are depleting the nitrogen. Can you please recommend a product I could use to help my asparagus get well established despite my mistake? I'm wondering whether phostrogen, ammonium sulphate etc.?

Thank you.
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