The innoculant. (I am provoked to be my father passing on information!) You can tell if its working by looking at the roots. You can see the nodules where the bacteria cluster.
This has a good picture.
Nitrogen Nodules And Nitrogen Fixing Plants
Nitrogen Fixing Bacteria with Peas, Beans and Family
You mention carrot seeds and keeping them damp. I think that covering a damp seeded row of carrots with a board to encourage and speed up germination is an old farmer's / gardener's idea that you seem to know! My father did it. I think he got the idea from Organic Gardening Magazine back in the 1960s. It does work well if you keep the soil damp. If anyone reading this wants to grow carrots, its worth a try!
Here is Herrick Kimballs website. Go down to his videos of "4 Day Carrots", really, Carrots that he managed to germinate in 4 days!
Whizbang Gardening---4 day carrots
Unfortunately I do not have room or soil depth or cool weather for carrots at my current home. I grew them up north and some in a box with screened dirt here in KS. Varieties I liked were Valerie, Kuroda, and Royal Chantanay. Good luck with yours!
Link is https://freerepublic.com/focus/chat/4320293/Have You Seen My -- or -- https://freerepublic.com/focus/chat/4320293/Have%20You%20Seen%20My