ear to the ground vs know-how

ear to the ground

noun
  • Pursuing the practice or having the characteristic of carefully gathering information; well-informed. 

  • The practice or characteristic of carefully gathering information; a state or mindset of attentiveness. 

know-how

noun
  • The knowledge and skill to be able to (do something correctly). 

How often have the words ear to the ground and know-how occurred in a corpus of books? (source: Google Ngram Viewer )