It’s spring planting time so consider this concoction for a productive and entertaining farming experience: take one part soil, add two parts artist and mix in more than a little rock’n’ roll. That’s the formula for Cheri Knight, a singer-songwriter who works the land on a 25-acre organic farm in Whately, Massachusetts. When she’s not out touring the country with her band, that is. Ms. Knight has just released a new CD recording she calls: “Northeast Kingdom.” Recently, her tour passed through Boston, and we brought her into the studio to talk about the connection between her music and her farming.