Let the Soil Play Its Simple Part is an album of songs written and performed by Caroline Shaw and Sō Percussion. The musicians, who have known each other since their student days, were presented with three days of gratis studio time and decided to experiment with ideas they had begun putting to tape during the sessions for their January 2021 Nonesuch release Narrow Sea. With Shaw on vocals and Sō – Eric Cha-Beach, Josh Quillen, Adam Sliwinski, and Jason Treuting – filling out this new band, they developed songs in the studio, with lyrics inspired by their own wide-ranging interests: James Joyce, the Sacred Harp hymn book, a poem by Anne Carson, the Bible's Book of Ruth, the American roots tune "I'll Fly Away," and the pop perfection of ABBA, among others. The album is co-produced by Shaw, Sō Percussion, and the Grammy Award-winning engineer Jonathan Low (The National, Taylor Swift).

Shaw, who won a Pulitzer Prize for her vocal composition Partita for 8 Voices, written for and performed with Roomful of Teeth, makes her solo vocal debut with Let the Soil Play Its Simple Part. "I hadn't written very many songs, but I have certainly loved many in my life. I've been thinking of making a solo album for seven or eight years, but it takes having the right friends and community in the room," Shaw says. "The prompt for all of us was: What would we make in the room together with no one person in charge, like a band writes in the studio?"

"Some songs on Let the Soil... were very specifically composed by Caroline," Cha-Beach says. "But others were this assemblage of ideas: finding words, an idea for how a melody could work, a harmony, and then tossing it in a blender and trusting each other." Shaw adds, "What I love about Sō is the curiosity about how objects make sounds and how they speak to each other. [There was an] underlying thread of thinking about what goes into soil, how we take care of it, how we allow it to be itself, how we contain it, and what can come out of it if you cultivate the right environment, which for me is always this wonderful metaphor for creativity and collaboration: let people be themselves and see what happens."