Willie Nelson, reigning monarch of American music, offers part of his domain to collaborator Ryan Adams on his new album “Songbird.” The project is colored a little by Adams’ rock music but mostly by Nelson’s cultivated voice. Adams’ backing band, The Cardinals, definitely rocks Nelson, but the country always shines through. After all, His Highness wouldn’t let just any young buck encroach on his territory.

The record contains one new Nelson song — the wispy and wistful “Back to Earth” — and three previously recorded Nelson originals — including the opener “Rainy Day Blues,” a self-identifying bread and butter tune. The Adams-penned “Blue Hotel” conforms more closely to Nelson’s style, while Nelson’s songs venture into Adams’ neighborhood. A true collaboration, the album sees Nelson trade his cowboy hat for Adams’ electric guitar.

It’s comfort music — simple, homemade and easy to digest. Most songs are classic covers, cut in Nelson’s cowboy style with plenty of harmonica and steel guitar. Such standards from country’s songbook include a poignant rendition of Leonard Cohen’s “Hallelujah,” the religious and sexual themes of which are dissonant with the more common ideas of love and loss on the rest of the album. More spirituality is found in “Amazing Grace,” performed to great effect in a haunting, crawling minor key. Nelson also adds to the country sound to the Grateful Dead’s “Stella Blue,” which drifts bluesily along, buoyed by Adams’ emotive guitar tremolos. “$1,000 Wedding,” textbook alt-country, chronicles a jilted groom: “I hate to tell you how he acted when the news arrived/ He took some friends out drinking and/ It’s lucky they survived.” Good, simple stories for good, simple music.

Holistically, though, the record falls short in its squeaky-clean production. Adams, the record’s producer, makes the cuts sound too pop-ish, a lacquer poorly suited to the bucolic and the bluesy. Every song plays like it was recorded in a state-of-the-art studio (Loho Studios in New York, to be specific) instead of on a long, lonely highway (alas, as it should have been). Willie’s other major album this year, “You Don’t Know Me,” benefited greatly from its retro-sounding production, and Nelson should have insisted on similar treatment for “Songbird.”

In recent years, Nelson has worked with an unusually large number of young artists. Whether bored of his roots or trying to attract a new audience, in the last decade he tackled a reggae project, an album of jazz instrumentals and a tribute to songwriter Cindy Walker. “Songbird,” with 31-year-old Adams, continues that trend. “It’s a different sound than any other album I’ve ever made,” says Nelson.

Although different, Nelson’s newest addition to his 250 recorded albums and 2,500 written songs is just that — another 12 tracks to a musical stockpile as high as the country sky. If you’re itching for Nelson, I would recommend “You Don’t Know Me,” an effort far truer to Nelson’s place in Americana. As Dan Rather suggested, “We should add his face to the cliffs of Mt. Rushmore and be done with it.”