South died Wednesday at his home in Buford, Ga., northeast of Atlanta, said Butch Lowery, president of the Lowery Group. The company published South's music. Marion Merck of the Hall County coroner's office said South died of natural causes stemming from a heart attack.
"The Grammy Awards are a very nice gesture by the record industry, but they can really mess up your head," South told Times rock critic Robert Hilburn in 1970, months after he accepted the honors for "Games People Play."
"The Grammy is a little like a crown. After you win it, you feel like you have to defend it. In a sense, I froze. I found it hard to go back in to the recording studio because I was afraid the next song wouldn't be perfect."
He struggled emotionally after his brother, Tommy Souter, committed suicide in 1971. Drug abuse derailed South's career, and he disappeared from the stage and recording studio while living in Maui in the early 1970s. His first marriage ended in divorce, and he made comeback attempts to little notice.
He eventually went through drug rehabilitation programs and married his second wife, Jan, in 1987.
Born Joseph Souter in Atlanta on Feb. 28, 1940, he began playing guitar when he was about 11. He was later signed to a recording and publishing contract by country music disc jockey Bill Lowery.
In 1958, South recorded his debut single, a novelty song called "The Purple People Eater Meets the Witch Doctor." His hit song-writing abilities were next on display in 1962 when the Tams reached No. 1 with their R&B recording of "Untie Me."
South worked as a session musician for a time, playing guitar on Aretha Franklin's "Chain of Fools," Bob Dylan's "Blonde on Blonde," Simon and Garfunkel's "Sounds of Silence" and albums by Eddy Arnold, Marty Robbins and other country, R&B and rock bands.
South was an inductee in the Nashville Songwriters Hall of Fame and the Georgia Music Hall of Fame.