I have recently collated a number of 45s containing a political message for the IDR Mix over on Souled On. One of the songs which didn't make the mix was the above.
Wikipedia explains the concept of 40 acres and a mule and why it still has political resonance for African Americans:
40 acres and a mule is a term for compensation that was to be awarded to freed African American slaves after the US Civil War — 40 acres of land to farm, and a mule with which to drag a plow so the land could be cultivated.
By June of 1865, around 40,000 freed slaves were settled on 400,000 acres (1,600 km²) in Georgia and South Carolina. Soon after, President Johnson reversed the order and returned the land to its white former owners.
Because of this, the phrase has come to represent the failure of Reconstruction and the general public to assist African Americans in the path from slavery to freedom
You can read a fuller explanation on Emerging Minds.
Sound Experience consisted of Arthur Grant (vocals); Reginald Wright, Leroy Frailing, Anton Scott, Melvin Miles, Johnny Froman, Gregory Holmes, James Lindsay. They formed at Baltimore's Morgan State College in 1970.
During the early '70s, the group hooked up with producer Stan Watson and his Philly Groove/Soulville labels, and moved to Philadelphia to record with him. Stan Watson attended Glen Mills Reform School in Philadelphia as a teenager in 1952. 20 years later he returned with Sound Experience for a live show that would surface as an album on New York’s GSF label. They recorded two further LPs with Watson; studio sets for Buddah called Don’t Fight The Feeling (1974) and Boogie Woogie(1975). Collectables issued a collection called the Soulville Years back in 1994 and which you can pick up off Amazon etc.
I am currently working on a second mix consisting of politicalised soul songs.