Indeed it was a home staple, why 51% of the corn grown in the US in 1860 was from the slave states.
The strength of a slave economy in agriculture would seem to have to been its versatility, not only could it virtually dominate labor intensive segments of agriculture such as Cotton, Sugarcane, Rice, Hemp,and Tobacco production, but do it while also remaining self sufficient in production of other areas such as foodstuffs, also it lended itself to clearing land for expansion as well.
The one that really surprised me a bit was wheat, its normally considered a northern cold climate crop, yet even 28% of US wheat production was coming from slave states.