Slaves are capital, and, like all capital, acquiring and maintaining them has nonzero cost.
In the antebellum American South, some tasks like ditch-digging were sufficiently hazardous that a plantation owner would rather not risk their investment in their slaves, and so would hire Irish ditch-diggers by the day, as the plantation owner would be out less money if they died while digging the ditch.
Somewhat off topic, but I can't figure out how ditch-digging would be particularly hazardous? The only danger I can think of would be a wall collapsing, but that could surely be avoided..
Slaves are capital, and, like all capital, acquiring and maintaining them has nonzero cost.
In the antebellum American South, some tasks like ditch-digging were sufficiently hazardous that a plantation owner would rather not risk their investment in their slaves, and so would hire Irish ditch-diggers by the day, as the plantation owner would be out less money if they died while digging the ditch.