Jesse Dukeminier, author of one of the leading series of textbooks on property, traces the use of Blackacre and Whiteacre for this purpose to a 1628 treatise by Sir Edward Coke.
One of the more basic theories is that Blackacre and Whiteacre are related to what professors could draw on dark chalkboards in early law-school settings.
Law professor K-Sue Park "found that the terms, infrequent but present in English legal treatises, also constituted the title of a proslavery novel that appeared in 1856, the same year the Court decided Dred Scott, from a prominent Confederate press"–William M. Burwell's White Acre vs. Black Acre (1856).
It seems likely that the deployment of these terms by a member of a high-profile political family to defend slavery so publicly at this turbulent time might have had some influence on their popular connotations and meaning, or at least as much as obscure English planting terminology.
[6] A group of law students in Indianapolis founded a brewery named Black Acre Brewing Co. in late 2010 as a homage to their legal schooling.