slitch

This would be the properest Manure for their Sandy Land, if they spread it not too thick, theirs being, as I have said, a shallow sandy Soil, which was the Reason I never advis'd any to use Lime, […] But as most Lands have one Swamp or another bordering on them, they may certainly get admirable Slitch, wherewith to manure all their Up-Lands.

DeBow's Review (James Dunwoody Brownson De Bow, Edwin Bell, 1858), volume 25, page 206, quotes this and glosses slitch as "marsh-mud"