slitch
Fine mud; silt; slake.
rare, uncountable
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"
Where it comes from
From Middle English slicche, from Old English *sliċ, from Proto-West Germanic *sliki, *slīk, from Proto-Germanic *slikiz, *slīką, from Proto-Indo-European *sleyg- (“to be slick; slide, slip”). Related to Dutch slijk (“mud, mire, slush”), German Low German Slick (“mud, silt”), German Schlick (“silt, mud”). Doublet of sleech.
Adapted from the Wiktionary entry slitch (CC BY-SA 4.0).