Definition of "durt"

In filthy durt, and left so in the loathely soyle.

1596, Edmund Spenser, “Book V, Canto IX”, in The Faerie Queene. […], London: […] [John Wolfe] for William Ponsonbie, stanza 33

[C]an this durt draw us / To ſuch a ſtupid tameneſſe, that our ſervice / Neglected, and look'd lamely on, and skewd at / With a few honourable words, and this, is righted?

c. 1616–1619 (first performance), John Fletcher, “The Loyal Svbiect”, in Comedies and Tragedies […], London: […] Humphrey Robinson, […], and for Humphrey Moseley […], published 1647, Act II, scene i, page 31, column 1