Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
stercŏrātĭo, ōnis, f. [stercoro], a dunging, manuring, Varr. R. R. 2, 2, 12; Col. 2, 1 fin.; 2, 16, 2; Plin. 18, 23, 53, § 192.