George Washington’s Dung Repository is an example of his agricultural innovative and his letters, and diary entries provide the documentation to better understand the role of this building at the plantation.
While the documentary references to the Dung Repository are not numerous, they provide important clues about the building's construction and use. The earliest reference to the Dung Repository, also referred to by George Washington as the "Stercorary," dates to May 1787. In a letter to his farm manager, George Augustine Washington, George Washington provided typically detailed instructions for erecting a portion of the building:
When you go about the repositary for the
compost, at the mouth of the drain by the
Stable, if the bottom should not be of good
clay, put clay there and ram it well before
you pave it, to prevent the liquid manure from
sinking, and thereby being lost, this should
also be done on the New sides wch. are to
be walled up. Cornelius when he knows for
what purpose this is required will I presume,
know how to do it.
This brief account is full of useful information. First, it corroborates the Vaughan plan in placing the location of the building near the stable. A vaulted brick drain revealed by excavations in the South Grove appears to run from the Mansion to a point near the hypothesized northwest corner of the Dung Repository, and is likely to be the drain in this reference. In addition, the nature of the directions clearly indicates that construction of the repository had begun, but was at an early stage in the process. The finishing of the manure pit itself is the subject of most of Washington's attention in this letter, focusing on how to prepare and pave the bottom. The stipulation that the "New sides" were to be "walled up" implies that at least that portion of the Repository was of masonry construction.
A second letter written the following July indicates that additional progress had been made:
It is indispensably necessary to lay Cills,
and good heavy ones, well morticed together,
on the brick work of the Stercorary; without it,
the walls will soon be down.
The specific mention of "brick work" likely refers to the "New sides" discussed in May. Finally, the Vaughan plan, prepared during a visit to Mount Vernon in August of 1787, depicts the Dung Repository as a long, narrow building.
While these primary Mount Vernon souces refer to Washington's Dung Repository, a drawing of a stercorary was found during historical research. Richard Peters, a friend and correspondent of George Washington's, published his detailed description of a stercorary in 1808. This description is not of any actual structure and, instead, it appears to be based largely on another description taken from a British publication. At any rate, it is remarkably similar to archaeological evidence for Mount Vernon’s dung repository, including its overall dimension of 30 x 15 feet. The repository described by Peters is open on all sides, with only a shingled roof supported by posts set on a continuous brick foundation. Although the archaeological evidence indicates that the Mount Vernon stercorary was supported by posts set into the ground along the southern wall we think it was also open-sided.
Documentary research has not found an earlier stercorary or structure for making fertilizer in America or Western Europe. Whether the idea to build a Repository for Dung was Washington’s or based on something he saw or read about is not known. Prior to the construction of the building, horse manure was simply aged in a pile near the stable until it was seasoned enough to be placed on crops. By building a covered pit, lined with cobblestones, Washington created a spot where manure could age and be mixed with other organic material creating a true fertilizer.
In June 1796, Washington wrote directions for using the Dung Repository,
let others rake, and scrape up all the trash,
of every sort and kind about the houses, and
in the holes and corners, and throw it (all I
mean that will make dung) into the Stercorary.
Washington's directive to throw trash "of every sort and kind" from around the homelot into the Dung Repository corresponds well with the advice of John Spurrier, writing in The Practical Farmer (1793). As part of an extended discussion of soil fertility and methods to improve soil quality, Spurrier recommends a variety of waste and refuse to mix with animal manure to produce fertilizer. Interestingly, George Washington is listed as a subscriber to Spurrier's publication, and placed the largest order for books as well.
Spurrier's list of materials that he recommends for "making dung" includes, “rich earth, ant-hills, scrapings of roads, sweepings of filth round the buildings, leaves of trees, corn-stalks, thistles and coarse weeds, and all other articles that can be converted to manure.” To the above list, Spurrier appends "human urine and soap suds," wood ashes, sea sand, saw dust, "Tanner's Bark," dead animals, and "Woolen rags, cuttings of leather, particularly the refuse of skinner's and tanner's yards, with hair, (and) bones ground or powdered," as "very good manures."
Based on a letter Washington wrote in 1796, the Dung Repository was still in operation that summer. Documentary sources do not tell when it was torn down, but the archaeological excavation recovered artifacts from 1820 within the fill of the manure pit. A structure is depicted in approximately the same location on several mid-19th-century maps. The earliest of these is the Gillingham plan of 1855, which shows a building at that site labeled as the "Corn House, new.”
Two bird's-eye views, by Whateley and Sinclair and by Kern, depict a structure in the same location, opposite the stable. In both views open sheds are shown running the length of the north and south walls. In the more detailed Whateley and Sinclair view a wagon is stored inside one of the sheds, and the building appears to be framed of horizontal timbers between vertical corner posts. The timbers give the impression of having spaces between them, suggesting that this is a provision for ventilation related to the function as corn crib. Finally, a post and plank fence runs parallel to the building's south and east sides. Archaeological evidence suggests that the Dung Repository was torn down, possibly to make way for the corn house at the time of its construction, or at an as yet undetermined earlier date.
The research, archaeological excavation and artifacts provided important clues about the appearance and use of the building and it was reconstructed in 2001. Today it is an important reminder that Mount Vernon was not only Washington’s home, but a working farm where he carried out agricultural experiments.