This is the second in a series of blogs, about ancient soil amendments used in the garden. Each blog will discuss a common and specific type of soil amendment used in the garden, along with documentation for its use, as well as occasionally discussing why a particular soil amendment was chosen, or its relation to modern gardening practices. The original blogs, along with other gardening related blogs, can be found here.
Manure is talked about quite frequently in husbandry and gardening texts of the period. Manure is unique in that it is both a substance you add to the soil as well as a practice you regularly complete. In the modern mind, manure is is synonymous with animal waste. This is not true in medieval texts. Sometimes manure means animal waste, other times it means anything biodegradable.
Medieval authors compare the dung of different animals as well. Cato outlines specifically that you can just spread pigeon dung on your fields, but you should store piles of other animal waste. Geoponika also discusses the benefits that come from different animal wastes. Walter of Henley warns his readers that manure alone will only benefit your soil for two or three years.
Although the practice is documented as post-medieval, the use of manure to heat winter cold frames is one that could easily have been used. There was a Victorian practice where a brick or stone box was combined with fresh, hot manure, giving several weeks of early heat to plants. Eve Otmar of The Colonial Williamsburg Foundation told me you would get about 4-6 weeks extra heat using this method.