Sheep Manure and Rye Agriculture in Portugal

For all those of you who are interested in identifying the archaeology of past agriculture, you might take a look at the Spring/Summer 2008 issue of the Journal of Ethnobiology.

Sheep on a Portuguese Farm. Photo by John Barreiros

In an article called "The significance of sheep in the traditional agriculture of Beira Alta, Portugal", George F. Estabrook describes how traditional rye farmers kept a few sheep, even if they produced very few lambs, didn't produce much milk, produced low quality wool and were not eaten. Turns out, the farmers used sheep, um, excrement to mix with a nitrogen fixer called "giesta" to use as fertilizer, and so have been regularly replacing the nitrogen sucked out of the soil by centuries of rye grain.

Also, for you stable isotope types, adding manure to soil lowers the carbon/nitrogen ratio of giesta from its natural 30 to near 20. Nice bit of ancient chemistry here.

Estabrook, George F. 2008 The significance of sheep in the traditonal agriculture of Beira Alta, Portugal. Journal of Ethnobiology 28(1):55-68.

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