Tag Archives: agriculture

De Compostus: A Brief History of Putting Animal Poop on Plants

A relief of a Gallic-Roman harvesting machine.

A relief of a Gallic-Roman harvesting machine. Credit: Public Domain

“When the weather is bad and no other work can be done, clear out manure for the compost heap,” recommends Roman statesman Marcus Porcious Cato, better known as Cato the Elder. In his writings De Agricultura, he shares the secrets to running a successful farm-business in the ancient Roman Empire.

In this work, Cato, who lived between 234 and 149 B.C., provides us with an early how-to guide for enriching the soil through the practice of composting.

The Dirt on Dirt (and Compost)

Compost is not actually soil itself, but the dark, crumbly result of a controlled process of breaking down animal and vegetable matter. The resulting product is fairly stable, no longer decomposing at the previously speedy rate, and is full of nutrients (especially nitrogen and carbon) and minerals in forms ready for hungry plants to absorb.

Black gold: The earthy results of composting with worms.

Black gold: The earthy results of composting with worms. Credit: Red58bill, Creative Commons Attribution 3.0 Unported license.

But composting isn’t just any old rot, full of stink and muck. It involves humans maintaining roughly the right ratio of moisture, air, carbon, and nitrogen. It involves aerobic decomposition, which requires oxygen and is the main reason for occasionally “turning” or mixing a compost pile. It also involves microbes, fungi, insects, and worms all munching on and pooping out the delicious organic (carbon-based) goodness in a compost pile.

Composting for the Lazy and the Ancient Scots

A dedicated “compost pile” isn’t even necessary for this magic to happen. One of the many ways to compost is referred to as “sheet composting.” At the end of the growing season, you mix up a moist layer cake of nitrogen-heavy “green” materials (e.g., mowed grass, bolted lettuce plants, chicken manure) with carbon-heavy “brown” materials (e.g., chopped up woody plants, dead leaves, cardboard). You toss all of this right on top of a garden bed, cover it with some burlap sacks, and ignore it until spring, when you will find several inches of nutritious compost on top of the plot.

This method doesn’t sound all that different from some of the oldest practices of humans composting. Sometime in the Neolithic Age, roughly 7,000 years ago, when hunter-gatherers began making the switch to farming, they figured out that having manure and vegetable waste in the soil around their food plants was a great idea.

A 2005 British study published in the journal World Archaeology found evidence of farmers in what is now Scotland using their garbage piles of food scraps and manure (“midden heaps”) as garden beds:

“from the Neolithic to the Iron Age, midden heaps were sometimes ploughed in situ; this means that, rather than spreading midden material onto the fields, the early farmers simply ran an ard over their compost heaps and sowed the resulting plots.”

In addition to the Romans and Neolithic Scots, the ancient Chinese and Egyptians also had an appreciation for amending the soil.

When in Rome, Compost as the Romans Do

Cato the Elder, however, preferred burying manure and other compostable materials around the roots of olive trees and grape vines and letting it break down there.

“See that you have a large dunghill; save the manure carefully, and when you carry it out, clean it of foreign matter and break it up. Autumn is the time to haul it out. During the autumn also dig trenches around the olive trees and manure them.”

“In an old vineyard sow clover if the soil is lean (do not sow anything that will form a head), and around the roots apply manure, straw, grape dregs, or anything of the sort, to make it stronger.”

His techniques apparently went beyond these modern sustainable farming practices and strayed into what we might now call the “biodynamic” (“a spiritual-ethical-ecological approach” to farming that emphasizes the land as an interconnected, living organism and takes into account things like planting and fertilizing based on lunar cycles and burying in the soil at night a cow horn stuffed with cow dung).

Perhaps Rudolf Steiner, founder of the biodynamic farming movement, took his inspiration from Cato the Elder and his composting contemporaries in Rome:

“Divide your manure as follows … Save the last fourth for the meadows, and when most needed, as the west wind is blowing, haul it in the dark of the moon.”

Farmers, take note: a new moon is the best time to compost.

Not All Animal Poop Is for Plants

Cato gives excellent advice for improving the soil with a variety of manure sources, as well as a sort of olive oil-based “dressing” (amurca) to give crop trees a boost:

“Fertilizers for crops: Spread pigeon dung on meadow, garden, and field crops. Save carefully goat, sheep, cattle, and all other dung. Spread or pour amurca around trees, an amphora to the larger, an urn to the smaller, diluted with half its volume of water, after running a shallow trench around them.”

Pigeon, goat, sheep, cattle … all are good sources of manure for Ye Olde Compost Pile. But a question that often comes up for Ye Modern Urban Composter and Pet Owner is whether or not you should add dog or cat poop to your compost.

In short, no.

In long, because dog and cat feces are full of pathogens, or disease-causing microbes and parasites which humans should want nothing to do with. Many of these pathogens or their eggs or spores won’t be killed by the composting process and can stick around in the soil for a long time, in some cases, up to four years.

Dog poop in particular has been studied as a plentiful source of nasty microbes, being called a “reservoir,” even, for Escherichia coli (E. coli). Rural communities in Canada have been observed to have a high incidence of pathogens in dog feces, including Toxocara canis (roundworms), Echniococcus granulosus, Giardia duodenalis, Cryptosporidium spp., and Campylobacter spp. And let’s not forget Salmonella.

What do these pathogens do to people? All kinds of fun!

  • Diarrhea!
  • Cramping!
  • Nausea!
  • Skin sores!
  • Inflamed stomach lining/heart wall/lungs/kidneys!
  • And more!
Some like it hot: A compost pile with cow dung reaches 145 degrees Fahrenheit.

Some like it hot: A compost pile with cow dung reaches 145 degrees Fahrenheit. Credit: Fishermansdaughter, Creative Commons Attribution 2.0 Generic License

These are not the sorts of things you want to be putting on your tomatoes and lettuce.

Of course, livestock manure can have some pathogens too, such as E. coli and Salmonella. To kill these pathogens, the manure needs to be in a “hot” compost pile, where they are exposed to temperatures maintained at 140 degrees Fahrenheit for at least three days. It’s generally accepted that composting dog and cat feces would run a much greater risk to humans. So, don’t do it.

Instead, “doo” as the Romans do.

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