If you remember, we discussed last week the multiple diagnostic surface epipedons found in the soil’s A horizons. One of the five epipedons was anthropic, which is soil effected by significant human impact. While most people would associate this with farming and tilling of the land, as well as the overuse of heavy machinery or perhaps the use of pesticides or manmade fertilizers, my thoughts immediately stray to literal human impact, cemeteries, and the decomposition of human cadavers. (I know that may sound a little gross. I swear I’m not always so morbid.) So I decided to do a little research to find out more how human decomposition effects the earth’s soil.
An article in Environmental Geology reviewing the human decomposition processes in soil cites that while researching such a topic, one must also obviously consider the natural environmental factors and soil structures of the land before being used for human burial. The article also recognizes the effects of “cemetery management, exhumations, forensic investigations and anthropology” on the soil. Regulations that vary under the discretion of the cemetary management may include the use of fertilizers, the types of monuments erected, and whether family members and mourners may plant live flowers or greens at the site. The bodies themselves do also greatly effect the contents of the soil.
Once in the soil, a human body becomes subject to the aerobic (initial) and anaerobic (longterm) environmental conditions including weathering and erosion and soil evolution. The major human components released during decomposition include protein, carbohydrates, fat and bone. Carbohydrates release large quantities of carbon, hydrogen and oxygen, while the proteins include those elements as well as nitrogen, sulfer and some traces of iron.
You may wonder how these elements would saturate the soil if bodies are most commonly entombed within a casket when buried. Keep in mind that most caskets deteriorate due to water saturation and pressure of the soil within approximately ten years after burial. The existence of “percolating groundwater” and microorganisms then further increase the rate of decomposition and spread of minerals throughout the surrounding environment. This process normally takes place within six feet of the surface of the ground, therefore still allowing the impact to be considered anthropic.
The Merriam-Webster Dictionary defines the term anthropic to account for anything “of or relating to human beings or the period of their existence on earth.” So I suppose that while the existence of human remains in the soil may not be an initial consideration of most soil researchers, human burial rituals do impact the biology of the earth.