I began using the "buried cloth" method in my teaching practice with organic farming students in about 2010.  I found a reference to it as a method to assess soil health in a UK publication from 1988.  See the "history of buried cloth" presentation on this website.

As a soil health method it is easy and often shows large differences due to various soil conditions and farming practices.  The buried cloth, once rinsed, is often quite interesting to look at, with the pigment left by the microbes adding various intensities of color, depending on the time of year, etc.  For most samples, the heavy cotton canvas, used by artists, and available in most fabric stores was used.

The "soil calendar" page attached, shows what happens when the cloth is buried at different times of the year.  

I experimented with this method, and also natural dyes from plants, paint from soil, felt, making paper from apple pulp and weeds; etc, and included a summary of the these methods in contemporary and historic art discourse.  That thesis is also attached for those that are interested in more detail.

And finally, I used all of these methods when teaching organic farming, and did an in-class assessment/survey to see if 1) the students are learning from them, and 2) do the students enjoy using these methods in addition to traditional teaching.  I also surveyed students who learned these same methods as part of an art class.  Those results were summarized in a teaching methods poster for a conference, and are also attached to this webpage.