Filthy dirt

Experimental work with plants takes some planning and some time.  Nothing magic about plant growth so you just have to wait, but time to get a glasshouse experiment going.  And so an energetic student ready to get underway with the next experiment asks, "Where do I find the dirt?"  Thus they innocently gave voice to a common misconception.  TPP answers, "You find dirt under your finger nails, and in certain kinds of books, movies, and websites."  "Perhaps you mean soil?"  Soil and dirt are not the same at all.  "Does that mean my research proposal has to be changed?"  "Yes."  Careful consideration has to be given to the soil used for experiments.  Sometimes you can use a commercial potting mix, or just make one, but a potting mix is not at all like the soil these plants naturally grow in.  Soil is more than just a whole bunch of eensie weensie rock particles and organic matter, it also contains microorganisms to the tune of about 8-10 million per cubic centimeter (for the non-metric, a volume about the size of a sugar cube).  Not only that, but the plants growing in a particular area can greatly alter the soil microflora to their benefit and perhaps the detriment of others, and in particular that includes invasive plants.  This produces some problems in the experimental design, but let's let that go for now.  Fortunately your mentors were thinking way ahead and soil (sod actually) was dug 2 months ago and set aside in anticipation of this experiment; soil from our research prairie, soil affected by an invasive plant, and soil from an adjacent grassy meadow, so a very practical consideration is next.  Those buckets with great big old chunks of sod need to be screened to remove rocks and root systems and in the process reducing the big old chunks into a much finer texture.  It's a great student activity for a cold winter afternoon.  So, no dirty thoughts, just become one with the soil.  Wonder how many hits this title will generate of people looking for real "dirt"?  We'll see if the data for click ins and outs, i.e., zero time spent reading the blog goes up.  Something like this happened a week ago when the daily traffic at TPP jumped up by a factor of 3 for no particular apparent reason producing quite a blip in the data.