Dirt vs. soil, disease vs. disorder

OK, let's get some things clear, by definition if necessary. So a lot of plant experiments, especially those done in glass houses in pots require a growth medium for the plants. While mixing up a batch for some 240 pots, a security person on rounds came by and said, "So are you mixing up some dirt?"  Our stock answer followed, "No, dirt is something you find under your finger nails and in certain types of books and movies."  "We're mixing up some soil." This does mean that mixing soil can result in dirt under your finger nails. Similarly and widely misused are the terms disease and disorder. A disease is an illness that has a causative organism, a disease organism. A disorder is has a genetic or nutritional basis, but no causative organism is involved. Unfortunately the two terms are thrown around willy-nilly and used as basically interchangeable. So let's be a little more precise out there, people.

Fun galore!

Today we'll have some fun!  If you have some free time, stop by and join the fun!  It's harvest season and it's how we get our data.  Last week the above ground portions of this experiment were harvested, but now it's the below ground portion that gets harvested.  Now here's the thing about roots; they branch and branch again and again and again.  And they really hang on to soil, intimately intertwined you might say.  Extracting roots from soil is never easy especially when you want to save the soil and use it for phase two.  A student is also harvesting their experiment and is washing the soil away from the roots, which while a tough job, is much easier than what we are going to try.  This is the sort of thing that makes you want to be a tube-sucking gel jockey.  It's soil, not dirt.  Dirt is something that you find under your finger nails and in certain types of books and movies, but somehow in the process of doing this, soil becomes dirt.  TPP hopes he can find his apron. 

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.

Green side up

Language is a funny thing, especially English as it is a linguistic conglomerate which makes for lots of potential fun. And for botanists and horticulturalists, nothing is more fun that when someone tries to make sense out of soil versus dirt.

Here I will pass along neither dictionary nor professorial opinion, but the New England yankee wisdom dispensed by my Father, the gardener. If anyone referred to the material in his garden as dirt, he'd reply, "It's soil." "Dirt is something you find under your finger nails and in certain kinds of books and movies." No one ever has been accused of using soily language, so this distinction always made a certain sense to me.

Of course as a biologist I know that soil is a complex substance, part inorganic and part organic. A cubic centimeter of soil, a volume about the size of a sugar cube for those of you somewhat metrically challenged, could harbor some 8-20 million organisms. Even the smell of soil, that earthy odor, comes from the metabolic activities of certain bacteria.

So something might start out as dirt, but if composted correctly, it can become soil. And in this I note that for years I have used two layers of newspaper covered with straw to mulch my kitchen garden. Although the data is not publishable, I'm quite certain that the opinion pages of our local newspaper compost the most quickly and thoroughly.