Soil Moisture Content

I've been collecting soil temperatures once a week at a randomly selected spot in my back yard for just over two years, some days the soil turns to mud as soon as I step on it and during the summer regular watering is needed to stop it turning into dust.  I became curious to know how the water content varied over the year.

The methodology is very simple.  Around sunset on most Sunday afternoons, I take an empty and washed dog food tin which has been weighed and half fill it with earth after which it is weighed again.  This being winter, we heat one room with a coal fire, this burns down overnight, by morning there is a pile of hot ash in the grate.  These ashes are piled up around the tin and by evening, the soil is dry and crumbles into dust when rubbed between the fingers.  The final step before the soil is returned to the garden is to weigh it a third time.  When spring arrives, I will simply leave the tin in a warm place until it's weight stabilises.

The weather during January can best be described as winter, at the beginning of the month it was wet winter and at the end of the month it has been cold winter (relative to places like Scotland and New York, winter in the south of England is just mild).  During this time, the moisture content from the sample area has remained constant at around 25%.

At present, I have no idea what the range of values should be.  The garden is a series of terraces on a slope, the sample is taken at the top where the drainage is good.  The lowest terrace often becomes water logged so there is clearly some significant variation over a small area.