On 11 Oct, 22:50, Phisherman wrote:
On Sat, 11 Oct 2008 04:08:26 -0700 (PDT), Nick
wrote:



Apologies for what may be a dumb and trivial question and I'm not sure
if this is the best group to query, but I'm wondering what a
particular soil moisture content actually means and how to achieve it
under controlled conditions. For example, if I have 100ml of a given
type of soil that's been dried and compacted so that there's
relatively few air pockets, after adding 100ml of water and letting it
permeate, would this mean that the soil now has a 50% water content
assuming no evaporation as taken place? Or would that be 100% moisture
as the total volume of soil has had an equivalent volume of water
added, or neither? * Further more, given my 100ml of soil that is
dried but perhaps isn't compacted and has some other non-soil
components, would adding my 100ml of water change the moisture content
then?

Input from anyone clued up on this most welcome!

Nick

Here's how it's done in the lab:

Weigh the empty container. *Add your sample. *Record the total,
calculate the weight of the sample. *Remove all the water from the
sample, weigh your sample again and calculate the water lost. *The
percentage of water content by weight is

(weight of water lost / total weight of the sample) * 100

The sensitivity has to do with the skill level of the scale user,
precison of the scale, and the sample size.

Soil is often sold by volume rather than weight. *But weights are used
when determining moisture content.

Bingo, many thanks for the pointer. Weighing should work perfectly,
and seems completely obvious now but not something I'd considered.
It'll be interesting to take some soil samples to analyse, and also to
get an idea of how much watering is required and how often. For turf
areas we've laid RTF, which seems an exciting product (and hopefully
lives up to the promise of self-healing as patches are being killed
off by foxes!), and use MP rotators to give even watering, but as with
other areas, how long to irrigate and how often is really an unknown
at the moment.