What does 50% soil moisture content actually mean?
 

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

What does 50% soil moisture content actually mean?
 

In article
,
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

Perhaps of interest.

http://www.ext.colostate.edu/drought/soilmoist.html

Bill

--
Garden in shade zone 5 S Jersey USA

Fight TB http://xdrtb.org/

What does 50% soil moisture content actually mean?
 

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

http://en.wikipedia.org/wiki/Soil_moisture

What does 50% soil moisture content actually mean?
 

On Oct 11, 7:08*am, 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

Who usually does your homework?

What does 50% soil moisture content actually mean?
 

Who usually does your homework?

LOL, who's being a tad cheeky then, and I see that you didn't feel
confident to give an answer yourself :) My last pre-uni homework was a
couple of decades ago, but I agree that it does sound like a homeworky
type thing. I had looked at WP earlier, but thanks to Dave for the
other link.

I was actually wondering in relation to the irrigation aspect of a
computer controlled landscape project that I'm working on covering
irrigation, lighting, audio etc. Our irrigation controllers coupled
with techline and other devices should keep the watering nicely under
control, and the plan is to have watering schedules adjusted
automatically by the controller in part from predictive weather
forecasts from sources such as the Beeb. However I was also thinking
about getting feedback from the soil about how things are going by
adding some RF moisture sensors to remotely monitor irrigation
effectiveness and to factor that into the schedules. I knocked
together a simple proof of concept moisture sensor last night using
the most basic tried and tested method (AC resistance) and that seems
to work very well with no drift due to ionisation, but it had me
thinking about testing and calibrating. That said, due to the
limitations of the resistance technique I'm expecting to make the
sensors auto-calibrate themselves to sufficient resolution in the
field so to speak as any attempt at pre-calibration may be useless,
but I was still curious about what adding a given amount of water
actually means in terms of moisture content.

What does 50% soil moisture content actually mean?
 

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.

What does 50% soil moisture content actually mean?
 

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.