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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 |
#2
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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/ |
#3
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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 |
#4
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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? |
#5
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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. |
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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. |
#7
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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. |
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