Moisture Content of Soils

The conventional oven method is a 'golden standard'. In addition there are (among others):

Electrical resistance

Neutron absorbtion

IR reflection.

Each method's success depends on lots of variables and any method should be well calibrated before using it's results. If you Google and Wiki these methods you'll have an idea about their applicability in your particular case.

In agriculture (probably the most widespread use of this type of measurement) electrical resistance calibrated for local condition is the preferred method.

Do you mean: you've got the data, and don't know what to do with it:-

In which case try Excel.

Or, are you looking for possible field solutions:-

in which case dovy's answer looks good.

We must know which field test method you are using.

If you are using a nuclear density gage that is equipped with an offset function, you can program it to compute the moisture content based on the results of your oven drying tests. If not you can hand calc, i.e. add or subtract the difference between the field test and the lab test. Even if the relationship is not linear, as long as you are testing soils in the same moisture range (+/_ 2%), the accuracy should not be too bad. Say 0.2 or 0.3 percent. That should be sufficient for determining in place density of the soil; if that's what you're doing, which is something else you should let us know.

One field test method dovy left out was the "Speedy Moisture Test." This test uses a reagent (calcium carbide) that reacts with the moisture in the soil to produce a gas (acetylene) causing a pressure increase in the test vessel. The indicated pressure is then compared to a chart for the soil type you are testing to obtain the moisture content. This test has good repeatability and compares well with oven drying for moist soil types.

Let us in on the field test method, and why you are testing plastic material, and we will try to help you out.

the field method is the use of the speedy meter

The Speedy meter i'm using is quite old. It was purchased about 3 years ago but had never been used. Could this be the problem? Also, is there a specified amount of calcium carbide i was supposed to use?

The complete unit should have a scoop for measuring the calcium carbide. Two scoops is typical, but this measurement is not critical, you just need to make sure you have enough reagent available in the vessel to react with ALL the water.

Here is a link to the procedure we use in Florida: FM 5-507

I would definitely calibrate the unit after being idle for 3 yrs.

Hope this helps

Thanks so much PMoon, you have been so helpful.

PMoon, please one more thing; can you tell me the principle behind the speedy tester?

You are a life saver! Thanks so much...

Serendipity?

http://www.decagon.com/micro/fresh/?utm_campaign=fresh&utm_source=globalspec&utm_medium=email