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Re: EM50G Logger- Iphone app?

Virgil — Fri, 11 May 2012 11:41:49 -0700

Check out our new web app!

http://www.ech2odata.com/viewer/login/

You can view your last week's worth of data in a chart view and download all data in an .xls format. You can pull it up in Safari on your iphone. All of your subscribed EM50G's are available when you have entered your user information. You can either create a new user and subscribe to your EM50G's through the web app or you can enter your user information from Datatrac 3 (this info can be found under setup/user configuration).

Please leave feedback on features you like or features you would like to see...

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EM50G Logger- Iphone app?

tamz — Thu, 10 May 2012 21:14:15 -0700

Hello there,

I recently started using this EM50G logger with DataTrac software. Is there an iphone app for datatrac to view the reports on phone?
Does anybody have any information regarding this. please share...Thank you.

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Re: ECTM and 5TM outputs

ChinaBuck — Tue, 08 May 2012 15:59:36 -0700

On the subject of calibrating soil moisture sensors. 1) I have never been able to convince myself that my lab calibrations were valid for field use (i.e. within plus/minus 2 vol percent. 2) Field attempts at calibration have done little better. Based on these frustrating results I concluded that soil is not a good media to work with because it is plastic, swelling, shrinking, electrically variable and non-constant material. So I calibrate under as close to the field conditions where the data will be used, and suffer the criticisms as they arise.
I hope that this note does not trivialize the problem in the least, it is just the frustration of working with materials like soil.

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Re: Calibrating a soil - bulk density problems

Virgil — Mon, 07 May 2012 16:33:31 -0700

The more consistently you can run your calibration, the more accurate your data will be. That being said, you have some leeway in how close you have to be to the "true" bulk density. You need to see a 16% difference in bulk density before you will observe a 1% change in volumetric water content (Decagon internal research). The ~ 5.5 percent difference that you see in this data point shouldn't have a large impact on your calibration. It may be worth trying the point again, particularly if you are still at a low water content, but if the R^2 for your curve fit is still 0.95 to 0.99 you should be in good shape. Look at that point in relation to your curve as well. If it looks like it may have a lot of leverage and is pulling your curve down it is probably a good idea to run it again.

A sandy soil can be particularly difficult to pack back to your target bulk density as you near saturation. At a certain point that may be as good as can be done.

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Calibrating a soil - bulk density problems

Usu — Mon, 07 May 2012 02:01:43 -0700

Hi! I'm trying to learn how to make a good calibration on an "usual soil" with 10HS and EC-5 probes. I've got infinite questions but I start with the most important. Each calibration point has to be characterized by the same bulk density that the soil has got in field. Of course it's impossible to recreate the same density at each point of the calibration, particularly when the soil starts to be very wet. How is the maximum difference between the recorded and the desired density that can I accept? For example: if I'm working with a sandy soil with a field density of 1.45 t/m3 and, during one point of the calibration, I obtain a density of 1.375 t/m3, can I use this point to build up the curve or have I to eliminate it? Thank you a lot - Alberto

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Re: 10HS sensor distance from soil surface

TurfHead — Fri, 04 May 2012 09:42:03 -0700

Thanks for your answer,
I installed my sensors on an horizontal plane at a depth of 10 cm, so everything should be fine.

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Re: 10HS sensor distance from soil surface

Virgil — Thu, 03 May 2012 16:39:26 -0700

Please check out this document (http://www.decagon.com/assets/Uploads/10HS-Volume-of-Sensitivity.pdf) for the definitive discourse on the volume of sensitivity of the 10HS. The short answer is that 5cm of soil in every direction from the probe is sufficient, but cutting it pretty close. We recommend that you install the sensor 10 cm down to be certain that it is sufficiently contained within the soil.

As long as the sensor is buried all the way up to the cable your sensor will be fine installed in the vertical plane. If you are installing your sensor horizontally, you must have it buried at least 5 cm from the surface. Bear in mind that getting air incorporated into your reading is one of the worst biases that you can have for the quality of your data.

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Re: EC-TM suddenly stopped working.. No data from serial

Virgil — Thu, 03 May 2012 16:32:51 -0700

Hmmmn,

I do not think that the heat can corrupt the data, but warming and cooling can expand (or contract) solder joints in the sensor or in the connector. There are 2 joints in the sensor that can be susceptible to this, and as they age in the field this can develop. The stereo connector is one solder joint that can develop this over time, particularly if the cable is frequently bent or twisted near the connector that solder joint can be broken. If you have bare leads rather than a stereo connector disregard this part.

The neck of the probe where the cable joins it is another susceptible point. One way to test if this may be the case is to set your sensors up to read continuously, then move the cable around near these joints. If the reading changes or jumps or goes to NA, then the problem is likely this joint.

Can you visibly inspect the probe or is it completely buried? The condition of the overmold is another variable of interest.

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10HS sensor distance from soil surface

TurfHead — Wed, 02 May 2012 18:12:14 -0700

I am confused about the distance that I should keep between the 10HS sensor and the soil surface. The 10HS manual (page 6) says that "sensors should not be installed within 5 cm of the soil surface", but the application note available on the website says that "Decagon recommends that the 10HS not be installed within 10 cm of the soil surface or any foreign object in the soil".

So what is the recommended distance between the sensor and the soil surface: 5 cm or 10 cm?

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Re: EC-TM suddenly stopped working.. No data from serial

aksonlyaks — Wed, 02 May 2012 00:26:26 -0700

Hello Virgil,

Actually, the sensor which was not working suddenly started first sending all garbage but around 15 bytes of string and than later on started working. But in between sometimes it gives garbage values. I dont understand how suddenly it's working.
Also, i double checked the connecting wire which was fine. I'm using independent reader only to read data from sensor.
I'm using my sensor in open where temperature at day time reaches to about 41 degree Celsius. Wires are not covered with anything. So do you think because of heat data may be getting corrupted? Also, if sensor can withstand 40 to 60 degree celsius?

regards

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Re: Unknown sensor convert to a 5TE

Virgil — Wed, 25 Apr 2012 12:13:17 -0700

Hello,

Sorry that it has taken so long for me to reply to this post. We had some technical problems with our forum website that we have now sorted out.

I do not think that we will be able to convert the data. Many of our sensors are analog sensors that only output a voltage. This will not have any meaning to the 5TE. If the logger has just recorded the serial string, then it should be relatively easy to convert it to 5TE output. Please email your data to support@decagon.com if you would like us to check it out and see if there is anything we can do.

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Re: EC-TM suddenly stopped working.. No data from serial

Virgil — Wed, 25 Apr 2012 11:59:49 -0700

Hello,

Sorry that it has taken me so long to respond to your message, we have had some technical difficulties with our forums that we are just now sorting out.

If you are not getting a serial string upon exciting the sensor, then the sensor may have failed. Please double check your cables to make certain that they have not been damaged by rodents or human activities such as harvesting or mowing.

What type of datalogger are you reading it from? It is good to test sensors on an independent reader if possible to rule out datalogger problems.

Unfortunately, the EC-TM has been discontinued for a couple of years so your sensor is out of its one-year warranty. Please contact support@decagon.com, or your local distributor (http://www.decagon.com/where-to-buy/) for specific support regarding sensor replacements.

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Unknown sensor convert to a 5TE

ingjorge — Mon, 09 Apr 2012 05:27:40 -0700

Dear I have a problem, I not specified the sensor type in the datalogger and downloaded it. I need convert this value in value the 5TE. it is posible?

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EC-TM suddenly stopped working.. No data from serial

aksonlyaks — Fri, 06 Apr 2012 08:29:07 -0700

Hello to all,

I have EC-TM which suddenly stopped responding after working for few days. When i checked the output it's sending:
<0><0>øþ and nothing else.
I dont know what happened to it suddenly.
I used to provide 5v as excitation. The excitation circuit is self made and used iris mote and mda300. Excitation is taken from the excitaion generated by mda300.
Can anyone tell me what's wrong here. Please need help badly.

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Re: Sensor Calibration

topinstruments — Fri, 30 Mar 2012 22:58:23 -0700

There is no need to that...

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Leaf Porometer Upgrade

Virgil — Tue, 27 Mar 2012 07:28:22 -0700

Please feel free to post questions about the leaf porometer sensor head here. If you have specific questions about your particular porometer or wish to speak with a customer service representative, please contact support@decagon.com.

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Re: Temperature and measured permittivities (5TE)

Aeniden — Tue, 27 Mar 2012 06:07:49 -0700

Thank you fot this quick answer, now I understand what are the real factors of the dielectric measures.

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Re: Temperature and measured permittivities (5TE)

Virgil — Mon, 26 Mar 2012 16:00:18 -0700

The relationship between dielectric permittivity and temperature is kind of tricky for soils. The dielectric permittivity decreases for water as the temperature increases, so at higher water contents this trend would dominate. Every soil will have a unique relationship though, and a different sensitivity to changes in temperature. We usually recommend a multivariate approach post-analysis to correct for temperature (http://www.decagon.com/education/correcting-temperature-sensitivity-of-ech2o-soil-moisture-sensors-13394-02-an/) variation in water content. We do not understand the phenomenon well enough to implement a mechanistic approach (yet).

I hope this helps...

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Temperature and measured permittivities (5TE)

Aeniden — Mon, 26 Mar 2012 04:09:26 -0700

Hello everybody,
I'm a student and currently working with the 5TE probes for my course. I've worked on the bulk density, water volumic content and temperature effects on the measures of permittivity. The experimentations about the effect of temperature have lead me to make a graphic :

The problem is that when the temperature increases, the dielectric permittivity décreases for a WVC of 0.40 m3.m-3, but increseases for lower VWC. Could you give me some infos concerning the phenomenon? Is there a VWC for what the temperature doesn't affect the permittivity?

PS: The bulk density of the sample is 1.6, "Epsilon" is the dielectric permittivity that is measured by the 5TE probes.
PS2 : The leading coefficients of the curves decrease with the increasing of the VWC.

PS3 : Sorry for my bad english skills, I stay connected if you have questions

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Re: Soil bulk density and sensor calibration

ColinSC — Thu, 15 Mar 2012 16:57:05 -0700

Hi Abri,

You ask a good question. On the surface, it would appear that collecting a bulk density sample would not be that important. You will measure that during your lab calibration anyway. However, the reason you would want to collect a bulk density sample in the field is to make sure that your lab calibration bulk density matches that of your field soil. One of the common mistakes people make when doing lab calibration is that they fail to match the field bulk density, usually because they over pack their soil, especially as they go to higher volumetric water contents. We have seen through our experience with calibrations that, as the bulk density of a soil decreases, it increases the y-intercept of the calibration curve, where linear calibration lines would be parallel and the lower bulk density soils shows a higher VWC at the same sensor output. Thus, if the soil calibration over-packs the soil, you may underestimate the actual VWC of your soil.

I hope that helps.

Colin

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Soil bulk density and sensor calibration

abri — Thu, 15 Mar 2012 06:35:20 -0700

Hi there,

I'm a newbie to the world of soil moisture sensor calibration. I have read up a bit but I am still unsure why one has to collect a bulk density sample in the field when you collect your soil for the lab tests? I mean, you will wet it to different degrees during the calibration procedure and take a bulk density sample at each wetness stage anyway.

Could someone please explain this to me?

Thanks in anticipation
Abri

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Re: Lysimeter maintenance

LeoR — Wed, 14 Mar 2012 16:52:09 -0700

Depending on the type of instrumentation you put into the lysimeter, you can expect it to be atleast 3 to 5 years before there is any maintenance required that is going to be labor intensive. The load cells should last a very long time, especially if precautions are taken to prevent the load cells from being overloaded.

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Re: Lysimeter for shrink/swell soils

LeoR — Wed, 14 Mar 2012 16:51:43 -0700

Shrink-swell soils are a hard soil to make any type of measurements in because of all of the challenges they present. The key is to not create any preferential flow paths artificially by putting walls up that the soil can shrink away from. A good type of lysimeter for shrink-swell soils is a controlled tension lysimeter with only a suction plate at the bottom. You will get accurate measurements of flux rates without introducing any preferential flow paths. Any type of lysimeter that uses walls to encapsulate the soil is probably not going to be optimal for soils with a high shrink-swell capacity.

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Re: Measurements to make before installing a weighing lysimeter

LeoR — Wed, 14 Mar 2012 16:51:13 -0700

It is important that you have characterized the soil that you want to install a weighing lysimeter. You want to make sure that it is representative of the site that you are trying to understand. It is also important to make sure that there is not a chance that the soil has a seasonal water table that could flood the lysimeter and its service well damaging equipment.

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Re: Can lysimeters be moved site to site?

LeoR — Wed, 14 Mar 2012 16:50:48 -0700

In most cases you will not be able to reuse a lysimeter system. It would take a significant amount of work to remove it without damaging the equipment. Lysimeters are a more permanent installation.

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Re: Install lysimeter without disturbing soil

LeoR — Wed, 14 Mar 2012 16:50:14 -0700

It is hard to install a lysimeter in a site without disturbing the surrounding soil because of the wells that need to be installed. You can take intact monoliths that are undisturbed and UMS has been doing this for over 20 years in a broad range of different soil types. They know what it takes to get a good intact monolith. In special circumstances it is possible to install a lysimeter system with minimal disturbance to the surrounding area. An example of this is a lysimeter site that UMS had to install in a national forest in Germany in which they could only disturb the soil that the lysimeter wells were sitting in without extending into the surrounding area. They were able to take special precautions to conduct this installation without disturbing the surrounding area.

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Re: Preferential flow

LeoR — Wed, 14 Mar 2012 16:49:45 -0700

If you are only trying to measure preferential flow in soil a pan lysimeter may be a good tool for this. Because you are trying to measure flow through cracks in soil, flow divergence is not as big of an issue.

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Re: Smallest UMS lysimeters?

LeoR — Wed, 14 Mar 2012 16:49:18 -0700

The smallest weighing lysimeter available from UMS is 30 cm in Diameter and 30 cm deep. They also have controlled tension lysimeters that use a 30 cm suction plate.

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Re: Obtaining an intact monolith

LeoR — Wed, 14 Mar 2012 16:48:46 -0700

We have a couple of tools that allow us to take intact monoliths with a large excavator. One uses four hydraulic cylinders to slowly push the shell for the monolith down into the soil. We use cold forged stainless steel ring because it has smoother sides reducing the amount for friction it applies to the soil to reduce compaction. There is also a large device that we use to guide the Lysimeter as we press it down with the excavator.

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Re: Repacked monolith

LeoR — Wed, 14 Mar 2012 16:47:33 -0700

It is nearly impossible to make a repacked lysimeter and get the correct soil structure unless you are dealing with structure-less soil. The best thing you can try and accomplish is returning the soil to its approximate original bulk density. Only time will allow the soil to return to its original structure. If it is crucial that the soil still have its original structure then a intact monolith is going to be needed.

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Re: Cost of weighing lysimeter

LeoR — Wed, 14 Mar 2012 16:47:06 -0700

The cost of lysimeters will vary depending on the number of lysimeter per station that are installed and how they are instrumented. The cost for a single lysimeter system will likely start around $30 to $40 thousand for a more basic system. New small-scale weighing lysimeters are a lower cost option that still allow you to get the same precision data as you would get with a larger lysimeter.

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Re: Spatial coverage of lysimeters

LeoR — Wed, 14 Mar 2012 16:46:29 -0700

Getting better spatial coverage to understand spatial variability is going to be very similar to a sampling scheme. You can either go with larger lysimeters that encompass more of the spatial variability or you can go with more lysimeter to get better spatial coverage. Small-scale weighing lysimeters make those more a feasible option for your budget.

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Re: Lysimeters in potatoes

LeoR — Wed, 14 Mar 2012 16:45:55 -0700

Because of the amount of disturbance required with potato farming a weighing lysimeter is probably not a very feasible option. A controlled tension lysimeter, static tension lysimeter, or pan lysimeter are going to be better options because all of the equipment is going to be below the disturbed area.

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Re: Improvements in tension controlled lysimeters

LeoR — Wed, 14 Mar 2012 16:45:29 -0700

New systems available for controlled tension lysimeter have become much more of a turn-key solution. They encompass everything built-in to control the tension based on tensiometer measurements and easy to use software to set the parameters to which the control needs to be

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Re: Lysimeters vs. Piezometers

LeoR — Wed, 14 Mar 2012 16:44:51 -0700

A piezometer is a device used to measure the piezometric head of groundwater at a specific point. A lysimeter is a tool used for measuring the vertical movement of water through the vadose zone in order to help understand evapotranspiration along with flux rates of contaminants.

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Re: Oxygen loss?

LeoR — Wed, 14 Mar 2012 16:42:57 -0700

The oxygen liberated from water in photosynthesis is to minor of a loss to consider.

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Re: Installation services

LeoR — Wed, 14 Mar 2012 16:42:02 -0700

We are now bringing the lysimeter systems from UMS here into the US which does include the design, installation, and training on how to maintain the lysimeters.

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Re: Suction cups vs. lysimeters

LeoR — Wed, 14 Mar 2012 16:41:31 -0700

Suction cups, although they are often referred to as suction lysimeters, are different from lysimeters because they are only capable of pulling soil water samples. The do not measure flux rates through the vadose zone. You can read more about this topic on one of blog postings http://www.lysimetry.com/blog/

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Re: Accuracy of wick lysimeter

LeoR — Wed, 14 Mar 2012 16:41:03 -0700

The accuracy of the wick lysimeter is going to vary depending on the type of soil that it is installed in. The Drain Gauge has the ability to measure drainage with sub millimeter accuracy but there is still the potential for flux divergence and convergence. The optimal setting for a wick lysimeter is going to be in a coarse textured soil.

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Re: Equilibration of wick lysimeters

LeoR — Wed, 14 Mar 2012 16:40:28 -0700

Equilibration time is going to vary depending on the type of installation that is conducted and the setting in which it is installed in. If you use an intact core in a cultivated field the equilibration time will likely be very quick. In some other cases I have heard of equilibration times from 6 months to a year. It just depends on the settings.

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Re: Water balance of short term, shallow root crops

LeoR — Wed, 14 Mar 2012 16:39:41 -0700

If you do not want to permanently install a lysimeter the water balance residual method may be a better method for this type of project. ET measurements using the eddy covariance method along with measurements of soil storage, precipitation, and runoff will be less permanent than installing a lysimeter.

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Water balance of short term, shallow root crops

Nick — Wed, 14 Mar 2012 13:33:57 -0700

What would you recomend for short term, shallow root crops (60 day or less) to understand
water balance.

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Equilibration of wick lysimeters

Nick — Wed, 14 Mar 2012 13:32:35 -0700

What is the equilibration time for wick lysimeters?

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Accuracy of wick lysimeter

Nick — Wed, 14 Mar 2012 13:31:53 -0700

What is the accuracy of your wick lysimeter?

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Suction cups vs. lysimeters

Nick — Wed, 14 Mar 2012 13:31:28 -0700

Are suction cups lysimeters?

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Installation services

Nick — Wed, 14 Mar 2012 13:30:56 -0700

Do you provide installation services or help for some of these systems?

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Oxygen loss?

Nick — Wed, 14 Mar 2012 13:30:31 -0700

Often omitted in the water balance equation is the oxygen liberated from water in
photosynthesis. Is this too minor a loss to consider?

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Lysimeters vs. Piezometers

Nick — Wed, 14 Mar 2012 13:29:46 -0700

Can you compare and contrast lysimeters vs. piezometers?

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Improvements in tension controlled lysimeters

Nick — Wed, 14 Mar 2012 13:29:12 -0700

What are the simplifications of the controlled tension lysimeters that have occurred compared
to earlier versions?

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Lysimeters in potatoes

Nick — Wed, 14 Mar 2012 12:09:28 -0700

If I want to carry out potato related study, what lysimeter techniques would you suggest me to take?

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