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Posts by Lauren Crawford

Reforestation Challenges Around the World

In the conclusion of our three part series on the reforestation of Banguet province in the Philippines, we asked Dr. Anthony S. Davis, Tom Alberg and Judi Beck Chair in Natural Resources at the University of Idaho, Loreca Stauber, one of the visionaries behind the project, and Kea Woodruff, former U of I Nursery Production and Logistics Associate, now at Harvard University, to explain some challenges associated with teaching reforestation to different cultures.

Ground view of a forest of bamboo looking up

Even with increased environmental awareness, we’re still losing almost thirty million acres of forest globally every year.

What are some of the cultural challenges?

Anthony: As I spend more and more time looking at international forests, I realize that we’re losing forests at a phenomenal rate. Even with all of our awareness about where we get supplies, where trees come from, where wood comes from, and where paper comes from, we’re still losing almost thirty million acres of forest globally every year. That’s terrifying to me. What’s even worse is that most of it comes from countries that don’t have environmental controls.  They don’t have systems in place that keep them from cutting down all the trees. Often, when we cut trees down for forestry, we replant. But, when you start to work in countries where that’s not valued or not part of the culture or the system, then a huge problem emerges.

How do you teach people to grow trees that can survive in their native terrain?

Anthony: There isn’t a lot of knowledge globally about how to grow high-quality tree seedlings. I’ve gotten really interested in the question of how to take a tree seedling which is grown in a nursery, where it essentially has all of the water and all of the nutrients it could possibly ask for, and get it into a condition where it’s likely to survive somewhere extremely harsh: with limited nutrients and water.  How do you get it to the point where it’s able to overcome those challenges?

There are two ways to look at that. One is to get more water to that seedling after it’s planted. The other is to make sure that the seedling you’re planting has its best possible chance of developing a root system that can access water that might not normally be available in those six inches where healthy roots are located when it’s first planted. Based on work that’s be done here at the University of Idaho in graduate student projects over the years, we found that if you can grow a seedling in a healthy manner in the nursery, it’s more likely to grow roots or access water that previously they might not have been able to access.

Researcher works on one of the water tanks that will supply water to the Benguet nursery in the Philippines

Working on one of the water tanks that will supply water to the Benguet nursery in the Philippines. The project is proceeding nicely after a series of setbacks: a destructive typhoon, slides that had to be cleared, 2 deaths, 1 funeral, and electrical power interruptions.

What challenges the plants after they leave the nursery?

Anthony: If that seedling can get roots down and access water, it starts to grow.  The beauty of reforestation, in general, is that it’s very simple; it can be very easy to get trees to grow. However, what often happens is you have a social element that overlaps the biological element. Some of it could be a lack of education, where people don’t understand that a large amount of foliage or leaves on a tree means that you need more water. You think about that image of success: people want to plant the biggest tree possible. That might work in a yard, but it really doesn’t work in a reforestation situation.

What are the challenges of establishing a nursery in a place like the Philippines?

Kea: In the place like the Philippines where resources aren’t necessarily as available, it becomes a huge challenge just finding the right kind of media or container. Also, there’s a decentralization of the knowledge resource itself. While we were there, we had the opportunity to meet with different government agencies, and there are definitely people who know a lot about the species that are available and how to grow them, but in terms of that information being disseminated and widely available to the public, that’s a challenge. The techniques that will be needed to actually produce a seedling resource need to be addressed.  

Loreca:  The basic thing is a good nursery. That has been a problem. In the past, the government, in an effort to green the Philippines, has given seedlings, but oftentimes, these seedlings are so poor in quality that they don’t survive in out planting.

Coffee beans thriving in the tropical Philippines

Coffee beans will thrive in the tropical Philippines.

How can you help other cultures to succeed at reforestation?

Anthony: During some work I was doing in the Middle East, in Lebanon, we found that communicating to people what a high-quality seedling became really important. You teach them about quality, defining it in terms of how much water a plant needs to survive, or how a plant has to grow in order to colonize a site.  We had a lot of success with the project there, getting people to understand that there was a problem in only looking at above ground information in terms of what makes a high-quality seedling. Really, when the roots are what’s driving survival, they’re looking at the wrong part of the picture.

How do you teach people to think beyond the nursery?

Anthony: Our work in Lebanon coincided with a project in Haiti. In Haiti, we had a former student who had been here at the University of Idaho who asked for help starting a nursery. These same conversations occurred: what is a healthy seedling, what is likely to survive, where do you get your seed, how long do you grow it for, when do you plant it?  We were able to have conversations around all of the elements that go into growing trees.

I remember clearly the “aha” moment where this young woman said, “We’ve been doing it wrong! We’ve always focused on growing as many seedlings as possible, and we haven’t worried about quality.”

See it live

Watch a video where Anthony talks about his work.


You can learn more about the reforestation programs that the University of Idaho nursery is involved with here.

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Philippines Part 2: Overcoming Native Challenges with Remote Data

In one of the first agroforestry efforts in mountainous terrain, Moscow, Idaho community leader Loreca Stauber, Dr. Anthony S. Davis, Tom Alberg and Judi Beck Chair in Natural Resources at the University of Idaho, and their partners have initiated a program where U of I students travel overseas to work with farmers of Banguet province in the Philippines to develop the skills needed to grow high quality tree seedlings.  Local vegetable farmers have historically terraced the mountains that have been forested so they could grow monoculture crops, causing serious erosion (read about it here).  The land has degraded so much that the Philippine government has stepped in: warning farmers to begin conservation techniques, or they will take away the land and manage it themselves.

People building a local nursery in Benguet

Building a local nursery in Benguet.

Inspiring Students to Look at the Big Picture

One of the steps in helping local farmers to solve this problem is to create a local nursery where they can start growing native plants and trees.  Fortunately, the University of Idaho has operated a tree nursery for over one hundred years, and they understand how to grow trees. Dr. Davis specializes in setting up native nurseries for growing native plants all over the world. He says, “I want our students to be exposed to this because we’re graduating students who should be problem solvers, who should be able to look at the biggest challenges and contribute their own ideas towards resolving those challenges.”

Loreca Stauber adds, “We are part of the world and the world is part of us. The students can do more than just get their degree and find a job. Anthony and Kea, when they do this, inspire students to look at a bigger world than they are currently living in.”

Training Students to Understand Native Terrain and Resources

Davis says a good plan needs to take local conditions into account:  “The principles of growing trees are actually universal. It doesn’t matter whether you’re in Haiti, Lebanon, Idaho, or in the Philippines. Those principles are the same and they’re readily transferable. It’s how you adapt them to unique local situations that makes a difference.”

Close up on bamboo stalks

“It’s not really about the best way to grow a plant in a greenhouse environment; It’s about the best way to grow a plant that will also survive on its outplanting site.”

Kea Woodruff, former U of I Nursery Production and Logistics Associate, now at Harvard University, says they train the students who go overseas on the “target plant” concept:  designing a growing regime based on what the plant is going to need in its future home. She says, “It’s not really about the best way to grow a plant in a greenhouse environment; It’s about the best way to grow a plant that will also survive on its outplanting site. Determining what the outplanting site is and what each species will need to survive on that outplanting site is what determines greenhouse operations.”

Dr. Davis says you need to consider native resources when doing these types of projects.  “There could be plumbing there, but there’s no guarantee that when you turn the system on, the tap water will come out. That depends on the seasonality of the rains. It’s part of why we wanted the project partners (the farmers) to have data loggers: so we could look at the data together and get a better feel for when water is most abundant and when it’s most scarce, so it can be stored for later use.”

Overcoming Native Challenges with Remote Data

Decagon (now METER) donated data loggers to the program so that Dr. Davis and other people on the team could look at data with the farmers in the Philippines and advise them when to irrigate.  Davis says, “One of the things that’s most important in trying to set up a very remote nursery and manage the production in that nursery from approximately four flights, twelve hours, and twelve time zones away, is knowing what’s going on. There are things that are really easy to ask, like could you send me a picture every Wednesday and Saturday of the nursery, or could you measure the height and the diameter of the seedlings? What’s much harder to tell is how much water is coming in, or what the temperature was during the day or night, because those require people to be monitoring things at a greater frequency than is often possible. If we know how much water is coming into the nursery from rainfall, we can build collection systems so that we can manage where that water goes later on.”

Managing data for both the short and long term is critical, says Davis, because it’s often whether there was rainfall in the predicted amount, and at the right time, that determines whether a seedling establishes or not.

Next week:  The conclusion of our three part series: an interview with Dr. Davis and Kea Woodruff, discussing the cultural challenges of reforestation in different countries.

Acknowledgements:  The SEAGAA agroforestry project in Benguet is agro and forest; the farmers received a grant from the Rufford Foundation based in the UK to build a greenhouse and much of the water catchment system and auxiliary structure that go with a nursery facility.  They also received a sizable grant from the Philippine government to launch mushroom growing as a necessary complement to help support long-term agroforestry. The project is beyond reforestation – it is the growing of trees, shrubs, ground cover, the restoring of watersheds, creating livelihoods, the rebuilding of soil fertility and integrity, the revival of springs which have vanished with the removal of perennial flora, and the restoring biodiversity to bring back the natural checks and balances of a natural ecosystem.

Download the “Researcher’s complete guide to soil moisture”—>

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Reforestation in the Philippines (Part 1)

In the mountainous Benguet province of the Philippines, farmers grow up to three crops of vegetables a year. Their mountain vegetable farms exist at the expense of original forest cover, causing tremendous erosion difficulties. To counteract erosion and preserve the watershed as well as promote reforestation, the Philippine government issued a mandate: farmers must find alternatives that restore the watershed or lose their land.

Arial view of rice terraces in the Philippines

Rice terraces in the Philippines

An Agroforestry Alternative

Loreca Stauber is no scientist, but she loves Benguet, and a letter from her friend, a scientist living in the Philippines, inspired her with the vision of teaching farmers to reforest the mountains and grow vegetables amongst the trees.  

Her friend writes, “We envision mountain farms as forest ecosystems whose primary social responsibility to the communities around and below is to be part of responsible watersheds that court, catch, store and gradually share water. We see mountain farms that are not prone to soil erosion or leaching: cultivated with minimal chemical inputs and tillage that will allow the natural buildup of biomass, organic matter, helpful organisms and fauna. We think of forest ecosystems that may not make millionaires of its farmers for one generation and heavy debtors even before the next. Rather, we envision forest farm ecosystems that are self-sufficient and self-sustaining. We are working on demonstrating forest ecosystems that can substitute for monocrop vegetable farms that deplete and leach the soil, pollute watersheds and are self-destructing.”  

Realizing the problem in the Philippines could be solved by reforestation, Loreca emailed Dr. Anthony S. Davis, Tom Alberg and Judi Beck Chair in Natural Resources in the University of Idaho’s Department of Forest, Rangeland, and Fire Sciences.  The U of I operates a 100-year-old nursery specializing in growing hardy tree seedlings. Dr. Davis recalls, “The email she sent me said, “I think you should do something about this,”  and I thought, “Actually I agree. I think we should do something about this.  So we began to screen the idea, asking: are there partners?  Is it a good idea?  Does it fit with this little thing that we do really well, which is essentially teaching people how to grow tree seedlings, and is there an educational component that’s valuable for our students?  When those check boxes lined up, then it was a matter of taking advantage of that opportunity and seeing where it could go.”

Green forested mountains in the Philippines

Forested mountains in the Philippines

Determining What Already Works

Together, they and other partners started a program in which U of I students went overseas to teach the people of Benguet how to grow trees, with the goal of moving the land toward agroforestry.  They wanted to grow a forest ecosystem (trees, shrubs, and ground cover) along with annual crops. Kea Woodruff, former U of I Nursery Production and Logistics Associate, now at Harvard University, traveled to the Philippines with an interdisciplinary team of undergraduate and graduate students to look at what agroforestry projects were already working and to conduct a needs assessment.    She says, “I saw a wide variety of landscapes in the areas that we were. One woman decided on her own that she was going to practice agroforestry, and people come and view her land as a demonstration site. It has mature bamboo, coffee trees, and mature Benguet pine. It really looks like what you would expect the native forest to look in an area like the Philippines.”

Kea said there were also intermediate sites where there are Benguet pines and some coffee with row crops blended in, such as strawberries and squash. She adds, “There’s clearly great potential to grow different species on these lands if we can help figure out the best way to use the resources that are available.”

Next week: Learn how partners in the project have been able to use native resources in the quest to reforest erosion-plagued Benguet.

Take our Soil Moisture Master Class

Six short videos teach you everything you need to know about soil water content and soil water potential—and why you should measure them together.  Plus, master the basics of soil hydraulic conductivity.

Watch it now—>

Download the “Researcher’s complete guide to soil moisture”—>

Download the “Researcher’s complete guide to water potential”—>

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Water Potential/Water Content:  When to Use Dual Measurements

In a previous post, we discussed water potential as a better indicator of plant stress than water content.  However, in most situations, it’s useful to take dual measurements and measure both water content and water potential.  In a recent email, one of our scientist colleagues explains why: “The earlier article on water potential was excellent.  But what should be added is an explanation that the intensity measurement doesn’t translate directly into the quantity of water stored or needed. That information is also required when managing water through irrigation.  This is why I really like the dual measurement approach. I am excited about the possibilities of information that can be gleaned from the combined set of water content, water potential, and spectral reflectance data.”

Field plantation with a sprinkler in the middle of it

Potato field irrigation

Managing Irrigation

The value of combined data can be illustrated by what’s been happening at the Brigham Young University Turf Farm, where we’ve been trying to optimize irrigation of turfgrass (read about it here). As we were thinking about how to control irrigation, we decided the best way was to measure water potential.  However, because we were in a sandy soil where water was freely available, we also guessed we might need water content. Figure 1 illustrates why.

Turf farm data concerning water potential diagram

Figure 1: Turf farm data: water potential only

Early water potential data looks uninteresting; it tells us there’s plenty of water most of the time, but doesn’t indicate if we’re applying too much.  In addition, if we zoom in to times when water potential begins to change, we see that it reaches a stress condition quickly.  Within a couple of days, it is into the stress region and in danger of causing our grass to go into dormancy.  Water potential data is critical to be able to understand when we absolutely need to water again, but because the data doesn’t change until it’s almost too late, we don’t have everything we need.

Turf farm data dual measurements data diagram

Figure 2: Turf farm data, volumetric water content only

Unlike water potential, the water content data (Figure 2) are much more dynamic. The sensors not only show the subtle changes due to daily water uptake but also indicate how much water needs to be applied to maintain the root zone at an optimal level. However, with water content data alone, we don’t know where that optimal level is. For example, early in the season, we observe large changes in water content over four or five days and may assume, based upon onsite observations, that it’s time to irrigate. But, in reality, we know little about the availability of water to the plant. Thus, we need to put the two graphs together (Figure 3).

Water potential and vol. water content diagram

Figure 3: Turfgrass data: both water potential and volumetric water content together.

In Figure 3, we have the total picture of what’s going on in the soil at the BYU turf farm. We see the water content going down and can tell at what percentage the plants begin to stress.  We also see when we’ve got too much water: when the water content is well above where our water potential sensors start to sense plant stress. With this information, we can tell that the turfgrass has an optimal range of 12% to 17% volumetric water content. Anything below or above that range will be too little or too much water.  

Soil water potential and volumetric water content diagram

Figure 4: Turfgrass soil moisture release curve (black). Other colors are examples of moisture release curves for different types of soil.

Dual measurements will also allow you to make in situ soil moisture release curves like the one above (Figure 4), which detail the relationship between water potential and water content.  Scientists can evaluate these curves and understand many things about the soil, such as hydraulic conductivity and total water availability.

Download the “Researcher’s complete guide to water potential”—>

Download the “Researcher’s complete guide to soil moisture”—>

Get more information on applied environmental research in our

Scientists and Greenhouse Growers Collaborate to Help the Environment

Bodies of water across the world face extreme pressure from non-point source pollution.  It’s easy to get overwhelmed by the sheer enormity of this problem, but it didn’t daunt Dr. John Lea-Cox, Research and Extension Specialist for horticulture at University of Maryland.  Dr. Lea-Cox was acutely aware that agriculturally applied fertilizers threatened serious harm to the Chesapeake Bay area near his home. Using an early version of METER’s water content sensors, he began to put together a system that could monitor water status in nursery operations. The effort was based on the work of Dr. Andrew Ristvey (now a colleague at Maryland) who showed water savings of more than 50% during his PhD work using TDR sensors in pots growing ornamental plants.  Dr. Lea-Cox and his colleagues wanted to ultimately develop a network of soil moisture and environmental sensors that would help greenhouse and nursery growers know when to turn on and off their water. Their goal was to reduce nutrient and water use through more efficient application.

Close up of a yellow flower with red tipped petals

How did Dr. John Lea-Cox, Research and Extension Specialist for horticulture at University of Maryland, convince nursery growers to reduce water and fertilizer use?

Convincing Growers

One hurdle facing Dr.Lea-Cox was that water savings didn’t resonate with all growers.  But he soon realized that better irrigation control influenced things growers did care about: higher quality crops, lower mortality rate, and less spending on pesticides.  Dr. Lea-Cox discovered that when he showed growers their moisture sensor data, they were hooked. One snapdragon grower, who found that he could use the sensors to produce a more lucrative A grade crop, said he would not like to go back to the days before sensors. “My gosh, it would be like going back ten years. It would be like trying to measure the temperature in a room without a thermometer. We are totally dependent on them.”

Pink orchids growing in a nursery super green nursery

Orchids grown in a nursery.

Finding Collaborators

Dr. Lea-Cox was not only good at convincing growers, but scientific collaborators as well.  Building on this team’s initial findings, he organized a project to develop water retention curves to tie the amount of water in pots to what was actually available to the plant for several different mixes of potting soil. He realized that moisture measurements were practically useless to growers without a mechanism for viewing them all in one place, so he began to look for collaborators who could build an integrated, wireless system to get root zone information to the nursery grower’s computer and allow them to set irrigation limits and automate their systems based on soil and weather data.  

The resulting collaboration was a group of diverse scientists and commercial growers who could study root behavior, plant-environmental interactions, the performance of the plants, and individual grower interaction with the system.  After a few years of testing, the group received $5M in funding from the Specialty Crops Research Initiative (SCRI) Program over five years to improve horticulture for ornamental plants grown in the U.S.

Lauren Crawford, METER’s soils product manager, says that the resulting collaboration was unique. “It was amazing that an instrumentation company, a research group, and commercial growers were able to work so well together. It was because of the trust we had for each other. We were very transparent about what we were doing, even when we knew that transparency would be difficult. The result was that we were able to make tremendous progress in both science and technology.”

Watch two virtual seminars highlighting SCRI research given by scientists Marc Van Iersel and John Lea-Cox.

Download the “Researcher’s complete guide to soil moisture”—>

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Lessons from the Field – Sensor Installation Considerations

In the Midwest, government incentives are sometimes provided to convert marginal lands to switchgrass, a leading choice for bio-energy feedstock production.  Michael Wine, a researcher at New Mexico Tech, wanted to investigate whether switchgrass’s deeper root systems would affect the water cycle both during and after crop establishment.  In the first stages of his investigation, he learned that many factors need to be considered when determining the optimal location for sensor installation.

Aquifer Recharge

Wine used Gee passive capillary lysimeters to determine deep drainage under natural vegetation, wheat, and switchgrass in order to improve our understanding of both the baseline water cycle and the water budget associated with a switchgrass monoculture in Woodward, Oklahoma.  He put the lysimeters and some soil moisture (capacitance) sensors into the Beaver-North Canadian River Alluvial Aquifer to look at recharge, but ran into challenges with sensor installation from the start.

Climate Considerations

One thing Wine learned was that biofuels aren’t very successful in his research location– there wasn’t enough water to support switchgrass.  He says, “Most places here may have no precipitation recharge for a great many years. But there are sites, such as sub-humid environments, where you could get a whole lot of infiltration in a very short time.” In hindsight, Wine says he “would have increased his use of preliminary data to more efficiently determine the frequency of recharge events.”

Using Preliminary Data to help Site Instrumentation

Wine learned that it’s important to think about the time constant of your system when siting instrumentation and that preliminary data are crucial. He says, “Before sensor installation, I did a chloride mass balance which helped me determine where I should install the lysimeters.”  He had been planning to put them at watersheds at the USDA-ARS Southern Plains Range Research Station, but the chloride mass balance showed there hadn’t been a recharge event at that site in the past 200 years. So he chose to install the lysimeters at the USDA-ARS Southern Plains Experimental Range, located in the Beaver-North Canadian River Alluvial Aquifer, a site with coarser soil and higher permeability.

Wine also thinks numerical modeling could have been useful in determining placement. “In siting the instruments, numerical modeling would’ve been a big help because we could have predicted the likelihood and frequency of recharge events.  So I think preliminary data, numerical modeling, and environmental tracers can all help in terms of where to place these research devices.”

a baby calf walking towards the photographer with other cows, who are collectively walking through a field

After long absences, Wine often had to repair damage caused by cattle.

Proximity to Research Site

Another challenge was that the researchers were located in Stillwater, Oklahoma, far from their research site. The experiment was protected by fences, but after long absences,  Wine often had to repair damage caused by cattle.  “I really need to hand it to these instruments that can be trampled numerous times by cows and the battery compartment filled up with water,” Wine says. “They just needed to be dusted off, dried out, new batteries inserted, and they worked great.”  Wine adds that researchers need to consider the distance between their office and their research site because in his case, the cows would have been less of an issue if it had been a fifteen-minute drive instead of three hours each way. He adds, “Selecting a nearby research site would have allowed us additional flexibility in our experimental methods; for example, with a nearby site we could have more easily conducted artificial rainfall simulations if a particular year turned out to be too dry for natural recharge events to occur.”

Proper Siting of Equipment Makes a Difference

Once Wine determined the correct placement of his instruments, he was finally able to get some interesting data.  He says, “There are large pulses of focused recharge that do occur in certain places, and we quantified one of those pulses following a storm with one of the lysimeters.  We’ve got about a year’s worth of data. Since we installed lysimeters at adjacent upland (diffuse recharge) and lowland (concentrated recharge) sites, we succeeded in observing large differences between the recharge fluxes at these nearby sites.”  Wine’s plan is to see if he can replicate the results of the lysimeter experiment using numerical modeling, because he says, “the data look reasonable, but I’d like to confirm the measurements due to the cows playing havoc with our site.”  Wine is excited as these lysimeters are yielding the first direct physical measurements of diffuse and concentrated groundwater recharge in the Beaver-North Canadian River Alluvial Aquifer, and he’s optimistic that his numerical modeling will match this unique time series of direct physical measurements of groundwater recharge.

Download the “Researcher’s complete guide to soil moisture”—>

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The History and Future of Water Potential

I often hear researchers complain about the accuracy of our TEROS 21 water potential sensors.  We still have room to improve, but we’ve certainly come a long way! People have been attempting to make water potential measurement in the field for over 100 years. The following is a brief overview of the evolution and history of water potential measurements over that time.

Pre-MPS-1 Prototype

Pre-MPS-1 prototype.

Livingston Discs

The Livingston disc, developed in 1908, was one of the first attempts at determining water potential in the field.  The Livingston Disc was actually a primitive, manual version of the technology used in our MPS6 ceramic disc.  Here is how it worked:  first, you’d weigh the dry disk, then put it in the soil and let it equilibrate.  After that, you would dig it up and weigh it again.  Using the water retention curve of the disc, you could then determine the water potential.

Gypsum block

In the 1940s gypsum block sensors were invented as the first solid matrix equilibrium technique for water potential.  This method tried to continuously sense water potential with a simple electrical conductivity measurement in a solid porous (and naturally occurring) gypsum matrix.  However, because naturally occurring gypsum doesn’t have a consistent pore size distribution and it degrades over time, the instrument was not very accurate.

1940's Gypsum Block Sensors

In the 1940’s gypsum block sensors were invented as the first solid matrix equilibrium technique for water potential. Image:


In the 1960’s a liquid equilibration technique called tensiometry was discovered that allowed water potential measurement with good accuracy even in the presence of positive pore water pressures.   Tensiometers work extremely well in wetter soils with water potentials between 0 and -80 kPa and should be the choice for all wet soil applications, especially above -9 kPa where the MPS6 will not work (the air entry value for its ceramic is -9 kPa).  However, when the soil dries out the water under tension in the tensiometer eventually cavitates, causing the output to be useless until they are refilled.  Thus solid equilibrium techniques like the TEROS 21 are the best choice across the dry range.

1960 Tensiometer

Tensiometers are the most accurate way to measure water potential in the field in the wet range, but are limited to the plant optimal range of about -100 kPa and above.

The Evolution of Ceramic Discs

We learned with the gypsum blocks that one of the challenges in solid matrix water potential measurement is finding a material that will create the same water retention curve every time. In quest of this goal, the ceramic discs in sensors like the TEROS 21 have taken years of development.  Because of the limited range of the tensiometer, we wanted to develop a water potential sensor that could measure over a larger range.  The hardest part about developing that ceramic was getting a variety of pore sizes so the instrument could read said wide range of water potentials.  This started years ago in the lab of Dr. Gaylon Campbell at Washington State University where his technician, Kees Calisendorf, experimented over a long period of time to come up with the perfect recipe.


The MPS1 was our original matric potential sensor released in 2001. It allowed for long-term monitoring in the field because, unlike gypsum, the ceramic did not degrade over time.

Even after we found a consistent ceramic, there were still outliers.  So creating a calibration method was essential to making an accurate sensor.  The first challenge was to be able to store calibration points in the sensor, which required a microprocessor.  The second, and more difficult task, was to establish a method to calibrate large numbers of sensors at once.  We tried many different approaches like pressure plate, equilibration over salt solutions, and even centrifugal force, but nothing worked.  Finally, in a discussion with our partner, UMS, we discovered the key.  We now can accurately calibrate 50 sensors at a time in only 12 hours.  Still, even with these advanced techniques, we only have a sensor with an accuracy of plus or minus 10%, but considering the history of how hard it’s been to develop consistent ceramic, this accuracy is exciting for the range that we can get.


The MPS 2 was our second matric potential sensor which offered two-point calibration and a temperature sensor, improving accuracy.

What’s Next?

Now that we’ve created a reliable calibration method, we can turn our attention toward further improving the sensor measurement range as well as its accuracy.  Testing different ceramics, or other porous media, may hold the key to a solid equilibrium technique sensor reading all the way to 0 kPa, eventually replacing the need for tensiometers in the field.


The two key innovations in the MPS6 (now called TEROS 21), released in 2014, are the addition of a microprocessor to the sensor and fast, accurate equilibration at multiple points.

Take our Soil Moisture Master Class

Six short videos teach you everything you need to know about soil water content and soil water potential—and why you should measure them together.  Plus, master the basics of soil hydraulic conductivity.

Watch it now—>

Download the “Researcher’s complete guide to water potential”—>

Download the “Researcher’s complete guide to soil moisture”—>

Get more information on applied environmental research in our

Water Content Innovation Involves Growing Pains

Months ago, I was reading about the tragic test-flight crash of the Virgin Galactic passenger rocket plane and noting that there was a lot of criticism of that company for it’s “risky space venture.”  In the midst of the heartbreak I felt at the deaths of the two pilots, as an innovator, I can somewhat sympathize with the Virgin Galactic Company in the realization that historically, innovation has involved risk.  If you think about airplane development in the early 1900’s, every year 20% of pilots died because of malfunctions on airplanes (“By the spring of 1917, the life expectancy of a British pilot was put at eight days.” Van Creveld, The Age of Airpower, p. 28).  Today we worry about the safety of air travel much less because people were willing to go through years of painful learning, and because of that learning, we no longer use trains as our fastest transportation.

Thankfully, no one’s life is on the line with Decagon sensor innovation.  However, similar to early airplanes and the new rocket plane, when we release an instrument that is completely new (like our circuit board water content sensors), there are occasional problems that are not accounted for in our extensive laboratory and field testing.  In light of this, we are grateful for scientists who are willing to give us feedback in order to aid innovation and advancement of science and technology.  Here is an example of how scientists became our collaborators in developing a new product that helped to advance their discipline.

In 2000 we made our first water content sensor where we put the circuit board on the sensor itself, rather than a data logger.   In advance of its release, we made a version of the sensor that was flexible with the idea that it would have excellent contact by conforming to the soil.  In theory, it looked great, but when it was put in the ground, the sensor flexed and popped the components off the circuit board.  Thanks to testing feedback, we made more rigid, 20cm long sensors, and the components had no more trouble.

Greenhouse with Plants Hanging from the Roof

Researchers loved the instrument but wanted shorter ones to put in greenhouse pots.

After this problem was solved, researchers loved the instrument but wanted shorter ones to put in greenhouse pots.  So we made the shorter ones.  Scientists then became concerned that the sensors were sensitive to salinity in higher electrical conductivity conditions.  Coincidentally, components became available to raise the frequency to 70 MHz, which is much less sensitive to electrical conductivity. Thus, because scientists were willing to partner in the development process and learn with us, we have developed a sensor that is affordable, cutting-edge technology which advanced the discipline of soil science.

We love to partner with scientists in the pursuit of knowledge. A researcher at a conference once said to one of our scientists, “I hate your stuff…for the first couple of months.  But then you guys take your lumps, make it better, and then I buy all your stuff.”  He was saying this in jest because it certainly doesn’t happen with many of the products we release.  But when it does, we appreciate the dedicated support of our scientist friends who enjoy learning along with us to make the same kind of advancement that helped the world move from trains to air, and now onward into commercial space travel.

Download the “Researcher’s complete guide to water potential”—>

Download the “Researcher’s complete guide to soil moisture”—>

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The Spirit of the Grant Harris Fellowship

The Grant Harris Fellowship was conceived in 2009 by  METER‘s (formerly Decagon Devices) marketing group as an opportunity for METER to give back to the science community.  The idea was to create a partnership between METER and researchers so that we could provide instrumentation and be a kind of “scientific friend” to graduate students: giving them experience crafting a proposal, reviewing their ideas, offering feedback, and encouraging those projects that seemed the most promising and exciting to us as scientists.

Grant Harris fellowship

Grant Harris standing in the doorway of METER’s first office in 1987.

When we thought about this opportunity we wondered…who would we name this fellowship after? It was an easy decision when we realized that the principles upon which METER is based come from academia through our founder, retired soil science professor Gaylon Campbell and his father-in-law, Grant Harris, who was a professor and department head of Rangeland Ecology at Washington State University.

Grant Harris fellowship

He lived in a tiny outpost of a house, taking care of sheep-grazing rangeland in a high alpine meadow area, far removed from civilization.

Grant Harris started his career at the beginning of the depression, so when he got married he quickly needed to find a way to support his growing family.  At that time in history, there was not as much college funding or support.  Instead of having the opportunity to attend graduate school, Dr. Harris was forced to start work immediately after obtaining his B.S. for the U.S. Forest Service, managing rangeland in Montana. He lived in a tiny outpost of a house, taking care of sheep-grazing rangeland in a high alpine meadow area, far removed from civilization.

“Scientific Instrumentation has made a lot of progress since I was first exposed to research, working at the Desert Range Experiment Station in 1935 as an undergraduate at Utah State University.  Back then research was 3 parts wits, 6 parts labor, and 1 part instrumentation. I still remember in 1939 measuring the absorption of water into the soil profile using old whisky bottles and corks.

It is amazing to see the time and labor saving devices now available.  We are proud of Decagon’s heritage in producing instrumentation for soil physics.” – Grant Harris

It was only later, after five years of service in the U.S. Navy during WWII, that he finally got the chance to further his education. He returned to school to earn an M.S. and a PhD, and because of his difficult path in obtaining those degrees, he placed a high value on education and an even greater value on the providing of opportunities for research.

Grant Harris fellowship

He placed a high value on education and an even greater value on the providing of opportunities for research.

During his career, Dr. Harris was able to reach out and touch the lives of many students, not only in the U.S. but from all over the world.  He spent time in other countries researching and helping to provide basic science to people throughout his career as a rangeland ecologist.  The Grant Harris Fellowship provides that same learning opportunity for graduate students today where, in the spirit of this legacy that Grant Harris provided, we continue his passion for encouraging research in a direction that will help us understand more about the natural environment.

Colin Campbell, Decagon’s VP of Research and Development commented on the “Spirit of Grant Harris,” during a recent interview.  “As we thought about this opportunity to give back to the research community, we thought of my grandpa, who had a great passion for providing people the chance to learn and grow through the beauty of science.  Thus the objective of the Harris Fellowship is to provide student researchers additional opportunities to dream up new ways of doing things that are going to be successful and also to provide support to those researchers so they can accomplish their goals.”

Click here to learn more about how to apply for the annual Grant Harris Fellowship

Get more information on applied environmental research in our

Download the “Researcher’s complete guide to soil moisture”—>