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Water Potential 101: What It Is. Why You Need It. How To Use It.

Soil is no longer a black box 

Advances in sensor technology and software now make it easy to understand what’s happening in your soil, but don’t get stuck thinking that only measuring soil water content will tell you what you need to know.

Water content is only one side of a critical two-sided coin. To understand when to water, plant-water stress, or how to characterize drought, you also need to measure water potential. 

Better data. Better answers.

Soil water potential is a crucial measurement for optimizing yield and stewarding the environment because it’s a direct indicator of the availability of water for biological processes. If you’re not measuring it, you’re likely getting the wrong answer to your soil moisture questions. Water potential can also help you predict if soil water will move, and where it’s going to go. Join METER soil physicist, Dr. Doug Cobos, as he teaches the basics of this critical measurement. Learn:

  • What is water potential?
  • Why water potential isn’t as confusing as it’s made out to be
  • Common misconceptions about soil water content and water potential
  • Why water potential is important to you

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Presenter

Dr. Cobos is a Research Scientist and the Director of Research and Development at METER.  He also holds an adjunct appointment in the Department of Crop and Soil Sciences at Washington State University where he co-teaches Environmental Biophysics.  Doug’s Masters Degree from Texas A&M and Ph.D. from the University of Minnesota focused on field-scale fluxes of CO2 and mercury, respectively.  Doug was hired at METER to be the Lead Engineer in charge of designing the Thermal and Electrical Conductivity Probe (TECP) that flew to Mars aboard NASA’s 2008 Phoenix Scout Lander.  His current research is centered on instrumentation development for soil and plant sciences.

Weather Data: Virtual, In-Field, or Regional Network—Does It Matter?

Which data source is better?

In the world of specialty crops, there is disagreement on how well weather-driven insect, disease, and frost prediction models actually perform. Dr. Dave Brown, former director of Washington State University’s AgWeatherNet spent years comparing different weather data sources and how those data affect the accuracy of common environmental models used by orchard growers. In this 20-minute webinar, he shares the surprising things he learned.

Decrease chances of crop damage with one simple practice

Find out how you can increase the accuracy of your predictive models and decrease frost, insect, and disease incidents by doing just one thing differently—improving the quality of your weather data. Discover:

  • Microclimates: what are the conditions like inside a crop canopy versus outside?
  • Virtual data vs. weather station data: Which is better?
  • How do site-specific weather data vs. regional network data compare?
  • How much does a small decrease in data quality affect the accuracy of your models?
  • What’s the value of in-orchard measurements?
  • What are some best practices for higher data quality?

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Presenter

For 20 years as a faculty member at Montana State University and Washington State University (WSU) Dr. Dave Brown pursued research on soil sensors, spatial data science, and digital agriculture. At both universities, he served in many leadership roles for major research projects, academic programs, and most recently as Director of the WSU AgWeatherNet program. In this capacity, Dr. Brown hired and supervised a team of meteorologists who pursued research and extension activities focused on evaluating and improving the quality of weather data used for agricultural decisions.

Episode 9: Pioneers of Environmental Measurement

What was the life of a scientist like before modern measurement techniques? In our latest podcast, Campbell Scientific’s Ed Swiatek and METER’s Dr. Gaylon Campbell discuss their association with three pioneers of environmental measurement.

Learn what it was like to practice science on the cutting edge. Discover the creative lengths they went to and what crazy things they cobbled together to get the measurements they needed.

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Ranching, Wildfires, & Global Sustainability

Check out our latest podcast, where Dr. Richard Gill discusses his global research projects including climate change on the Wasatch Plateau, ranch sustainability in Colorado, reef studies in Samoa, and wildfires in the Mojave Desert.

Landscape in Samoa

He focuses on the connection between the ecology of a place and the communities of people that inhabit it, and how scientists can protect socially and ecologically vulnerable populations by collaborating equally with them. Unless they’re sharks. He found out they’re typically not open to collaboration.

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Learn more about Dr. Gill

Richard Gill, PhD, is an ecologist and department chair in biology at Brigham Young University.

Links to learn more about Dr. Richard Gill:

Richard’s biography

Richard’s ResearchGate

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Ticking Time Bomb: Climate Change In Antarctica

Dr. Marco Bittelli, soil physics wizard and pretty much the most interesting guy we know, discusses his exciting research projects in Italy and Antarctica. Plus, he shares insights on cutting-edge measurement methods, climate change, jazz guitar music, and more.

Marco Bittelli, PhD, is an associate professor in the Department of Agricultural and Food Science at the University of Bologna in Italy.

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Links to learn more about Dr. Marco Bittelli

Marco’s ResearchGate

Marco’s publications

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The complexity of implementing site-specific decision support tools

How scientists can help bridge the technology gap

In our latest We Measure the World podcast, we interview Oregon State University researcher Dalyn McCauley 

about her experience developing a site-specific decision support tool for on-farm management of crop damaging weather events—and techniques she used to help the grower implement changes for quality and yield improvements.

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Webinar Series: Irrigation of Controlled Environment Crops for Increased Quality and Yield

Part 1: Substrates and Water

Stop guessing. Start measuring.

When you irrigate in a greenhouse or growth chamber, you need to get the most out of your substrate so you can maximize the yield and quality of your product.

But if you’re lifting a pot to gauge how much water is in the substrate, it’s going to be difficult—if not impossible—to achieve your goals. To complicate matters, soil substrates and potting mixes are some of the most challenging media in which to get the water exactly right.

Without accurate measurements or the right measurements, you’ll be blind to what your plants are really experiencing. And that’s a problem, because irrigating incorrectly will reduce yield, derail the quality of your product, deprive the roots of oxygen, and increase the risk of disease.

Supercharge yield, quality—and profit

At METER, we’ve been measuring soil moisture for over 40 years. Join Dr. Gaylon Campbell, founder, soil physicist, and one of the world’s foremost authorities on soil, plant, and atmospheric measurements, for a series of irrigation webinars designed to help you correctly control your crop environment to achieve maximum results. In this 30-minute webinar, learn:

  • Why substrates hold water differently than normal soil
  • How the properties of different substrates and potting mixes compare
  • Why it’s difficult if not impossible to irrigate correctly without accurately measuring the amount of water in the substrate
  • The fundamentals of measuring soil moisture: specifically water content and electrical conductivity
  • How measuring soil moisture helps you get the most out of the substrate you choose, so you can improve your product
  • Easy tools you can use to measure soil water in a greenhouse or growth chamber to maximize yields and minimize inputs

Watch it now—>

The complete guide to irrigation management using soil moisture

Irrigation management: Why it’s easier than you think

Years ago, we received an irrigation management call from a couple of scientists, Drs. Bryan Hopkins and Neil Hansen, about the sports turfgrass they were growing in cooperation with the Certified Sports Field Managers at Brigham Young University (BYU) and their turfgrass research and education programs. They wanted to optimize performance through challenging situations, such as irrigation controller failure and more. Together, we began intensively examining the water in the root zone. 

BYU researchers are zeroing in on irrigation management best practices leading to better outcomes that are easier to achieve.

As we gathered irrigation and performance data over time, we discovered new critical best practices for managing irrigation in turfgrass and other crops, including measuring “soil water potential”. We combined soil water potential sensors with traditional soil water content sensors to reduce the effort it took to keep the grass performance high while saving water costs and reducing disease potential and poor aeration. We also reduced fertilization costs by minimizing leaching losses out of the root zone due to overwatering.

Supercharge yield, quality and profit in any crop with soil moisture-led irrigation management 

This article uses turfgrass and potatoes to show how to irrigate using both water potential and water content sensors, but these best practices apply to any type of crop grown by irrigation scientists, agronomists, crop consultants, outdoor growers, or greenhouse growers. By adding water potential sensors to his water content sensors, one Idaho potato grower cut his water use by 38%. This reduced his cost of water (pumping costs) per 100 lbs. of potatoes, saving him $13,000 in one year. But that’s not even the best part. His yield increased by 8% and he improved his crop quality—the rot he typically sees virtually disappeared.

What is soil water potential?

In simple terms, soil water potential is a measure of the energy state of water in the soil. It has a complicated scientific definition, but you don’t have to understand what soil water potential is to use it effectively. Think of it as a type of plant thermometer that indicates “plant comfort”—just as a human thermometer indicates human comfort (and health). Here’s an analogy that explains the concept of soil water potential in terms of optimizing irrigation. 

Read more—>

Hydraulic Conductivity: How Many Measurements Do You Need?

Two researchers show easier methods conform to standards

If you’re measuring saturated hydraulic conductivity with a double ring infiltrometer, you’re lucky if you can get two tests done in a day. For most inspectors, researchers, and geotechs—that’s just not feasible. Historically, double ring methods were the standard, however the industry is now more accepting of faster single ring methods with the caveat that enough locations are tested. But how many locations are enough?

Triple the tests you run in a day

Drs. Andrea Welker and Kristin Sample-Lord, researchers at Villanova University, are changing the way infiltration measurements are captured while keeping the standards of measurement high. They ran many infiltration tests with three types of infiltrometers with a variety of sizes and soil types. In this 30-minute webinar, they’ll discuss what they found to be the acceptable statistical mean for a single rain garden. Plus, they’ll reveal the pros and cons of each infiltrometer type and which ones were the most practical to use. Learn:

  • What types of sites were tested
  • How the spot measurements compared with infiltration rates over the whole rain garden
  • Pros and cons of each infiltrometer and how they compared for practicality and ease of use
  • What is an acceptable number of measurements for an accurate assessment

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Presenters

Dr. Andrea Welker, PE, F.ASCE, ENV SP, is a Professor of Civil and Environmental Engineering and the Associate Dean for Academic Affairs at Villanova University. She joined Villanova after obtaining her PhD at the University of Texas at Austin. Her research focuses on the geotechnical aspects of stormwater control measures (SCMs) and the effectiveness of SCMs at the site and watershed scale.

Dr. Kristin Sample-Lord, P.E., is an Assistant Professor of geotechnical and geoenvironmental engineering in the Civil and Environmental Engineering Department at Villanova University. She received her PhD and MS from Colorado State University. Her research includes measurement of flow and transport in soils, with specific focus on green infrastructure and hydraulic containment barriers.

Related article: How to measure soil hydraulic conductivity
Related article: Which grain size analysis method is right for you?

Just Released—New Environmental Measurement Podcast

Check out a new podcast made by contributors to the EnvironmentalBiophysics.org blog. We Measure the World is a podcast produced by scientists, for scientists. Application expert Holly Lane and data guru, Brad Newbold interview scientists from all types of disciplines who measure anything and everything about the world to make it better—and more sustainable.

Holly Lane interviews scientists from all types of disciplines

Hang with us to learn a lot and laugh a lot. Explore interesting environmental research trends, how scientists are solving research issues, and what tools are helping them better understand measurements across the entire soil-plant-atmosphere continuum.

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