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Posts from the ‘Soils’ Category

Smart orchard aims to install thousands of sensors for actionable insights

When big data is a problem

Orchard growers today live in an exciting time where environmental data are becoming inexpensive and abundant. But going from a data-poor to a data-rich environment has its challenges. Big data can be so overwhelming that growers struggle with how to turn that data into actionable insight.

In March, Innov8.ag began piloting a smart orchard project in collaboration with researchers from Washington State University & Oregon State University at Chiawana Orchards in Washington state.

One grower on the Washington Tree Fruit Research Commission recently commented that he uses no less than 19 data apps for making decisions. Steve Mantle, founder of innov8.ag, says, “It’s just overwhelming to a grower to consolidate all of this data together. We need to figure out how to help them with actual insights that impact either their yield quality / quantity—and just as importantly—their costs: particularly on labor, chemical/nutrients, and irrigation.”  That’s why in 2020, Mantle and his team approached the Tree Fruit Research Commission’s technology committee to see if they could bring their capabilities, ingesting data from many different data silos and sensor providers into one place, with the goal of providing actionable insights for growers in the apple orchard space. Thus, the idea of a “smart orchard” was born.

Turning big data into a solution

In March, Innov8.ag began piloting a smart orchard project in collaboration with researchers from Washington State University & Oregon State University at Chiawana Orchards in Washington state. Their goal was to “sensorize” an orchard from multiple hardware providers, bringing together growers, data, and researchers to create a sustainable, “smart” orchard with insights that impacted a grower’s bottom line. To do this they combined data from on-farm and off-farm, online and offline sources including satellites, drones, weather providers, telemetry from IoT devices such as soil moisture probes and leaf wetness sensors, and more.” Mantle adds, “We’re trying to see how the sensors at different price points and from different vendors compare against each other in terms of accuracy. But the biggest goal is to get more granularity around and prove the value in canopy, soil, and weather measurements. Then we tie that in with yield, quality, and profit.”

Installing sensors so that comparisons are valid

The smart orchard consists of 100 rows of Gala apple trees spaced out over two 20-acre blocks. A number of different sensor/instrumentation providers, including METER Group, have their sensors deployed at this smart orchard measuring parameters such as weather, irrigation, soil water and nutrients, chemicals, disease, pests, crop health, labor, and drone/satellite imagery. All these data are aggregated and organized on a regular basis to try and enable growers to better understand weather and climate change to make precise, informed decisions and better manage their water usage, labor, equipment, and chemical usage.

Smart Orchard team member and researcher, Harmony Liu, says one challenge they face is making sure the comparisons are valid. “We are careful to install the same sensor types at the same heights so we are making “apple-to-apple” comparisons.”

Liu says in addition to sensing, they collect soil samples every week throughout the season and send them out to two different labs for nutrient testing so they can look at how that data compares with the soil nutrient sensors. They sample at five different locations at three different depths to match the sensors. She adds, “We have the dendrometer, soil nutrient data, soil moisture data, and canopy data all being collected within the same zone. It’s part of our intent to show this data all connecting with each other.” The team also measures irrigation line pressure with a sensor as opposed to using an irrigation switch. Liu says, “We want to know what the pressure signature is as everything turns on and activates so we can understand what that signature looks like and start to identify when there are abnormalities in how the irrigation system fills.” Additionally, they’re using METER NDVI and PRI sensors as well as a pyranometer for ground truthing the drone imagery that they’re doing at a 7 centimeters per pixel resolution.

The goal is understanding in-canopy weather and how to work with institutions on adapting models for disease, pests, and ultimately informing spray management.

Data cleanup is time-consuming

Liu says getting the smart orchard up and running was not without its challenges. “The first challenge was gaining access to some of the data from grower owned instruments because those instruments are not all grouped together.” Liu says that challenge made data cleanup time consuming, but they worked their way through it. She adds, “Overall, having this density of data is difficult because it’s a lot to wade through. But at the same time, it’s been really helpful. Data has been reliable coming in across the board.”

In-farm vs. outside-farm measurements

Liu says one thing they are interested in is accurately measuring temperature and humidity within the orchard because these parameters are critical for apple disease modeling. She says, “When people are modeling disease, they take the inputs from weather forecasts into the disease model for risk calculations. But there are some differences in environmental conditions inside vs. outside the orchard where evapotranspiration will cause temperatures in the canopy to be cooler compared to outside-farm temperatures while the vapor pressure is higher. So that’s one thing we use METER group instruments for. We have outside-orchard,  above-orchard, and in-canopy ATMOS 41 weather stations and ATMOS 14 temperature and relative humidity sensors. We use these to compare the temperature and relative humidity difference. By using an instrument from the same provider, we eliminate the systematic bias vs. if we were to compare temp and RH from different providers. We also set up a vertical profile by installing sensors on the same pole at different heights and could see how the temperature and humidity changed across height for that location.”

Register for the smart orchard project live webinar with innov8.ag this Thursday, Jan.14th at 4pm PST.

Future smart orchard goals

Mantle says their most important goal is understanding in-canopy weather and how they can work with WSU and other institutions on adapting models for disease, pests, and ultimately informing spray management. Liu adds, “We also want to understand data comparison and unification. We want to bring together soil moisture measurements like volumetric water content and data from the METER TEROS 21 matric potential sensor. What we found is that, although they’re looking at soil moisture from different perspectives, unifying the two measurements will be critical for people working on irrigation scheduling.” The team also plans on working with WSU professors to create an evapotranspiration map that blends together some of the sensor telemetry and the view from a drone.

See the webinar

Want to learn more? METER soil physicist, Dr. Colin Campbell and Washington State University soil scientist Dr. Dave Brown discuss the smart orchard project in a METER Group webinar.

View more METER crops webinars—>

Soil Electrical Conductivity: Managing Salts for Sustained High Yields

Managing salts: Why you should care more

Mismanagement of salt applied during irrigation ultimately reduces production—drastically in many cases. Irrigating incorrectly also increases water cost and the energy used to apply it.

Understanding the salt balance in the soil and knowing the leaching fraction, or the amount of extra irrigation water that must be applied to maintain acceptable root zone salinity is critical to every irrigation manager’s success. Yet monitoring soil salinity is often poorly understood.

Measure EC for consistently high crop yields

In this webinar, world-renowned soil physicist Dr. Gaylon Campbell teaches the fundamentals of measuring soil electrical conductivity (EC) and how to use a tool that few people think about—but is absolutely essential for maintaining crop yield and profit. Learn:

  • The sources of salt in irrigated agriculture
  • How and why salt affects plants
  • How salt in soil is measured
  • How common measurements are related to the amount of salt in soil
  • How salt affects various plant species
  • How to perform the calculations needed to know how much water to apply for a given water quality

Register now—>

Presenter

Dr. Gaylon S. Campbell has been a research scientist and engineer at METER for over 20 years, following nearly 30 years on faculty at Washington State University. Dr. Campbell’s first experience with environmental measurement came in the lab of Sterling Taylor at Utah State University making water potential measurements to understand plant water status.

Dr. Campbell is one of the world’s foremost authorities on physical measurements in the soil-plant-atmosphere continuum. His book written with Dr. John Norman on Environmental Biophysics provides a critical foundation for anyone interested in understanding the physics of the natural world. Dr. Campbell has written three books, over 100 refereed journal articles and book chapters, and has several patents.

Snapdragons and soil moisture sensors

Charles Bauers has been a hydroponic snapdragon grower for 17 years. He knows—in detail—how to produce a good snap. But five years ago, he needed a better way to measure water.

Soil sensors optimize irrigation for improved quality and profit

“We had no quantitative way to measure water. That was the limiting factor for me,” he explains. Other inputs, like fertilizer, were quantifiable, but Bauers still depended on “gut feel” for watering, and no matter how quickly he reacted to changes in the crop, he couldn’t consistently produce grade-one snapdragons.

He wanted a scale, a “recipe of numbers” that would let him produce a good crop all the time in all sections of the greenhouse.

“There are always areas that seem to produce good quality flowers, and then there are areas that are a bit more of a challenge. I installed METER soil moisture sensors in the good areas and the stressed areas and compared the two. Then I worked my stressed areas up to the same numbers.”

The TEROS 12 is well-suited for greenhouse applications

Snapdragons are very sensitive to moisture stress. “It’s a ten-week crop. If you don’t get the moisture right in the first two weeks, you can compromise that crop.”

Identifying irrigation set points

The soil moisture sensors made a huge difference in Bauers’s ability to get the moisture right.  “They give me, targeted set points that I can shoot for all the time, and if I hit the targeted set point, I know I’m going to have good quality snaps, barring any other type of stress.

Grade-one snapdragons are worth 40% more than grade twos, and the difference between the two is created by “incipient stress—water stress that you can’t measure with your fingers. You can’t see it, you can’t feel it, it’s stress at the root. There’s a difference between a 28% vwc [volumetric water content] and a 23% vwc. It’s only 5%, but one produces grade ones and one produces grade twos.”

Empowered with real-time information

Moisture sensors gave Bauers real-time information that helped him get the watering right in every part of the greenhouse.  “I became more consistent because I had a number to go at. Because we’re a hydroponic crop, we see the effects real quick, and I’d say ‘I just have to add a little more water here.’ But [before the sensors,] invariably we had areas that were stressed because you really never knew when you had enough water on that crop. With sensors, you can consistently put the right amount of water on all the time.”

Soil sensors helped identify and prevent irrigation problems

Bauers quickly became adept at using sensors to address his irrigation challenges. The sensors showed him where his irrigation system was broken or underperforming, helped him identify problems like a root growing into a drip tube, or an unplugged dripper. But as the sensors became part of his routine, he was surprised to discover a new opportunity.

“Besides giving me the real-time information, the sensors gave me the ability to look at trends…over a week or a month and be proactive if we started moving away from our set point. We could add more water, set shorter run times, or just make some changes in the irrigation system to get more in line with the set points. That was one of my biggest surprises, how well we were able to be proactive toward environmental changes using the trending of the charts. That was a bonus.”

Reducing production and labor costs

After five years of daily monitoring, Bauers is now ready to go to an even higher level. “The next huge area we see sensors in is as big, or bigger, than the actual growing of the plant itself. We’re going to use these sensors to guide us as we strip out all excess production costs, and that’s happening today. As an example, over the next five months we’ll be trimming our substrate use by 85%. Not only do we save on materials, but if you have 85% less substrate to work with or move, you reduce labor costs.”

In fact, the sensors have become an integral part of how Bauers does business. I asked him how he would feel if he lost them. “My gosh,” he said, “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.”

Learn more

Watch: How to improve irrigation scheduling using soil moisture—>

See all irrigation webinars—>

Webinar: Why Water Content Can’t Tell You Everything You Need to Know

Water content can leave you in the dark

Everybody measures soil water content because it’s easy. But if you’re only measuring water content, you may be blind to what your plants are really experiencing.

Soil moisture is more complex than estimating how much water is used by vegetation and how much needs to be replaced. If you’re thinking about it that way, you’re only seeing half the picture. You’re assuming you know what the right level of water should be—and that’s extremely difficult using only a water content sensor.

Get it right every time

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

TEROS 21 water potential sensor

In this 30-minute webinar, METER soil physicist, Dr. Colin Campbell, discusses how and why scientists combine both types of sensors for more accurate insights. Discover:

  • Why the “right water level” is different for every soil type
  • Why soil surveys aren’t sufficient to type your soil for full and refill points
  • Why you can’t know what a water content “percentage” means to growing plants
  • How assumptions made when only measuring water content can reduce crop yield and quality
  • Water potential fundamentals
  • How water potential sensors measure “plant comfort” like a thermometer
  • Why water potential is the only accurate way to measure drought stress
  • Why visual cues happen too late to prevent plant-water problems
  • Case studies that show why both water content and water potential are necessary to understand the condition of soil water in your experiment or crop

WATCH IT NOW—>

Presenter

Dr. Colin Campbell has been a research scientist at METER for 20 years following his Ph.D. at Texas A&M University in Soil Physics. He is currently serving as Vice President of METER Environment. He is also adjunct faculty with the Dept. of Crop and Soil Sciences at Washington State University where he co-teaches Environmental Biophysics, a class he took over from his father, Gaylon, nearly 20 years ago. Dr. Campbell’s early research focused on field-scale measurements of CO2 and water vapor flux but has shifted toward moisture and heat flow instrumentation for the soil-plant-atmosphere continuum.

How to Use Plant-Water Relations and Atmospheric Demand for Simplified Water Management

Going by soil moisture data alone?

Soil moisture data are useful, but they can’t tell you everything. Other strategies for growers and researchers, like plant and weather monitoring, can inform water management decisions.

Researcher using the SC-1 leaf porometer to measure stomatal conductance
Researcher using the SC-1 leaf porometer to measure stomatal conductance

In this webinar, world-renowned soil physicist, Dr. Gaylon Campbell shares his newest insights and explores options for water management beyond soil moisture. Learn the why and how of scheduling irrigation using plant or atmospheric measurements. Understand canopy temperature and its role in detecting water stress in crops. Plus, discover when plant water information is necessary and which measurement(s) to use. Find out:

  • Why the Penman-Monteith equation, with the FAO 56 procedures, gives a solid, physics-based method for determining potential evapotranspiration of a crop
  • How the ATMOS 41 microenvironment monitor combined with the ZL6 logger and ZENTRA Cloud give easy access to crop ET data
  • How assimilate partitioning can be controlled by manipulating plant water potential using appropriate irrigation strategies
  • Why combining monitoring soil water potential with deficit irrigation based on ET estimates provide an efficient and precise method for controlled water stress management
  • And more…

REGISTER NOW—>

Presenter

Dr. Gaylon S. Campbell has been a research scientist and engineer at METER for over 20 years, following nearly 30 years on faculty at Washington State University. Dr. Campbell’s first experience with environmental measurement came in the lab of Sterling Taylor at Utah State University making water potential measurements to understand plant water status.

Dr. Campbell is one of the world’s foremost authorities on physical measurements in the soil-plant-atmosphere continuum. His book written with Dr. John Norman on Environmental Biophysics provides a critical foundation for anyone interested in understanding the physics of the natural world. Dr. Campbell has written three books, over 100 refereed journal articles and book chapters, and has several patents.

Soil Hydraulic Properties—8 Ways You Can Unknowingly Compromise Your Data

Avoid costly surprises

Measuring soil hydraulic properties like hydraulic conductivity and soil water retention curves is difficult to do correctly. Measurements are affected by spatial variability, land use, sample prep, and more.

Image of a research using the SATURO infiltrometer in the field
Leo Rivera teaches soil hydraulic properties measurement best practices

Getting the right number is like building a house of cards. If one thing goes wrong—you wind up with measurements that don’t truly represent field conditions. Once your data are skewed in the wrong direction, your predictions are off, and erroneous recommendations or decisions could end up costing you a ton of time and money. 

Get the right numbers—every time

For 10 years, METER research scientist, Leo Rivera, has helped thousands of customers make saturated and unsaturated hydraulic conductivity measurements and retention curves to accurately understand their unique soil hydraulic properties. In this 30-minute webinar, he’ll explain common mistakes to avoid and best practices that will save you time, increase your accuracy, and prevent problems that could reduce the quality of your data. Learn:

  • Sample collection best practices
  • Where to make your measurements
  • How many measurements you need
  • Field mapping tools
  • How to get more out of your instruments
  • How to use the LABROS suite to fully characterize soils (i.e., full retention curves and hydraulic conductivity curves)
  • Best practices for measuring field hydraulic conductivity using SATURO

Watch it now—>

Water potential sensors improve peanuts, cotton, and corn irrigation

Ron Sorensen, a researcher at the National Peanut Research Laboratory in Georgia, is working to help small-scale peanut, corn, and cotton farmers in Georgia optimize irrigation.

Image of a cotton field in southern U.S

Cotton field in southern U.S.

Shallow subsurface drip irrigation is a very economical alternative for these farmers. “If you can put in a pivot, most of those are already in,” says Sorensen. What he’s working with are “small, irregularly shaped fields that go around swamps or in trees or backwoods where they might have 10 to 15 acres that used to be an old farmstead.”

Sorensen helps revitalize these old farmsteads by revamping old wells and plowing in drip tape. In many cases, farmers can have water running the same day they start the project.

Subsurface drip offers significant benefits to these farmers. “What I like about drip is that…I can fill up the soil profile, and I know I can fill it up. With the pivot, I’m putting out water today, and I may be coming back two days later and doing it again,” Sorensen says. “And I’m putting all this water on the leaves, creating the incidence for disease… With cotton, you can actually wash the pollen out of the flowers, and you won’t set a boule. There you’re losing yield. Whereas with drip, you can turn it on, you’re never wetting leaves, you’re getting full pollination… I’m an advocate for drip on small irrigated fields.

Image of a tractor plowing a field

“Irrigating down here [using diesel-powered irrigation pumps] is upwards of $11 an acre any time the farmer turns it on. So if he can wait a day, he’s saved that irrigation.”

“I love pivots on big fields, but we have to manage the water correctly. Farmers are starting to see that. We can save the farmer money, save him time, save him labor. Those…are all side benefits of irrigating correctly,” says Sorensen.

As farmers begin to see the benefits of efficient irrigation, Sorensen’s challenge is to help them know when to water and how much water to put on.

Sorensen is at the end of his third year gathering data with METER water potential sensors. He buries sensors at 10- and 20-inch depths in three separate plots, then irrigates when the average water potential reaches -40, -60, and -80 kPa respectively.

“We started in corn, because we know it has a shallow root system, and when you don’t irrigate corn, you don’t get any yield.” Initially, they allowed the profile to dry out to -120 kPa, but “we discovered it doesn’t work. We weren’t ever irrigating, and we had really bad yields. -120 was much too dry, and we cut back to -40, -60, and -80.”

The researchers used water potential readings with moisture release curves to determine how much water to add to bring the profile to field capacity.

Image of a researcher using a TEROS 21 sensor

METER TEROS 21 water potential sensor

They found that allowing the soil to dry to -60 allowed them to save water without impacting yields in corn. Cotton and peanuts are a different—and more complex—story.  “Both cotton and peanut, if you don’t get any rain or water, they just hunker down, and when you do get a rainstorm, they flourish. When the rainfall comes at a funny time, it changes everything,” Sorensen explains.

Take this year, for example. Until the first of June, Sorensen’s plots got very little rain. Then from June to the end of July, he got 24 – 26 inches. “All the differences between our plots are just gone. Irrigated is the same as the non-irrigated because by the time we started to irrigate, it started raining.”

Despite this setback, Sorensen is confident that the data will ultimately help produce a reliable irrigation tool for farmers. His goal is to add a drip irrigation module to Irrigator Pro, a computer program currently used by pivot irrigators.

He is working with several farmers who already use sensors in conjunction with the Irrigator Pro model. “They can use the computer model as a guess to get close, and then they can use a sensor to really get down to the exact day,” he says. And in Georgia, the exact day can matter quite a bit.

“What it comes down to is: Do I need to turn the pump on or not?” he explains. “Irrigating down here [using diesel-powered irrigation pumps] is upwards of $11 an acre any time the farmer turns it on. So if he can wait a day, and if we have one of these gulf storms come through, and the farmer gets 3/4 inch of rain, he’s saved that irrigation.

“And if you can save two, three, maybe four irrigations a year, we’re conserving water, we’re making the farmer more sustainable, and he can take that money and reinvest it into his farm, or into his children, or wherever he wants to put it. And that makes it so we have food on the table, clothes on our backs, cotton, corn, or peanuts, we’ve got food to eat.”

Discover METER water potential sensors

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

Soil Moisture—6 Common Oversights That Might Be Killing Your Accuracy

Your decisions are only as good as your data

If you rely on soil moisture data to make decisions, understand treatment effects, or make predictions, then you need that data to be accurate and reliable. But even one small oversight, such as poor installation, can compromise accuracy by up to +/-10%. How can you ensure your data represent what’s really happening at your site?

Image of a researcher digging an installation site for a sensor
Chris Chambers discusses how people unknowingly compromise their soil moisture data.

Best practices you need to know

Over the past 10 years, METER soil moisture expert Chris Chambers has pretty much seen it all. In this 30-minute webinar, he’ll discuss 6 common ways people unknowingly compromise their data and important best practices for higher-quality data that won’t cause you future headaches. Learn:

  • Are you choosing the right type of sensor or measurement for your particular needs?
  • Are you sampling in the right place?
  • Why you must understand your soil type
  • How to choose the right number of sensors to deal with variability
  • At what depths you should install sensors 
  • Common installation mistakes and best practices
  • Soil-specific calibration considerations
  • How cable management can make or break a study
  • Factors impacting soil moisture you should always record as metadata
  • Choosing the right data management platform for your unique application

Watch it now—>

How to interpret soil moisture data

Surprises that leave you stumped

Soil moisture data analysis is often straightforward, but it can leave you scratching your head with more questions than answers. There’s no substitute for a little experience when looking at surprising soil moisture behavior. 

Image of orange, yellow, and white flowers in a green house
Join Dr. Colin Campbell April 21st, 9am PDT as he looks at problematic and surprising soil moisture data.

Understand what’s happening at your site

METER soil scientist, Dr. Colin Campbell has spent nearly 20 years looking at problematic and surprising soil moisture data. In this 30-minute webinar, he discusses what to expect in different soil, environmental, and site situations and how to interpret that data effectively. Learn about:

  • Telltale sensor behavior in different soil types (coarse vs. fine, clay vs. sand)
  • Possible causes of smaller than expected changes in water content 
  • Factors that may cause unexpected jumps and drops in the data
  • What happens to dielectric sensors when soil freezes and other odd phenomena
  • Surprising situations and how to interpret them
  • Undiagnosed problems that affect plant-available water or water movement
  • Why sensors in the same field or same profile don’t agree
  • Problems you might see in surface installations

Watch it now

Degradation of soil-applied herbicides under limited irrigation

Soil-applied herbicides are important for controlling weeds in many crops because they offer a broadened control spectrum and chemical diversity. But if soil-applied herbicides persist in the soil too long, there is risk for damage to susceptible rotational crops in succeeding years. Since herbicide degradation in the soil is highly dependent on water, imminent needs to reduce agricultural water use in the future could lead to limited herbicide degradation and a greater risk for carryover.

Image of a sunflower in a sunflower field facing the sun
Some crops don’t have a wide variety of post-emergent herbicide options, so growers are dependent on soil-applied herbicides for weed control.

Recently Daniel Adamson and a research team at the University of Wyoming, under the guidance of Dr. Gustavo Sbatella, investigated the effects of soil-applied herbicides under limited irrigation conditions. They wanted to understand how limited irrigation affects the efficacy and carryover of soil-applied herbicides in Wyoming’s irrigated crop rotations. A two-part field study was undertaken by applying four soil-applied herbicides to dry beans and four soil-applied herbicides to corn. 

Soil microbe activity matters

Describing his research site, Adamson says, “Wyoming is not a huge farming state but there’s a pocket of farm ground near the Powell/Cody area with a unique rotation. The main crop is sugar beets, and they also grow dry, edible beans, sunflowers and malt barley. Some of these crops don’t have a wide variety of post-emergent herbicide options, so growers are dependent on soil-applied herbicides for weed control. However, they need to balance weed control with timely dissipation so sensitive rotational crops won’t be injured.

Adamson says that soil-applied herbicides tend to be fairly long-lived in the soil, which is advantageous for weed control. Importantly, the herbicides dissipate through degradation by soil microbes, and soil microbes are highly influenced by how much water is in soil. When the soil is moist and warm, microbes are more active, and they degrade the herbicides faster. Thus, his team hypothesized that if future climate change effects led to limited availability of surface water for irrigation, these herbicides may not degrade as quickly and possibly injure crops planted successionally.

Assessing herbicide damage

During the first year, the research team applied three irrigation treatments to each crop: 100%, 85%, and 70% of crop evapotranspiration. Both crops and soil moisture were monitored using METER data loggers and soil moisture sensors. Adamson recalls, “The sensors were our means of tracking what was happening in the soil in terms of volumetric water content. Some of the areas were chronically dry, so the sensors enabled us to confirm that the treatments were applied correctly and should theoretically affect how the herbicides were performing. The volumetric soil water content of the three irrigation treatments averaged 24%, 18%, and 16% throughout the growing season, and crop yield decreased as irrigation was reduced.” 

Over the course of the second year, the team collected soil samples at regular intervals following herbicide application. They analyzed the samples for herbicide level and used them to perform a greenhouse bioassay to determine crop response to residual herbicide. Also during the second year, crop response was evaluated in the field when sugar beet, sunflower, and dry bean or corn was planted over the original plots and assessed for herbicide damage.

Crops planted in a field assessed for herbicide damage
The results of the experiment were surprising.

Hurdles and challenges

Adamson said timing was the major difficulty in terms of applying irrigation treatments. He said, “There were no differences in irrigation timing for the various treatments. The way we irrigated was not representative of a typical deficit irrigation strategy because we were tied to a sprinkler with other projects on it. So we irrigated based on when the full water treatment would normally be irrigated. Other treatments had smaller nozzles so the amount of water was physically reduced.”

Adamson said they also weren’t prepared to track how some of the herbicides would behave in the soil. “Some of the herbicides degrade into metabolites that are phytotoxic in the soil, and it was hard to analyze for all molecules that were plant active. So that was challenging.”

Surprising results

Adamson said the results of the experiment were surprising. He says, “It was a good result for growers because we found there were no differences in the fields, statistically or visually, between how the herbicides carried over in the really dry soil versus the normally irrigated soil. So that was surprising, but from a practical standpoint for farmers, it was important information. They now know if they do have to start applying less water, it isn’t something to be overly concerned about.”

More research is needed

Adamson says more work is needed in this area of research. He adds, “There’s a tremendous amount of information within the weed science community about what herbicides do in the soil and things that influence that. But relatively few studies look at changing irrigation rates in a practical sense. A lot of the current studies are done in rain-fed systems where the amount of rain changes (i.e., a normal year vs. a drought year). In irrigated systems, you might reduce the amount of water, but it’s not a drastic reduction like a rain-fed system might experience. There’s not a huge amount of research looking at how different irrigation rates affect herbicide management, so I do think it would be worth exploring in the future.”

Download the researcher’s complete guide to soil moisture—>

Download the researcher’s complete guide to water potential—>