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Posts from the ‘Greenhouse’ Category

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.

Remote Data

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.”

Remote Data

“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.

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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.


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.”


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.

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Screening for Drought Tolerance

Screening for drought tolerance in wheat species is harder than it seems.  Many greenhouse drought screenings suffer from confounding issues such as soil type and the resulting soil moisture content, bulk density, and genetic differences for traits like root mass, rooting depth, and plant size. In addition, because it’s so hard to isolate drought stress, some scientists think finding a repeatable screening method is next to impossible. However, a recent pilot study done by researcher Andrew Green may prove them wrong.

drought tolerance

Automatic Irrigation Setup

The Quest for Repeatability

Green says, “There have been attempts before of intensively studying drought stress, but it’s hard to isolate drought stress from heat, diseases, and other things.”  Green and his advisors, Dr. Gerard Kluitenberg and Dr. Allan Fritz, think monitoring water potential in the soil is the only quantifiable way to impose a consistent and repeatable treatment. With the development of a soil-moisture retention curve for a homogeneous growth media, they feel the moisture treatment could be maintained in order to isolate drought stress.  Green says, “Our goal is to develop a repeatable screening system that will allow us to be confident that what we’re seeing is an actual drought response before the work of integrating those genes takes place, since that’s a very long and tedious process.”

Why Hasn’t This Been Done Before?

Andrew Green, as a plant breeder, thinks the problem lies in the fact that most geneticists aren’t soil scientists. He says, “In past experiments, the most sophisticated drought screening was to grow the plants up to a certain point, stop watering them, and see which ones lived the longest. There’s never been a collaborative approach where physiologists and soil scientists have been involved.  So researchers have imposed this harsh, biologically irrelevant stress where it’s basically been an attrition study.” Green says he hopes in his research to use the soil as a feedback mechanism to maintain a stress level that mimics what exists in nature.

drought tolerance

Data Acquisition Cabinet setup for Green’s expanded experiment.

The Pilot Study

Green used volumetric water content sensors, matric potential sensors, as well as column tensiometers to monitor soil moisture conditions in a greenhouse experiment using 182 cm tall polyvinyl chloride (PVC) growth tubes and homogenous growth media. Measurements were taken four times a day to determine volumetric water content, soil water potential, senescence, biomass, shoot, root ratio, rooting traits, yield components, leaf water potential, leaf relative water content, and other physiological observations between moisture limited and control treatments.  

Soil Media:  Advantages and Disadvantages

To solve the problem of differing soil types, Andrew and his team chose a homogeneous soil amendment media called Profile Greens Grade, which has been extensively studied for use in space and other applications.  Green says, “It’s a very porous material with a large particle size.  It’s a great growth media because at the end of the experiment you can separate the roots of the plant from the soil media, and those roots can be measured, imaged, and studied in conjunction with the data that is collected.”   Green adds, however, that working with soil media isn’t perfect: there have been hydraulic conductivity issues, and the media must be closely monitored.

What’s Unique About this Study?

Green believes that because the substrate was very specific and his water content and water potential sensors were co-located, it allowed him to determine if all of his moisture release curves were consistent.  He says, “We try to pack these columns to a uniform bulk density and keep an eye on things when we’re watering, hoping it’s going to stay consistent at every depth.  So far it’s been working pretty well: the water content and the water potential are repeatable in the different columns.”

drought tolerance

Entire Irrigation setup for the expanded study.

Plans for the Future

Green’s pilot study was completed in the spring, and he’s getting ready for the expanded version of the project:  a replicated trial with wild relatives of wheat. He’s hoping to use soil moisture sensors to make automatic irrigation decisions: i.e. the water potential of the columns will activate twelve solenoid valves which will disperse water to keep the materials in their target stress zone, or ideal water potential.

The Ultimate Goal

The ultimate goal of Green’s research is to breed wild species of wheat into productive forms that can be used as farmer-grown varieties. He is optimistic about the results of his pilot study.  He says, “Based on the very small unreplicated data that we have so far, I think it is going to be possible to develop a repeatable method to screen these materials.  With the data that we’re seeing now, and the information that we’re capturing about what’s going on below ground, I think being able to hold these things in a biologically relevant stress zone is going to be possible.”

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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.”

dual measurements

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.

dual measurements

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.

dual measurements

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).

dual measurements

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.  

dual measurements

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.

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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.

nursery growers

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.”

nursery growers

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.

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