Grant A. Harris fellowship (2015 recipients)


  • 2015 recipients

  • Andrew Green

    Andrew Green – Kansas State University
    A repeatable screening of wheat and its wild relatives for moisture stress tolerance

    Previous studies have identified “drought tolerant” accessions of the wild wheat species Aegilops geniculata Roth and common wheat (Triticum aestivum, L.) in controlled environments. Controlled environment screening is necessary to grow unadapted germplasm and to isolate moisture stress from additional stresses in the field. 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. Monitoring water potential in the soil and the plant is the only quantifiable way to impose a consistent and repeatable treatment. With the development of a soil-moisture retention curve for a homogenous growth media, the moisture treatment could be maintained at a biologically relevant matric potential, and corresponding plant water potentials could be recorded. METER EC-5 volumetric water content sensors, METER MPS-6 matric potential sensors, as well as column tensiometers are being used to monitor soil moisture conditions in a greenhouse experiment using 182 cm tall polyvinyl chloride (PVC) growth tubes using the homogenous growth media, Profile Greens Grade. Previously characterized wheat varieties are being grown in a pilot study, and an advanced collection of Aegilops geniculata will be screened in the larger system. Measurements will be taken for days to 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. This data could be a quantifiable way to classify genotypes for response to moisture stress.

    • Awarded 13 MPS-6 water potential & temperature sensors and 26 EC-5 soil moisture sensors
  • Benjamin Carr

    Benjamin Carr – Iowa State University
    Soil thermal and hydraulic properties for dynamic bulk density during wetting and drying cycles after tillage

    Surface soil is a complex, dynamic interface which dictates mass and energy transfer between land and atmosphere and determines water flow and partitioning in the hydrological cycle. Its properties are considered dynamic because they are controlled in part by soil water content, which can change quickly with wetting events or slowly over sustained periods of drainage, plant uptake, and evaporative drying. A common assumption in hydrologic studies considering dynamic soil surface properties is that soil bulk density is static. Natural processes (e.g., freeze- thaw) and anthropogenic modifications (e.g., tillage) impact soil bulk density. Therefore, if transient bulk density can be quantified, the impact on soil thermal and hydraulic properties can be measured. In order to continually monitor the changes in soil thermal and hydraulic properties in a tilled field, I propose using thermo-TDR sensors to determine in situ soil water content and thermal properties, latent and sensible heat fluxes, in addition to assessing the state of soil bulk density and porosity. I request water potential and water content sensors to enable the determination of field water retention characteristics and hydraulic conductivities.

    • Awarded 18 MPS-6 water potential & temperature sensors, nine EC-5 soil moisture sensors
  • Rachel Rubin
    Rachel Rubin – Northern Arizona University
    Do soil microbes influence plant response to heat waves?

    Heat waves and drought disrupt ecosystems and are increasing in frequency and intensity, yet they receive much less research attention than long-term, gradual warming. The acute effects of these events are profound, reducing aboveground productivity by 30% across the European continent in 2003. Although understudied, heat waves and drought likely produce legacy effects mediated by the soil microbial community. I will manipulate rhizosphere communities in vivo and evaluate the performance of native grasses transplanted under a field-applied heat wave, an increasing scenario in the southwest and a growing challenge within ecological restoration. I expect that heat waves will alter soil microbial community structure, reducing bacterial abundance but preserving fungal abundance. Second, I expect that growing grasses with heat-waved inoculum will “prime” plants for heat tolerance, due to acclimation of rhizosphere microbes. METER instrumentation will shed new insight onto the abiotic factors associated with heat waves, including associated impacts to microbial-available and plant-available water.

    • Awarded eight MPS-6 water potential & temperature sensors, eight GS1 soil moisture sensors, four Em50 data loggers

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  • Stephanie Fulton

    Stephanie Fulton – University of Georgia
    Continuous monitoring to determine how engineering hydraulic flowpaths maintain water quality and quantity during surface coal mining and valley fill operations

    Researchers have found that salinity levels—as measured by conductivity, a proxy for total dissolved solids (TDS) loadings—are the strongest indicator of stream degradation below surface coal mining and valley fill (SCM/VF) operations throughout central Appalachia. We are currently investigating the effectiveness of an experimental “hydrologic isolation” mine reclamation method designed to maintain water quality and quantity downstream from SCM/VF operations by minimizing groundwater contact with high salt-producing overburden. The identification and characterization of source water contributions to streamflow using conductivity will help us determine how the hydrologic isolation method affects the nature and duration of surface water-groundwater interactions and increase our understanding of the dominant hydrologic flowpaths contributing to streamflow in mined watersheds. Continuous monitoring data provides much greater temporal resolution than quarterly or monthly monitoring data and is critical to understanding how conductivity varies seasonally and with varying antecedent rainfall conditions. The goal of our study is to evaluate how hydrologic engineering practices that control the movement of groundwater flow through SCM/VF mine sites can impact streamflow generation mechanisms and water chemistry. Our research objectives include evaluating the effect of hydrologic engineering on reducing solute loadings to and conductivity levels in receiving streams and the mechanisms controlling streamflow generation processes and water chemistry below SCM/VF.

    The collection of continuous hydrologic and water chemistry data using METER’s Em50R remote data logging system coupled with CTD-10 sensors will help us understand the hydrologic dynamics at a remote SCM/VF site located in Magoffin County in the eastern coal fields of Kentucky.

    • Awarded four CTD-10 sensors, three Em50 data loggers, one data station
  • Benjamin Wallen
    Benjamin Wallen – Colorado School of Mines
    Experimental and modeling investigation of shallow subsurface processes influenced by land-atmosphere interactions/applications to landmine detection

    One of the most prolific, worldwide environmental hazards are antipersonnel landmines. The success of technologies to detect landmines is dependent on many factors to include the landmine’s physical composition and the length of time in the ground from emplacement. However, one commonly overlooked area is the environmental conditions in which the landmine is placed. By gaining a greater understanding of the environmental conditions in the vicinity of a landmine, we can better calibrate numerical models used to develop algorithms that interface with different detection technologies. Characterizing the environmental conditions in the vicinity of a landmine emplacement location is the focus of this research. Numerous numerical and analytical models to predict the physical properties of the shallow subsurface have been developed. The fundamental knowledge of the character of the terrain and the dynamic processes that alter the properties of the terrain are key to these models. The goal of this research is to improve our understanding of the non-isothermal, multi-phase flow processes of water, water vapor, and air in the shallow subsurface in order to better predict the spatial and temporal distribution of soil moisture.  This will ultimately provide more spatially refined soil moisture and temperature distribution predictions, enabling better understanding to model, simulate, and predict the environmental conditions that are most dynamic to mine detection performance.

    • Awarded five VP-3 temperature & relative humidity sensors, ten ECT air temperature sensors, ten EC-5 soil moisture sensors

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  • Henry Sintim
    Henry Sintim – Washington State University
    Biodegradable plastic mulch: degradation and impacts on soil quality

    Application of conventional plastic mulch (CPM) in agriculture is a common practice by most specialty crop producers worldwide. It offers the benefits of increased water-use efficiency plus weed, pest, and disease control. This subsequently improves crop yield and quality. Nonetheless, producers need to retrieve and safely dispose CPM after usage, which increases the total production cost.  Substituting CPM with biodegradable plastic mulch films (BPM) will alleviate disposal needs. However, potential impact on agricultural soil ecosystems needs to be assessed before BPM adoption. The objectives of my research are to

    1. Examine degradation of different BPM types over time
    2. Assess BPM’s effects on soil quality
    3. Evaluate leaching of BPM degradation products through soil

    I will assess soil quality using the USDA Soil Quality Test Kit available from Gempler. Since soil temperature and moisture content are important parameters that govern chemical reaction rates and microbial activity and are likely to vary among the different BPM treatments, they will be monitored using METER’s 5TM soil moisture and temperature sensors installed at 10 cm and 20 cm depths. I will also install METER’s G3 drain gauges at a 30 cm depth to collect leachate samples for analysis of BPM particulates. The degradation of BPM over time will be examined by assessing the material properties and also measuring the particle size and surface area via photography, digitization of the photographs, and image analysis using the Image J software.

    • Awarded one G3 drain gauge, six 5TM soil moisture & temperature sensors, one Em50G remote data logger
  • Shuyang Zhen
    Shuyang Zhen – University of Georgia
    Using normalized difference vegetation index (NDVI) as a proxy for plant size in predictive water use models to facilitate precision irrigation

    Precise irrigation based on plant water needs not only allows for optimal plant growth but also conserves water and alleviates environmental pollution from fertilizer and pesticide runoff. A thorough understanding of crop-specific water requirements is essential for more efficient irrigation. However, plant water use changes on a daily basis, driven by variations in environmental conditions as well as changes in plant size over time. While environmental conditions are relatively easy to measure, direct determination of plant size is often destructive and time consuming. Remote sensing of vegetation indices, such as the normalized difference vegetation index (NDVI), provides a continuous and non-destructive method to estimate canopy size for use in water use models. My current work using METER NDVI sensors will develop quantitative models that predict daily water use (DWU) of bedding plant species based on environmental factors and NDVI, a proxy for plant size. The goal is to use NDVI in place of ‘crop coefficients’ which are commonly used in agronomic applications.

    Our preliminary data show that NDVI is highly correlated with plant growth, and a multiple linear regression model developed using only radiation and NDVI explained over 85% of variations in DWU. The inclusion of additional environmental variables or reference evapotranspiration can refine these models. Therefore, we will carry out one additional study for model validation purposes and scale up through collaboration with commercial growers and develop study sites in nurseries.

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  • Jeb Fields
    Jeb Fields – Virginia Tech
    Water conservation in container-sized production via engineering soilless substrates for increase available water

    There is a growing realization that water is a finite resource of which agriculture, including container crop production, is a leading consumer. Nearly two-thirds of all ornamental crops produced in the U.S. are grown in containers utilizing soilless culture, in which upwards of 20,000 gallons of water per acre per day can be applied to yield marketable crops. Soilless substrates have been developed to provide ample air-filled porosity, ensuring sufficient drainage, thus allowing growers to water in excess to avoid risks associated with water stress. However, with a looming water crisis more water-sustainable production practices are needed.

    My research involves manipulating soilless substrate hydrophysical properties in an effort to better understand how water moves through and interacts with substrate pores and particles. Furthermore, this research will determine how variations in hydrophysical properties of soilless substrates affect the growth and development of containerized crops. Altering conventionally used soilless substrates to have optimized hydraulic properties will allow for increased water distribution and subsequent availability in containerized substrates.  Enabling water to mobilize more readily within a container will provide roots access to higher percentages of water held within the substrate and thus increase available water. With higher percentages of water being available, growers can yield more biomass while applying less water, thus using water more efficiently during production.

    The overarching goal of my research is to reduce water consumption in container production by engineering soilless substrates utilizing traditional components (e.g., Sphagnum peat and bark) without altering other production practices or investing in new technologies.

    • Awarded 1 WP4C dew point water potential meter
  • Mitchell Hunter
    Mitchell Hunter – Penn State University
    Canopy sensing of drought stress in pursuit of ecological climate adaption

    I will deploy METER Spectral Reflectance Sensors (SRS) and Infrared Radiometers (IR) to characterize the impacts of cover cropping on maize drought stress responses.  The instruments will enable measurement of maize canopy development, light use efficiency, and canopy temperature.  I will use rain exclusion shelters to impose drought stress on maize following five cover crop treatments.  The METER instruments will be installed on two mobile observatory units.  Each unit will include SRS sensors calibrated to read the normalized differential vegetation index (NDVI) and the photochemical reflectance index (PRI), with reference sensors pointed at the sky, as well as one IR.

    This mobile system will build on the current set of repeated ecophysiological methods used in this study.  These include: maize height, leaf area index (LAI; METER AccuPAR LP-80), stomatal conductance (METER SC-1), pre-dawn leaf water potential (PMS Instruments Pressure Chamber), and leaf greenness (Konica Minolta SPAD).

    NDVI readings will provide an earlier, more accurate, and more repeatable indicator of canopy development than LAI.  Following canopy closure, paired PRI-NDVI readings will provide insight into light use efficiency; IR readings of canopy temperature will provide an indicator of moisture stress.  Together, they will enable season-long measurement of maize stress.

    These instruments will improve the temporal resolution and mechanistic specificity of my field study, enable methods development, and help validate a crop model.  More broadly, this will enhance understanding of how ecological management practices (cover crops) can aid adaptation to projected future conditions under climate change (drought).

  • Lance Stott
    Lance Stott – Utah State University
    Techniques for achieving precision water stress in orchards

    High value tree fruit crops require careful irrigation management to conserve water resources.  Moderate water stress of these crops results in higher fruit sugar content, but a reliable indicator of tree water status is required before precision water stress can be used.  Measurements of soil moisture are unreliable because of the deep and extensive root systems of trees.  Pressure bomb measurements of stem water potential are reliable, but are labor intensive and cannot be automated.  Infrared measurements of leaf-air temperature differences are only partly effective.  Using frequency domain reflectometry soil moisture sensors inserted into the trunks of fruit trees promises to be an effective method of continuously monitoring tree water status.  Successfully relating trunk water content measurements with pressure bomb measurements and leaf to air temperature differences could provide a reliable indicator of tree water status.  This method could then be used to precisely time irrigation and/or automate precision irrigation systems in orchards throughout the world, resulting in potential water use savings, improved crop quality and less nutrient leaching and runoff.

    • Awarded 13 MPS-6 water potential & temperature sensors and 26 EC-5 soil moisture sensors

    Read more about soil moisture sensors used in tree stems

  • Clinton Steketee
    Clinton Steketee – University of Georgia
    Improving drought tolerance in soybean with the use of microclimate stations to monitor environment conditions and predict water stress for accurate phenotyping

    With climate change, it is expected that events such as drought will be more frequent and extreme in the future. Drought stress is a significant issue threatening the agricultural productivity of soybean (Glycine max L. Merrill) and can reduce yields by as much as 40 percent. Varieties with improved tolerance are needed to sustain and increase soybean production to feed a continuously growing world human population.

    Drought tolerance research progress in soybean has been limited to date, mainly because drought conditions are unpredictable both spatially and temporally. To make selection of drought tolerant lines easier and more predictable, knowledge of field environmental conditions is critical. Given this information, improved drought tolerance screening techniques can be used to collect accurate phenotypic data and identify drought tolerant genotypes. Molecular markers and other genomic tools developed with this phenotypic data are most reliable if the data is collected at times when differences among soybean lines evaluated accurately reflects the true phenotype of a particular genotype.

    To conduct a drought tolerance study, we selected 211 soybean lines to form the panel for a genome-wide association study to identify genomic regions responsible for drought tolerance and to develop new genomic tools by evaluating drought-related traits in the field at two locations over two years. These 211 lines come from 30 countries and were selected from known geographical areas of the world prone to drought—areas with low annual precipitation and newly developed soybean lines with enhanced drought-related traits. METER microclimate stations equipped with sensors to monitor environmental conditions at the field research sites will greatly help us predict water stress and determine ideal time periods for phenotyping these drought-related traits.

    • Honorable Mention: awarded two Microenvironment Monitors, two Em50G remote data loggers, two GS-1 soil moisture sensors, DataTrac 3 software
  • Katherine East
    Katherine East – Washington State University
    Developing a life-cycle degree day model for Meloidogyne halpa (Northern Root Knot Nematode) to improve Washington wine grape management state

    Root-knot nematodes are endoparasitic organisms that infest plant roots and form galls that disrupt normal translocation of sugars and water. Declines in vigor in older vineyards and poor establishment or death of young vines in replant situations have been attributed to nematodes. The northern root-knot nematode, Meloidogyne hapla, is the most prevalent species of root-knot nematode found in Washington wine grape vineyards. Knowing when the different life stages of M. hapla are present in the soil will allow growers to target those stages that are more susceptible to management intervention.

    We know that the rate of M. hapla development and infectivity is most dependent on soil temperature and moisture. As such, we foresee the ability to develop a life-cycle model based on the temperature proxy of growing degree days. Over the next two years, I will intensively sample both soil and roots for life stages of M. hapla in two vineyards, and compare that to various environmental parameters such as air-based growing degree-days, soil temperature, and soil moisture. I plan on collecting the soil parameters using the METER 5TM soil moisture and temperature sensors and Em50 data loggers.

    • Honorable Mention: awarded four Em50 data loggers, 12 5TM sensors, 12 MPS-6 sensors