Source: VIRGINIA POLYTECHNIC INSTITUTE submitted to NRP
QUANTIFIYING THE ROLE OF SOIL STRUCTURE IN THE TRANSPORT OF WATER, NUTRIENTS, AND POLLUTANTS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
1007839
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Oct 1, 2015
Project End Date
Sep 30, 2020
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
VIRGINIA POLYTECHNIC INSTITUTE
(N/A)
BLACKSBURG,VA 24061
Performing Department
School of Plant and Environmental Sciences
Non Technical Summary
Over the next half century, the human population is predicted to grow to more than 9.5 billion people. Providing adequate food and nutrition for everyone will require the "sustainable intensification" of agriculture, in which higher yields are produced from the same agricultural footprint, without causing negative impacts on local and global ecosystems. To this end, the United States Department of Agriculture (USDA) has been promoting management practices and strategies that encourage "healthy" soils, in which the physical, biological and chemical characteristics of the soil are preserved or enhanced. One result of managing lands using soil health principles (e.g, reduced tillage and the use of high-residue cover crops) has been increased soil aggregation, which has been associated with (among other attributes) greater numbers of large macropores. While this is generally considered a positive outcome, since macro-porosity often increases infiltration rates and reduces surface runoff and erosion, there is some question about whether macropores also allow water, nutrients and pollutants to preferentially move through the soil profile and bypass the root zone, in a process known as preferential flow. Preliminary evidence suggests that no-till soils may experience increased subsurface leaching of phosphorus and nitrogen relative to tilled soils, likely because tillage destroys many macropores. However, we still understand very little about the mechanisms, incidence, variability, and consequences of preferential flow related to soil management and structure. Thus, in this study I will examine the role of soil structure in the transport of water, nutrients, and pollutants.My specific objectives in this study are to:Quantify the infiltration capacity, soil water holding capacity, structure, and other physical and biological properties of five distinct soils managed under conventional tillage without high-residue multi-species cover crops, conventional tillage with high-residue multi-species cover crops, conservation tillage without high-residue multi-species cover crops, and conservation tillage with high-residue multi-species cover crops;Quantify nutrient cycling and loss under these four management practices;Innovate new instrumentation and methods that can be used to quantify soil macroporosity and structure;Develop a parameter that describes the "structural potential" of soils, which can be used by producers and agencies to better manage soils;Study the fate and transport of broad spectrum pesticides through unstructured and structured soils;Study the fate and transport of microbes through unstructured and structured soils from "leaky" sanitary pipes; andDevelop new quantitative soil health indicators/demonstration techniques that can be used in outreach and educational activities.The results of this study may ultimately be used to inform farming procedures, enhance sustainability efforts, protect water supplies, and alleviate environmental impacts of farming.
Animal Health Component
(N/A)
Research Effort Categories
Basic
80%
Applied
(N/A)
Developmental
20%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1020110205040%
1110210205020%
1120210205020%
1010110206120%
Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships; 112 - Watershed Protection and Management; 111 - Conservation and Efficient Use of Water; 101 - Appraisal of Soil Resources;

Subject Of Investigation
0110 - Soil; 0210 - Water resources;

Field Of Science
2050 - Hydrology; 2061 - Pedology;
Goals / Objectives
In this study, I aim to use a series of experiments to understand how soil structural pathways control the movement of water, nutrients, and pollutants. My specific objectives are:Quantify the infiltration capacity, soil water holding capacity, structure, and other physical and biological properties of five distinct soils managed under conventional tillage without high-residue multi-species cover crops, conventional tillage with high-residue multi-species cover crops, conservation tillage without high-residue multi-species cover crops, and conservation tillage with high-residue multi-species cover crops;Quantify nutrient cycling and loss under these four management practices;Innovate new instrumentation and methods that can be used to quantify soil macroporosity and structure;Develop a parameter that describes the "structural potential" of soils, which can be used by producers and agencies to better manage soils;Study the fate and transport of broad spectrum pesticides through unstructured and structured soils;Study the fate and transport of microbes through unstructured and structured soils from "leaky" sanitary pipes; andDevelop new quantitative soil health indicators/demonstration techniques that can be used in outreach and educational activities.
Project Methods
Task #1: Develop sites and install instrumentationI will develop five field sites across Virginia, located in Montgomery county (near the Virginia Tech campus), Franklin county (near the Ferrum college campus), Rockingham county, Nottaway county, and Accomack county. I will use a split-plot design, and develop 8 plots within actively managed fields. Each plot will be sub-divided into two replicates that will be independently instrumented and monitored.Task #2: Collect field measurements of soil physical, chemical and biological propertiesOver a three-year period, we will visit the site three times to measure plant residue, plant biomass, organic matter, nutrient uptake and biological respiration from each replicated subplot (n = 4).Task #3: Collect and analyze soil cores to determine soil propertiesDuring site visits we will collect replicated volumetric soil cores from 15, and 30 cm depths, to be analyzed for pH, P, K, total S, total and inorganic N, total S, water extractable N and C, microbial biomass, C and N, dissolved organic carbon (DOC), substrate-induced respiration (SIR) for active microbial biomass, catabolic response profile (CRP) for microbial functional capacity, 60 day C mineralization assays for bioavailable C, particulate organic matter (POM) and mineral C fractions, fungal:bacterial dominance, available water content, bulk density, cation exchange capacity (CEC); particle size and clay size distributions; swelling potential; water retention; and saturated hydraulic conductivity.Task #4: Innovate new instrumentation and methods to quantify soil macro-porosity and structureWe will develop a new "smart" tensiometer that is capable of rapidly and accurately changing the applied tension during an infiltration test. Once the instruments and methods are fully developed, we will collect infiltration measurements at our field sites every three months over a three year period. During each site visit, we will conduct four measurements per experimental treatment (one per replicate), for a total of sixteen infiltration tests per site per visit. By visiting the sites in different seasons (and likely different soil moisture conditions), we expect to capture the variation in pore sizes and pore size distributions that may occur throughout the year.Task #5: Develop a framework to add results to descriptions of NRCS-benchmark soilsWe will compile our results to develop an index relating to the "structural potential" of each soil type included in the study. This "structural potential" parameter will be continuous on the range of 0 to 1, and will incorporate the form, stability and resiliency of structure in a given soil.Task #6: Construct soil columns using an unstructured (sandy and clayey) soils and a structured clayey soilWe will construct columns using clayey and soil soils. We will use two different lengths (25 and 75 cm), so as to capture "leached" water at different depths and better understand pesticide dynamics within the crop root zone. The columns will be 20 cm in diameter, to help minimize edge effects. For the clayey soil, half of the columns will be filled with intact soil "monoliths", thus preserving soil structure, while the second half will be filled with sieved and repacked soil, so as to destroy any structure.Task #7: Perform pesticide leaching and physiochemical studyWe will sow TMX-coated corn seeds (1.25 mg/seed) into columns. In half of the columns, seeds will be allowed to sprout and grow for one month, while in the other columns seedlings will be pruned at emergence. We will collect leachate water that is produced during irrigation (up to nine events). After the one-month growing period, we will perform a final intensive irrigation on the columns until 1L of leachate is collected. Using our 75 cm columns, we will collect replicated samples of plant roots, leaves, and stems, and soil samples from the rhizosphere, from bulk soil outside of rhizosphere, and from 25, 50 and 75 cm depths. We will also quantify sorption/desorption dynamics and biotic and abiotic degradation rates using the USEPA's fate, transport and transformation test guidelines [USEPA., 2008].Finally, we will test for TMX concentrations in plant tissue, leachate water, and soil samples (486 samples in Year 1), using the LC/MS/MS analytical methods developed by a collaborator (Dr. Kang Xia)'s research group. Results from leaching, physiochemical, and uptake studies will be used for numerical modeling in Hydrus-1D [Simunek et al., 2005].Task #8: Perform plot-scale pesticide transport experimentWe will construct four replicated runoff plots at Kentland Farm. The plots will be 3 x 6 m, with 0.3 m tall metal barriers on the three "upslope" sides and a metal collection channel at the "downslope" side. We will measure surface runoff flowrates and will collect runoff water samples. In each plot we will install two sets of suction cup soil water samplers (at 20 and 50 cm depths) at 2 m and 4 m distances from the plot bottom. We will sow the plots with TMX-coated corn seeds (1.25 mg/seed). Throughout the growing season we will measure neonicotinoid concentrations in corn tissues and in runoff water samples. We will sample the soil water samplers after every major rain. In the case of insufficient natural rainfall, we will irrigate the plots at an agronomic rate. At the end of the growing season, we will analyze plant and soil samples for TMX concentrations.Task #9: Construct a soil mesocosm system to evaluate contaminant transport We will construct nine "variable-saturated" soil mesocosms that will allow us to perform microbial transport experiments.Task #10: Perform microbial transport studyWe will fill three mesocosms with an unstructured sandy soil, three with an unstructured (repacked) fine-textured clayey soil, and three with a structured (intact) clayey soil (approximately 0.38 m3 of soil per chamber). Water will be added until the system reaches steady-state. Lab-cultivated Escherichia coli (E. coli) bacteria will be added to the inlet water as a pulse (Experiment 1) and then as a continuous "injection" (Experiment 2). As a third experiment we will provide pulses of water mixed with research-grade E. coli, followed by multi-day drying periods. Water samples will be collected in the sampling ports and in the outfall and then analyzed for E. coli concentrations using standard culture-based methods. Water samples will be collected until the E. coli concentrations reach peak and/or steady-state values.Task #11: Develop new quantitative indicators that can be used to demonstrate and measure soil structure and healthWe will collect small intact soil monoliths from fields representing each of the four studied management practices (n = 3), and use them to visually demonstrate the differences in infiltration rates and soil microbial health by adding water mixed with resazurin. To better understand the relationship between resazurin and soil microbial activity, we will gather 32 soil samples from eight different soils (four replicates each). These soils will be sieved, packed into gas-tight test tubes, and then incubated with a glucose-resazurin-water solution for 4 hours. After the incubation period, the gas will be extracted and analyzed for CO2 concentration, and the soil will be analyzed for fluorescence using a fluorometric scanner. Regression analysis will be used to correlate resazurin fluorescence with microbial (CO2) respiration.Statistical analysisAll of these studies have been designed so that they can be analyzed using R or similar statistical software, to determine if treatment effects are significantly different from controls. We will analyze our collected data using Generalized Linear Models (GLMs) or Analysis of Variance (ANOVA) for defining statistically-significant treatments.

Progress 10/01/15 to 09/30/20

Outputs
Target Audience:Students: Two undergraduate students and five graduate students received training in data collection and curation, the scientific method and hypothesis testing, and scientific writing. Academic peers/researchers: Project results and findings were disseminated to others in the scientific community via peer-reviewed publications and conference presentations. Industry: The project results were presented to the wine-making industry via several conference and meeting presentations. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project led to numerous training and professional development activities: 1. Training of 9 graduate students, who have used this project framework to collect and analyze data related to their thesis and dissertation work. Five of the students graduated over the 5-year project period. 2. All of the graduate students practiced oral communication of technical results to academic audiences. Students were provided feedback by more senior scientists. 3. Involvement of 16 undergraduate students in undergraduate research opportunities. How have the results been disseminated to communities of interest?1. Project results were conveyed to scientific and producer audiences via presentations and publications. In total, we had 24 peer-reviewed journal articles published in association with this project (5-year total), with the target audience of other scientists, agricultural producers, and extension agents. 2. We gave 32 presentations associated with this project to scientific audiences. 3. We also developed and released three web-based data sources for agricultural producers and the public. The first is a "cover crop calculator" that uses a globally relevant meta-analysis to estimate mean changes in thirteen important soil health indicators due to the use of cover crops. The second is a database (SoilHealthDB) that compiles soil health-related measurements. The third is a database (SoilErosionDB) that compiles measurements of surface runoff and soil erosion from around the goal. 4. We held 10 workshops and field demonstration days with producers from across the state of Virginia. We also presented at a vineyard industry meeting. In total, more than 750 farmers and practitioners attended these events. 5. Project results were included in yearly presentations as part of the Virginia Governor's School of Agriculture. These presentations had a total audience of 500 different high school students over 5 years. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? 1. We published a total of 24 peer-reviewed journal articles that addressed project objectives. 2. We have finished and submitted for review the results of two studies examining transport of veterinary antibiotics and stable water isotopes through structured soils. 3. We have finished two studies that examine the fate and transport of neonicotinoid pesticides, with a specific focus on chemical uptake by different plant species and on the role of organic matter in retaining these compounds. 4. Three Ph.D. dissertations and two M.S. theses were completed through the project.

Publications

  • Type: Journal Articles Status: Published Year Published: 2020 Citation: McClanahan, S. J., W. H. Frame, R. D. Stewart and W. E. Thomason. 2020. Cotton yield and lint quality responses to nitrogen rate and placement in the humid southeast. Agronomy Journal. 112(5): 4276-4286. doi: 10.1002/agj2.20290.
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Fields, J., J. S. Owen, R. D. Stewart, and J. Heitman. 2020. Simulating Water Movement in a Peat and Pine Bark Substrate. Vadose Zone Journal. 19(1): e20031. doi: 10.1002/vzj2.20031.
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Bierer, A., R. O. Maguire, M. S. Strickland, R. D. Stewart, and W. E. Thomason. 2020. Evaluating dairy manure application method on soil health and nitrate. Journal of Soil and Water Conservation. 75(3). doi: 10.2489/jswc.2020.00074.
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Jian, J., X. Du, and R. D. Stewart. 2020. Quantifying cover crop effects on soil health and productivity. Data in Brief. 29: 105376. doi: 10.1016/j.dib.2020.105376.
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Jian, J., X. Du, M. S. Reiter, and R. D. Stewart. 2020. A meta-analysis of global cropland soil carbon changes due to cover cropping. Soil Biology and Biochemistry. 143: 107735. doi: 10.1016/j.soilbio.2020.107735.
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Jian, J., B. J. Lester, X. Du, M. S. Reiter, and R. D. Stewart. 2020. A calculator to quantify cover crop effects on soil health. Soil & Tillage Research. 199: 104575. doi: 10.1016/j.still.2020.104575.
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Concialdi P., H. Bhanderi, S. Di Prima, R. D. Stewart, M. R. Abou Najm, and L. Lassabatere. 2020. An open-source instrumentation package for intensive soil hydraulic characterization. Journal of Hydrology. 582: 124492. doi: 10.1016/j.jhydrol.2019.124492.
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Jian, J., X. Du, and R. D. Stewart. 2020. A database for global soil health assessment. Scientific Data. 7(16): 1-8. doi: 10.1038/s41597-020-0356-3.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Wolters, B., M. S. Reiter, M. L. Flessner, W. H. Frame, W. E. Thomason, S. C. Hodges, and R. D. Stewart. Invading rapeseed: Observations of cover crop species in mixtures becoming weeds. Presented at the 2019 ASA-CSSA-SSSA Annual Meeting. San Antonio, TX. November 13, 2019.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Wolters, B., M. S. Reiter, W. H. Frame, W. E. Thomason, and R. D. Stewart. Cover crop biomass and corn yields: 5 years of mixes. Presented at the 2019 ASA-CSSA-SSSA Annual Meeting. San Antonio, TX. November 12, 2019.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2020 Citation: Jaclyn C. Fiola, Ryan D. Stewart, Greg K. Evanylo, Tony K. Wolf. Characterizing the Contribution of Topsoil to Mid-Atlantic Grape Composition. 71st American Society for Enology & Viticulture National Conference.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Gyawali, A. J., R. D. Stewart, M. S. Strickland, W. E. Thomason, and S. C. Hodges. A multivariate approach to quantify responsiveness and consistency of soil health parameters. Presented at the 2019 ASA-CSSA-SSSA Annual Meeting. San Antonio, TX. November 11, 2019.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Radolinski, J. B., L. Pangle, J. Klaus, D. T. Scott, and R. D. Stewart. Simulating preferential flow in a two water worlds framework. Presented at the Black Forest Autumn School Conference: Water Ages in the Hydrological Cycle. Freudenstadt, Germany. October 30, 2019.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2020 Citation: Jaclyn C. Fiola, Ryan D. Stewart, Greg K. Evanylo, Tony K. Wolf (Invited presentation). Using A-horizon surveys to characterize grape quality in Mid-Atlantic vineyards. Northeast National Cooperative Soil Survey Virtual Conference. June 22, 2020.


Progress 10/01/18 to 09/30/19

Outputs
Target Audience:Students: Two undergraduate students, four graduate students, and one post-doctoral scholar received training in data collection and curation, the scientific method and hypothesis testing, and scientific writing. Academic peers/researchers: Project results and findings were disseminated to others in the scientific community via peer-reviewed publications and conference presentations. Agricultural producers, farmers, crop advisors: Research results were compiled to create a "cover crop calculator" for use by agricultural producers and crop advisors (https://soilhealth.spes.vt.edu/CoverCropCalculator.html). Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project led to several training and professional development activities: Training of one post-doctoral research associate: This project has allowed training of a post-doctoral scholar (J. Jian), who has transitioned into a research position at the Pacific Northwest National Laboratory. Training of 4 graduate students, who have used this project framework to collect and analyze data related to their thesis and dissertation work. Two of the students graduated during this reporting period. Three of the graduate students practiced oral communication of technical results to academic audiences. Students were provided feedback by more senior scientists. Involvement of 2 undergraduate students in undergraduate research opportunities. How have the results been disseminated to communities of interest? Project results were conveyed to scientific and producer audiences via presentations and publications. In total, we had 5 peer-reviewed journal articles published this year in association with this project, with the target audience of other scientists, agricultural producers, and extension agents. We gave 9 presentations associated with this project to scientific audiences. We also developed and released two web-based data sources for agricultural producers and the public. The first is a "cover crop calculator" that uses a globally relevant meta-analysis to estimate mean changes in thirteen important soil health indicators due to use of cover crops. The second is a database (SoilHealthDB) that compiles soil health-related measurements. What do you plan to do during the next reporting period to accomplish the goals? We will publish the results of our tillage/cover crop experiments. We will publish the results of our field and laboratory studies on transport of veterinary antibiotics. We will analyze results from a greenhouse study examining neonicotinoid pesticide uptake in different plant tissues. We will analyze results from a field study examining neonicotinoid pesticide uptake in soils with different organic matter composition and content. We will instrument and collect data from established field plots that evaluate the ability of cover crops and edge-of-field vegetated buffer strips to reduce neonicotinoid pesticide transport into ecosystems surrounding agricultural fields. We will continue to develop modeling frameworks to understand preferential flow processes in soils. We will continue the scientific training of two graduate students.

Impacts
What was accomplished under these goals? We have finished the final analysis of soil and plant samples from the objective focused on quantifying soil health. In all, we will have analyzed and quantified the physical and biological properties of 880 soil samples and 392 plant samples. We have developed a new theoretical framework to analyze preferential flow based on simple analytical descriptions and only four parameters, thus improving the ability to understand subsurface water movement processes. We have finished two studies that examine transport of veterinary antibiotics through structured field soils. We have finished two studies that examine fate and transport of neonicotinoid pesticides, with specific focus on chemical uptake by different plant species and on the role of organic matter in retaining these compounds. Two Ph.D. dissertations were produced by Ayush Gyawali and Jesse Radolinski.

Publications

  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Stewart, R. D., J. Jian, A. J. Gyawali, W. E. Thomason, B. D. Badgley, M. S. Reiter, and M. S. Strickland. 2018. What we talk about when we talk about soil health. Agricultural & Environmental Letters. 3(1): 180033. doi: 10.2134/ael2018.06.0033.
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Stewart, R. D. 2019. A generalized analytical solution for preferential infiltration and wetting. Vadose Zone Journal. 18(1): 1-10. doi: 10.2136/vzj2018.08.0148.
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Radolinski, J., J. Wu, K. Xia, W. C. Hession, and R. D. Stewart. 2019. Plants mediate precipitation-driven transport of a neonicotinoid pesticide. Chemosphere. 222: 445-452. doi: 10.1016/j.chemosphere.2019.01.150.
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Di Prima, S., M. Castellini, M. R. Abou Najm, R. D. Stewart, R. Angulo-Jaramillo, t. Winiarski, L. Lassabatere. 2019. Experimental assessment of a new comprehensive model for single ring infiltration data. Journal of Hydrology. 573: 937-951. doi: 10.1016/j.jhydrol.2019.03.077.
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Basset, C., M. R. Abou Najm, A. Ammar, R. D. Stewart, S. Hauswirth, and G. Saad. 2019. Physically based model for extracting dual-permeability parameters using non-Newtonian fluids. Vadose Zone Journal. doi: 10.2136/vzj2018.09.0172.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Bierer, A., R. O. Maguire, R. D. Stewart, W. E. Thomason, and M. S. Strickland. Modeling nitrate movement following manure injection using HYDRUS-2D. Presented at the 2018 American Society of Agronomy Annual Meeting. Baltimore, MD. November 6, 2018.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Wolters, B., M. S. Reiter, W. H. Frame, R. D. Stewart, S. C. Hodges, and M. L. Flessner. Soil quality improvement using diverse cover crop mixtures. Presented at the 2018 American Society of Agronomy Annual Meeting. Baltimore, MD. November 6, 2018.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Bierer, A., R. O. Maguire, M. S. Strickland, W. E. Thomason, and R. D. Stewart. Manure injection enhanced nitrogen recovery, but microorganisms unresponsive. Presented at the 2018 American Society of Agronomy Annual Meeting. Baltimore, MD. November 7, 2018.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Stewart, R. D., J. Jian, A. J. Gyawali, W. E. Thomason, B. D. Badgley, M. S. Reiter, and M. S. Strickland. Digging deeper into soil health. Presented at the 2018-2019 Soil Science Society of America International Soils Meeting. San Diego, CA. January 8, 2019.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Di Prima, S., M. Castellini, M. R. Abou Najm, R. D. Stewart, R. Angulo-Jaramillo, and L. Lassabatere. Testing a new comprehensive model for single ring infiltration data. Presented at the 2019 European Geophysical Union Annual Meeting, Vienna, Austria. April 10, 2019.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Stewart, R. D., J. Jian, *A. J. Gyawali, W. E. Thomason, B. D. Badgley, M. S. Reiter, and M. S. Strickland. What we talk about when we talk about soil health. Presented at the 2018 American Society of Agronomy Annual Meeting. Baltimore, MD. November 7, 2018.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Jian, J., and R. D. Stewart. A meta-analysis of soil carbon under cover crops. Presented at the 2018 American Geophysical Union Fall Meeting. Washington, DC. December 11, 2018.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Radolinski, J., H. Le, S. Hilaire, K. Xia, and R. D. Stewart. Preferential flow in the vadose zone: identifying solute vs media controls on contaminant transport. Presented at the 2018 American Geophysical Union Fall Meeting. Washington, DC. December 11, 2018.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Stewart, R. D. Predicting dynamic controls on preferential flow in soils. Presented at the 2018 American Geophysical Union Fall Meeting. Washington, DC. December 12, 2018.


Progress 10/01/17 to 09/30/18

Outputs
Target Audience:Scientists: My students and I reached technical audiences (i.e., other scientists and students) during presentations at regional, national, and international events, and via publications in peer-reviewed journals. Farmers: I worked with farmers via demonstration activities and presentations to inform their management practices. Extension agents: I worked with extension agents via presentations. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project led to several training and professional development activities: 1. Presentation to the Virginia Crop Production Association: "In-situ strategies for measuring and managing soil water content." This presentation allowed me to present to farmers various technologies and techniques for measuring and managing soil water content in their fields. 2. Training of one post-doctoral research associate: This project has allowed training of a post-doctoral scholar (J. Jian), who will now transition into a research position at the Pacific Northwest National Laboratory. 3. Training of 3 graduate students, who have used this project framework to collect and analyze data related to their thesis and dissertation work. 4. Involvement of 4 undergraduate students in undergraduate research opportunities. How have the results been disseminated to communities of interest?Project results were conveyed to scientific and producer audiences via presentations and publications. In total, we had 7 peer-reviewed journal articles published this year in association with this project, and gave 12 presentations associated with this project. What do you plan to do during the next reporting period to accomplish the goals?1. We will finish analyzing and publish the results of our tillage/cover crop experiments. 2. We will finish analyzing and publish the results of our field studies on transport of neonicotinoid pesticides and veterinary antibiotics. 3. We will conduct a soil column study to understand the influence of soil macroporosity and preferential flow on transport of water and emerging contaminants. 4. We will complete and analyze results from a greenhouse study examining neonicotinoid pesticide uptake in different plant species. 5. We will install instrumentation and experimental plots to quantify the ability of cover crops and edge-of-field vegetated buffer strips to reduce neonicotinoid pesticide transport into ecosystems surrounding agricultural fields. 6. We will work on modeling frameworks to understand preferential flow processes in soils.

Impacts
What was accomplished under these goals? 1. We have finished the third and final year of sample collection, and are nearing completion of analysis of these soil and plant samples. In all, we will have analyzed and quantified the physical and biological properties of 880 soil samples and 392 plant samples. 2. We have quantified Total N, Total C, Microbial Biomass N and C, and micro-nutrients on 500 soil samples collected from these experimental treatments. 3. We have developed a new method to consisently and accurately quantify soil aggregate stability, which is relevant to soil macroporosity and structure. 4. We have developed new theoretical frameworks to analyze water movement through homogenous and macroporous soils (e.g., soils with shrinkage cracks), improving the ability to understand subsurface water movement processes. 5. We have finished two studies that examine transport of emerging contaminants including neonicotinoid pesticides and veterinary antibiotics through structured field soils. 6. We have compiled data from over 500 soil health studies into a database that can be used to analyze soil health metrics across studies and systems. 7. We have created a soil health calculator for wintertime cover crops, that can be used for demonstration and outreach activities with producers and extension agents.

Publications

  • Type: Journal Articles Status: Published Year Published: 2018 Citation: McCourty, M., A.J. Gyawali, and R. D. Stewart. 2018. Of macropores and tillage: influence of biomass incorporation on cover crop decomposition and soil respiration. Soil Use and Management. doi: 10.1111/sum.12403.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Stewart, R. D. and M. R. Abou Najm. 2018. A comprehensive model for single ring infiltration 1: Influence of initial water content and soil hydraulic properties. Soil Science Society of America Journal. 82(3):548-557. doi: 10.2136/sssaj2017.09.0313.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Stewart, R. D. and M. R. Abou Najm. 2018. A comprehensive model for single ring infiltration 2: Estimating field-saturated hydraulic conductivity. Soil Science Society of America Journal. 82(3):558-567. doi: 10.2136/sssaj2017.09.0314.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Stewart, R. D. and M. R. Abou Najm. 2018. A brief overview of field measurements of soil cracks. Soil Science Society of America Journal. doi: 10.2136/sssaj2018.01.0044.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Stewart, R. D. 2018. A dynamic multi-domain Green and Ampt infiltration model for shrink-swell soils. Water Resources Research. doi: 10.1029/2018WR023297.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Bassett, C., M. R. Abou Najm, R. D. Stewart, S. Hauswirth, and G. Saad. Physically based models for extracting dual permeability parameters using non-Newtonian fluids. Presented at the 2018 European Geophysical Union Annual Meeting. Vienna, VA. April 10, 2018.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Orndorff, Z. W., S. K. Klopf, W. L. Daniels, R. D. Stewart, and R. Daniel. Initial evaluation of ripper and tillage methods on reclaimed heavy mineral mining sands. Presented at the 2018 American Society of Mining and Reclamation Annual Meeting. St. Louis, MO, June 5, 2018.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Gyawali, A. J., R. D. Stewart, M. S. Reiter, and W. E. Thomason. Quantifying dynamic soil health effects of tillage and cover crops. Presented at the 2018 Soil and Water Conservation Society Annual Meeting Conservation Innovation Grant Showcase. Albuquerque, NM, August 9, 2018.
  • Type: Other Status: Other Year Published: 2018 Citation: Presentation to the Virginia Crop Production Association. In-situ strategies for measuring and managing soil water content. Richmond, VA. January 16, 2018. (50 individuals served).
  • Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Gyawali, A. J., Z. Liu, and R. D. Stewart. Interpreting soil health dynamics via improved quantification of soil aggregate stability. Presented at the 2018 Soil and Water Conservation Society Annual Meeting. Albuquerque, NM, August 9, 2018.
  • Type: Journal Articles Status: Accepted Year Published: 2018 Citation: Gyawali, A.J. and R.D. Stewart. An improved method for quantifying soil aggregate stability. Soil Science Society of America Journal. Accepted October 20, 2018.


Progress 10/01/16 to 09/30/17

Outputs
Target Audience:Scientists: I reached scientist and student audiences during technical presentations at national meetings and both regional and international presentations, and via publications in peer-reviewed journals. Farmers: I worked with farmers via demonstration activities and presentations to inform their management practices. Extension agents: I worked with extension agents via presentations. State and federal agency employees: I gave several presentations and workshops that involved state and federal employees from environmental and agricultural-focused agencies. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project led to several training and professional development activities: 1. Cover Crop In-Service Training on the Eastern Shore of Virginia, which was hed on April 24 and 25, 2017. This training included visits to various experimental field plots and a 30-minute oral presentation, all focused on the role of cover cropping on soil health, soil properties, and nutrient cycling. The training was attended by 95 individuals, primarily representing NRCS, local Soil and Water Conservation Districts, and Virginia Cooperative Extension. This meeting was designed to provide information and recommendations for agents that work with producers throughout the state of Virginia (train the trainers). We particularly focused on ways in which agents can quantify, demonstrate and otherwise convey to farmers the ways in which management practices such as using cover crops improve soil health on short (1-3 year) time scales. 2. The Smith Creek Partnership Meeting in Harrisonburg, VA, which was held on Tuesday, August 29th, 2017. The 30-minute presentation was titled "Quantifying Soil Health" and focused on how infiltration capacity, soil water holding capacity, aggregate stability (structure), soil respiration, and crop yields are influenced by conservation agricultural practices (reduced tillage and multi-species cover crops). How have the results been disseminated to communities of interest?Project results were presented at several meetings (* indiciates student collaborator). Stewart, R. D., *B. Spencer, *C. van Skiver, and *A. J. Gyawali. Demonstrating soil biological health using a reactive color-changing dye. Presented at the 2017 NRCS Conservation Innovation Grant Showcase/Soil and Water Conservation Society Meeting. Madison, WI, July 30, 2017. *Gyawali, A. J. and R. D. Stewart. Quantifying time- and system-dependent dynamics of soil health. Presented at the 2017 NRCS Conservation Innovation Grant Showcase/Soil and Water Conservation Society Meeting. Madison, WI, July 30, 2017. Stewart, R. D., M. R. Abou Najm, D. E. Rupp, and J. S. Selker. Deciphering physical properties of preferential flowpaths using non-Newtonian fluids. Presented at the 2016 American Geophysical Union Fall Meeting. San Francisco, CA, December 15, 2016. *Spencer, B., *A. J. Gyawali, M. S. Strickland and R. D. Stewart. 2016. Measuring microbial respiration using a fluorometric dye. Presented at the 2016 Soil Science Society of America Annual Meeting. Phoenix, AZ, November 7, 2016. *Radolinski, J., *J. Wu, K. Xia and R. D. Stewart. 2016. Transport and fate of a neonicotinoid pesticide from seed coatings. Presented at the 2016 Soil Science Society of America Annual Meeting. Phoenix, AZ, November 7, 2016. *Bierer, A., R. O. Maguire, W. Thomason, M. Strickland, and R. D. Stewart. 2016. Effects of Dairy Slurry Injection on Soil Health and Nitrogen Cycling. Presented at the 2016 Soil Science Society of America Annual Meeting. Phoenix, AZ, November 9, 2016. What do you plan to do during the next reporting period to accomplish the goals?1. Finish the collection and analysis of soil and plant samples to quantify the effects of conservation management practices on soil physical, chemical and biological properties and nutrient cycling. 2. Publish results from our aggregate stability and microbially active color-changing dye experiments. 3. Publish remaining results from our study on pesticide transport through structured soils (2 manuscripts). 4. Work to develop a parameter that describes the "structural potential" of soils, which can be used by producers and agencies to better manage soils. 5. Continue work to develop new infiltration models that may be used to quantify soil physical properties, including macroporosity and structure.

Impacts
What was accomplished under these goals? 1. We have collected and analyzed an additional 100+ soil and plant samples for the project "Quantifying soil health", where soil physical, chemical and biological properties are being measured in response to soil health management practices. 2. We have developed a new method to rigorously quantify soil aggregate stability, which will be used to assess the effects of conservation agricultural practices on aggregate stability (which are related to the development and persistence of soil structure). 3. We have worked on using a color-changing flourometric dye to quantify microbial activity and soil health, with some progress towards developing a repeatable method. 4. We have collected preliminary data on using non-Newtonian (shear-thinning) fluids to quantify soil macroporosity and structure. These data were presented in December 2016, and experimentation continues. 5. We have finished a laboratory and field study on the transport of thiamethoxam (TMX) and clothiandin (CLO) through sandy and clayey soils. The results show that TMX and CLO are transported through all soils, but at the highest concentrations and fastest rates through structured clay soils. These results were published in 2017 (Radolinski et al., 2017, "Transport of a neonicotinoid pesticide, thiamethoxam, from artificial seed coatings", Science of the Total Environment), with two more manuscripts in preparation for publication in 2018.

Publications

  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Bierer, A. M., R. O. Maguire, M. S. Strickland, W. E. Thomason, and R. D. Stewart. 2017. Effects of dairy slurry injection on carbon and nitrogen cycling. Soil Science. doi: 10.1097/SS.0000000000000209.
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Radolinski, J. , *J. Wu, K. Xia, and R. D. Stewart. 2017. Transport of a neonicotinoid pesticide, thiamethoxam, from artificial seed coatings. Science of the Total Environment.
  • Type: Journal Articles Status: Under Review Year Published: 2018 Citation: Schulte, M. L., F. C. Wurster, K. Balentine, J. M. Varner, G. Speiran, W. M. Aust, R. D. Stewart, C. N. Jones and D. L. McLaughlin. Hydrologic Controls on Ecosystem Structure and Function at the Great Dismal Swamp. Wetlands.
  • Type: Journal Articles Status: Under Review Year Published: 2018 Citation: McCourty, M., A. J. Gyawali, and R. D. Stewart. Of tillage and macropores: influence of biomass incorporation on cover crop decomposition and soil respiration. Soil Use and Management.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2017 Citation: Gyawali, A. J. and R. D. Stewart. Quantifying time- and system-dependent dynamics of soil health. Presented at the 2017 NRCS Conservation Innovation Grant Showcase/Soil and Water Conservation Society Meeting. Madison, WI, July 30, 2017.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2017 Citation: Stewart, R. D., B. Spencer, C. van Skiver, and A. J. Gyawali. Demonstrating soil biological health using a reactive color-changing dye. Presented at the 2017 NRCS Conservation Innovation Grant Showcase/Soil and Water Conservation Society Meeting. Madison, WI, July 30, 2017.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Spencer, B., A. J. Gyawali, M. S. Strickland and R. D. Stewart. 2016. Measuring microbial respiration using a fluorometric dye. Presented at the 2016 Soil Science Society of America Annual Meeting. Phoenix, AZ, November 7, 2016.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Radolinski, J., J. Wu, K. Xia and R. D. Stewart. 2016. Transport and fate of a neonicotinoid pesticide from seed coatings. Presented at the 2016 Soil Science Society of America Annual Meeting. Phoenix, AZ, November 7, 2016.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Bierer, A., R. O. Maguire, W. Thomason, M. Strickland, and R. D. Stewart. 2016. Effects of Dairy Slurry Injection on Soil Health and Nitrogen Cycling. Presented at the 2016 Soil Science Society of America Annual Meeting. Phoenix, AZ, November 9, 2016.
  • Type: Conference Papers and Presentations Status: Accepted Year Published: 2016 Citation: Stewart, R. D., M. R. Abou Najm, D. E. Rupp, and J. S. Selker. Deciphering physical properties of preferential flowpaths using non-Newtonian fluids. Presented at the 2016 American Geophysical Union Fall Meeting. San Francisco, CA, December 15, 2016.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Blume, T., I. Heidb�chel, S. Simard, A. G�ntner, M. Weiler, and R. D. Stewart. Forest transpiration: Resolving species specific root water uptake patterns. Presented at the 2016 American Geophysical Union Fall Meeting. San Francisco, CA, December 14, 2016.


Progress 10/01/15 to 09/30/16

Outputs
Target Audience:My target audience during this reporting period includesfarmers, extension agents, and agricultural industry representatives. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Presentations/lectures. Provided training at Field Days/Tours to local farmers,dairymen, and Extension Agents. How have the results been disseminated to communities of interest?I presented a talk at the University of Wisconsin - Madison, on June 30th, 2016. This talk focused on the role of soil structure in water and contaminant movement, presenting findings from this project. In addition, we have helda number of demonstration days/activities throughout the summer at our various plots. On August 2nd, 2016, ~120 participants came to the field tour at the Southern Piedmont research center (Blackstone, VA). Our field plots were one of the featured stops on the tour, and we demonstrated visual differences in soil structure, aggregate stability, and differences in infiltration rates using repacked columns (Figure 4). The participants were engaged and had many questions about using reduced tillage practices in tobacco systems. The Ferrum field plots were featured during the 2016 Virginia No-Till Alliance (VANTAGE) Summer Field day, on August 5th, 2016. Around 25 local farmers and dairymen attended the showcase, where we again demonstrated soil health using visual assessments of soil structure, wet aggregate stability demonstrations, and infiltration tests. Finally, the Harrisonburg test plots were featured as part of the Smith Creek Partnership meeting on August 30th, 2016. This meeting was primarily attended by NRCS, City of Harrisonburg and DEQ personnel (approximately 20 participants in total). During the morning meeting we provided a lecture (30 minutes) on the project and its goals, and on the afternoon tour we again provided demonstrations of soil health differences between our treatments, focusing this time on a newly constructed portable rainfall/runoff simulator. Finally, the Harrisonburg test plots were featured as part of the Smith Creek Partnership meeting on August 30th, 2016. This meeting was primarily attended by NRCS, City of Harrisonburg and DEQ personnel (approximately 20 participants in total). During the morning meeting we provided a lecture (30 minutes) on the project and its goals, and on the afternoon tour we again provided demonstrations of soil health differences between our treatments, focusing this time on a newly constructed portable rainfall/runoff simulator. What do you plan to do during the next reporting period to accomplish the goals?We will collect and analyze another 100+ soil samples to quantify soil health. We will finalize our flourometric dye analysis to quantify microbial activity, with the goal of publishing a methods paper. We will publish our study on thiamethoxam (TMX) transport through soil columns, and a second publication for transport through field settings. We will install the equipment and begin data collection to quantify microbial transport through structured soils. We willpresent results at a minimum of two national conferences (ASA-CSA-SSSA annual meeting and AGU Fall meeting).

Impacts
What was accomplished under these goals? 1. We collected and analyzed 100+ soil and plant samples for the project "Quantifying soil health", where soil physical, chemical and biological properties are being measured in response to soil health management practices (reduced tillage and use of multi-species cover crops). 2. We have worked on using a color-changing flourometric dye to quantify microbial activity and soil health, with some progress towards developing a repeatable method. 3. We have collected preliminary data on using non-Newtonian (shear-thinning) fluids to quantify soil macroporosity and structure. These data will be presented in December 2016. 4. We have finished a laboratory and field study on the transport of thiamethoxam (TMX) through sandy and clayey soils. The results show that TMX is transported through all soils, but at the highest concentrations and fastestrates through structured clay soils. These results will be published in 2017 and 2018.

Publications

  • Type: Journal Articles Status: Under Review Year Published: 2016 Citation: Interpreting influence of initial water content and soil hydraulic properties on single ring infiltration. Journal of Hydrology and Hydromechanics.
  • Type: Conference Papers and Presentations Status: Accepted Year Published: 2016 Citation: Stewart, R. D., M. R. Abou Najm, D. E. Rupp and J. S. Selker. Modeling the effect of soil moisture on capillarity and infiltration. Presented at the European Geophysical Union Annual Meeting. Vienna, VA, April 18, 2016.
  • Type: Conference Papers and Presentations Status: Accepted Year Published: 2016 Citation: Abou Najm, M. R., N. Atallah, J. S. Selker, C. Roques, R. D. Stewart, D. E. Rupp, G. Saad, M. El-Fadel. 2016. Smart Fluids in Hydrology: Use of Non-Newtonian Fluids for Pore Structure Characterization. Presented at the European Geophysical Union Annual Meeting. Vienna, VA, April 18, 2016.
  • Type: Conference Papers and Presentations Status: Accepted Year Published: 2015 Citation: Blume, T., I. Heidbuechel, S. Hassler, S. Simard, A. Guntner, R. D. Stewart, and M. Weiler. 2015. Root Water Uptake and Soil Moisture Pattern Dynamics  Capturing Connections, Controls, and Casaulties. Presented at 2015 AGU Fall Meeting. San Francisco, CA. December 14, 2015.
  • Type: Conference Papers and Presentations Status: Accepted Year Published: 2015 Citation: Stewart, R. D. 2015. From Percolation to Infiltration: Using Fractal Models in Unsaturated Soils. Presented at the ASA-CSA-SSSA Annual Meeting. Minneapolis, MN. November 16, 2015.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2016 Citation: Stewart, R. D. Hydrogeochemical transport through macroporous soils. Presented at the University of Wisconsin, Madison WI. June 30, 2016.
  • Type: Other Status: Published Year Published: 2016 Citation: Stewart, R. D. 2016. Soil Health at the Nexus of Food, Energy, and Water. Crop Science Society of America Food-Energy-Water White Paper Database. https://www.crops.org/science-policy/white-papers/view/4.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2015 Citation: de la Mota, F., S. D. Day, J. S. Owen, and R. D. Stewart. 2015. Porous pavement effects on urban tree rooting depth and development. Presented at the International Society of Horticultural Science conference, Athens, Greece.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: de la Mota, F., R. D. Stewart, J. S. Owen, and S. D. Day. 2015. Trees in Pavement: Modelling water and heat fluxes in street tree plantings using HYDRUS. Presented at the American Society of Horticultural Science conference, Atlanta, GA.