Progress 05/01/22 to 10/31/22
Outputs
Target Audience:Environmental research community (both academic and non-academic; governmental and non-governmental). Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The project provided training opportunities to several graduate students.One Ph.D. and three M.S. level students contributed to this project. Students were trained to conduct laboratory experiments,perform hydrological modeling, and quantify various macropore characteristics in soil cores. Research results were presentedat various conferences, and peer-reviewed publications were prepared. How have the results been disseminated to communities of interest?The research results were presented at various conferences (e.g., American Society of Agricultural and Biological Engineers International Meeting, Alabama Water Resources Conference). Additionally, peer-reviewed articles were published in the journals to share research results with a broader audience. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
The study employed X-ray computed tomography scanning, laboratory-based rainfall simulations, and solute transport modeling to highlight that loss of phosphorus (P) via preferential flow pathways can be significant and should be considered in developing best management practices. The results from X-ray CT scanning revealed that land use type, season, grazing, and topographic location within a field could impact soil macropore characteristics. Further, an important finding of the project was that soil macropores in the soil profile could enhance the leaching of colloidal-facilitated P, which is typically not considered in most studies. Land use type, manure type (dairy vs. swine vs. poultry), and soil macropore characteristics influenced the migration of P in different forms in the soil profile. The soil columns (150 mm diameter and 500 mm depth) investigated in this study were excavated from agricultural fields in Alabama and Wisconsin. The soil cores were scanned using a medical GE LightSpeed VCT 64 Slice CT scanner (GE Healthcare, Chicago, IL) installed in the Bailey Small Animal Teaching Hospital at the Auburn University College of Veterinary Medicine. In Wisconsin, soil cores were scanned using a Discovery CT750 HD medical X-ray computed tomography scanner (GE Healthcare, Chicago, IL). In soil cores collected from Alabama, we observed variability in macropore characteristics among the different slope positions and depths. This implies that soils' hydraulic properties vary as a function of topographical location. Additionally, the results of this project showed that macropore characteristics could change seasonally. The macropore characteristics varied seasonally mainly because of the wetting and drying cycles that promoted the formation of smaller macropores. In row cropping systems, the cores retrieved from conventional tillage corn fields had significantly higher surface area density, length density, interconnectivity, and network density than the soil cores collected from the no-till corn field. Therefore, because of the presence of macropores, contaminants may quickly bypass the soil profile and reach groundwater or nearby surface water through subsurface flows. For rainfall simulation experiments, poultry litter was applied at a rate of 10 Mg/ha, while swine and dairy manure were applied based on total nitrogen requirements for tall fescue. Leachate samples were analyzed for different forms of P (e.g., total P (TP), dissolved reactive P (DRP), total dissolved P (TDP), and colloidal P). The colloidal particles were separated using filtration and ultracentrifugation processes. Bromide tracer was used to assess the existence of preferential flow from all columns. HYDRUS-1D was used to simulate the bromide and DRP leaching trends from all columns. The rainfall simulation results indicated that the application of all three types of manure had a significant effect on P leaching losses, with differences in manure properties being the main reason for different behaviors of P leaching from the soil columns. The flow-weighted mean concentrations of total P ranged from 6.22 to 12.18 mg/L, 0.95 to 1.42 mg/L, and 0.29 to 1.1 mg/L in leachate for columns treated with poultry, swine, and dairy manure, respectively. In some columns, colloidal P contributed 43% of the total P leaching. The flow-weighted mean P leaching losses from all columns exceeded 0.1 mg L-1 (USEPA level of concern). In Wisconsin, we observed clear peaks in turbidity, dissolved P, and colloidal P that appeared close to the breakthrough of bromide.A good agreement (R2: 0.96 to 0.99) between observed and predicted bromide breakthrough curves could be achieved with the dual-porosity model using HYDRUS 1D. The bromide and P leaching trends indicated the existence of preferential flow. For the HYDRUS modeling component, the input soil hydraulic parameters (saturated hydraulic conductivity and porosity) were measured in the lab. The dual porosity with a two-site sorption model was used to identify the DRP transport and reaction parameters through calibration from the DRP breakthrough curves (BTCs) in a two-step process. In the first step, the solute transport parameters were estimated using the mobile-immobile physical nonequilibrium model to fit the bromide BTC in the inverse mode. Two parameters, dispersivity, and immobile water content were predicted simultaneously using the BTCs of bromide by inverse solution in HYDRUS. Further, the estimated parameters were used as input to run the DRP simulations in the inverse mode. Some of the reaction parameters required by the HYDRUS-1D model for DRP simulations were derived in the laboratory experiments, such as the Freundlich adsorption coefficients and bulk density, and four parameters (Frac, Frac_M, Omega, and Alpha) were optimized. A significant amount of immobile water content was present in all columns, indicating the existence of macropore flow. The model simulated the DRP concentrations adequately. The results showed that the average dispersivity was higher in the treatment columns as compared to the control columns, suggesting that the manure application altered the soil physical properties so that the solute dispersion increased. The DRP BTCs were asymmetrical and exhibited tailing, indicating non-equilibrium sorption. The overall application of HYDRUS-1D in simulating preferential transport of DRP in undisturbed soil columns was effectively described by the implemented non-equilibrium solute transport model (dual porosity model with two-site sorption in the mobile zone). Overall results provide clear evidence of a greater risk of P leaching from columns with macropore networks. Therefore, the characterization of different P forms (dissolved, colloidal, and total P) is required to develop management practices to minimize P loss.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Malhotra, K., J. Lamba, T.R. Way, S. Budhathoki, and P. Srivastava. Impact of land use and tillage practice on preferential transport of phosphorus. American Society of Agricultural and Biological Engineers Annual International Meeting, Houston, Texas, July 17-20, 2022.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Malhotra, K., J. Lamba, T.R. Way, S. Budhathoki, and P. Srivastava. Subsurface transport of phosphorus in pasture soils: Influence of preferential flow paths. American Society of Agricultural and Biological Engineers Annual International Meeting, Houston, Texas, July 17-20, 2022.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Preetika, K., S. Budhathoki, K.Malhotra*, J.Lamba, and T.Way. 2022. Biopore Quantification based on macropores shape in pastures. [Poster]. Auburn Research Student Symposium, Auburn University, Alabama.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Preetika, K., J. Lamba, V. Sandhu*, T. R. Way, and Kip Balkcom. 2022. Effect of Cover Crop and Tillage Practice on Pore Properties. 2022 ASA-CSSA-SSSA International Annual Meeting, November 6-9, Baltimore, MD.
|
Progress 05/01/18 to 10/31/22
Outputs
Target Audience:Environmental research community (both academic and non-academic; governmental and non-governmental). Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The project provided training opportunities to several graduate students. One Ph.D. and three M.S. level students contributed to this project. Students were trained to conduct laboratory experiments, perform hydrological modeling, and quantify various macropore characteristics in soil cores. Research results were presented at various conferences, and peer-reviewed publications were prepared. How have the results been disseminated to communities of interest?The research results were presented at various conferences (e.g., American Society of Agricultural and Biological Engineers International Meeting, Alabama Water Resources Conference). Additionally, peer-reviewed articles were published in the journals to share research results with a broader audience. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
The study employed X-ray computed tomography scanning, laboratory-based rainfall simulations, and solute transport modeling to highlight that loss of phosphorus (P) via preferential flow pathways can be significant and should be considered in developing best management practices. The results from X-ray CT scanning revealed that land use type, season, grazing, and topographic location within a field could impact soil macropore characteristics. Further, an important finding of the project was that soil macropores in the soil profile could enhance the leaching of colloidal-facilitated P, which is typically not considered in most studies. Land use type, manure type (dairy vs. swine vs. poultry), and soil macropore characteristics influenced the migration of P in different forms in the soil profile. The soil columns (150 mm diameter and 500 mm depth) investigated in this study were excavated from agricultural fields in Alabama and Wisconsin. The soil cores were scanned using a medical GE LightSpeed VCT 64 Slice CT scanner (GE Healthcare, Chicago, IL) installed in the Bailey Small Animal Teaching Hospital at the Auburn University College of Veterinary Medicine. In Wisconsin, soil cores were scanned using a Discovery CT750 HD medical X-ray computed tomography scanner (GE Healthcare, Chicago, IL). In soil cores collected from Alabama, we observed variability in macropore characteristics among the different slope positions and depths. This implies that soils' hydraulic properties vary as a function of topographical location. Additionally, the results of this project showed that macropore characteristics could change seasonally. The macropore characteristics varied seasonally mainly because of the wetting and drying cycles that promoted the formation of smaller macropores. In row cropping systems, the cores retrieved from conventional tillage corn fields had significantly higher surface area density, length density, interconnectivity, and network density than the soil cores collected from the no-till corn field. Therefore, because of the presence of macropores, contaminants may quickly bypass the soil profile and reach groundwater or nearby surface water through subsurface flows. For rainfall simulation experiments, poultry litter was applied at a rate of 10 Mg/ha, while swine and dairy manure were applied based on total nitrogen requirements for tall fescue. Leachate samples were analyzed for different forms of P (e.g., total P (TP), dissolved reactive P (DRP), total dissolved P (TDP), and colloidal P). The colloidal particles were separated using filtration and ultracentrifugation processes. Bromide tracer was used to assess the existence of preferential flow from all columns. HYDRUS-1D was used to simulate the bromide and DRP leaching trends from all columns. The rainfall simulation results indicated that the application of all three types of manure had a significant effect on P leaching losses, with differences in manure properties being the main reason for different behaviors of P leaching from the soil columns. The flow-weighted mean concentrations of total P ranged from 6.22 to 12.18 mg/L, 0.95 to 1.42 mg/L, and 0.29 to 1.1 mg/L in leachate for columns treated with poultry, swine, and dairy manure, respectively. In some columns, colloidal P contributed 43% of the total P leaching. The flow-weighted mean P leaching losses from all columns exceeded 0.1 mg L-1 (USEPA level of concern). In Wisconsin, we observed clear peaks in turbidity, dissolved P, and colloidal P that appeared close to the breakthrough of bromide. A good agreement (R2: 0.96 to 0.99) between observed and predicted bromide breakthrough curves could be achieved with the dual-porosity model using HYDRUS 1D. The bromide and P leaching trends indicated the existence of preferential flow. For the HYDRUS modeling component, the input soil hydraulic parameters (saturated hydraulic conductivity and porosity) were measured in the lab. The dual porosity with a two-site sorption model was used to identify the DRP transport and reaction parameters through calibration from the DRP breakthrough curves (BTCs) in a two-step process. In the first step, the solute transport parameters were estimated using the mobile-immobile physical nonequilibrium model to fit the bromide BTC in the inverse mode. Two parameters, dispersivity, and immobile water content were predicted simultaneously using the BTCs of bromide by inverse solution in HYDRUS. Further, the estimated parameters were used as input to run the DRP simulations in the inverse mode. Some of the reaction parameters required by the HYDRUS-1D model for DRP simulations were derived in the laboratory experiments, such as the Freundlich adsorption coefficients and bulk density, and four parameters (Frac, Frac_M, Omega, and Alpha) were optimized. A significant amount of immobile water content was present in all columns, indicating the existence of macropore flow. The model simulated the DRP concentrations adequately. The results showed that the average dispersivity was higher in the treatment columns as compared to the control columns, suggesting that the manure application altered the soil's physical properties so that the solute dispersion increased. The DRP BTCs were asymmetrical and exhibited tailing, indicating non-equilibrium sorption. The overall application of HYDRUS-1D in simulating preferential transport of DRP in undisturbed soil columns was effectively described by the implemented non-equilibrium solute transport model (dual porosity model with two-site sorption in the mobile zone). Overall results provide clear evidence of a greater risk of P leaching from columns with macropore networks. Therefore, the characterization of different P forms (dissolved, colloidal, and total P) is required to develop management practices to minimize P loss.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Malhotra, K., J. Lamba, T.R. Way, S. Budhathoki, and P. Srivastava. Impact of land use and tillage practice on preferential
transport of phosphorus. American Society of Agricultural and Biological Engineers Annual International Meeting, Houston,
Texas, July 17-20, 2022.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Malhotra, K., J. Lamba, T.R. Way, S. Budhathoki, and P. Srivastava. Subsurface transport of phosphorus in pasture soils:
Influence of preferential flow paths. American Society of Agricultural and Biological Engineers Annual International
Meeting, Houston, Texas, July 17-20, 2022.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Preetika, K., S. Budhathoki, K.Malhotra*, J.Lamba, and T.Way. 2022. Biopore Quantification based on macropores shape in pastures. [Poster]. Auburn Research Student Symposium, Auburn University, Alabama.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Preetika, K., J. Lamba, V. Sandhu*, T. R. Way, and Kip Balkcom. 2022. Effect of Cover Crop and Tillage Practice on Pore
Properties. 2022 ASA-CSSA-SSSA International Annual Meeting, November 6-9, Baltimore, MD.
|
Progress 05/01/21 to 04/30/22
Outputs
Target Audience:Environmental research community (both academic and non-academic; governmental and non-governmental). Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One Ph.D. and three M.S. level students contributed to this project. Students were trained to conduct laboratory experiments, perform hydrological modeling, and quantify various macropore characteristics in soil cores. Research results were presented at various conferences, and peer-reviewed publications were published in journals with a graduate student as the lead author of the articles. One MS student (Suman Budhathoki) who worked on this project graduated from Auburn University and is currently pursuing a Ph.D. at Virginia Tech University. How have the results been disseminated to communities of interest?The research results were presented at various conferences (e.g., American Society of Agricultural and Biological Engineers International Meeting, Alabama Water Resources Conference). Additionally, peer-reviewed articles were published in the journals to share research results with a broader audience. What do you plan to do during the next reporting period to accomplish the goals?We will finish the HYDRUS modeling and lab experiments, present research results, and publish peer-reviewed research articles.
Impacts
What was accomplished under these goals?
The results of X-ray CT scanning show that land use type and tillage practices can significantly affect the soil macropore characteristics, especially at the surface soil layer (0-100 mm). Fields under conventional tillage planted with corn had significantly higher surface area density, length density, interconnectivity, and network density than the soils under no-till corn fields. Conventional tillage caused disruption of the larger and continuous macropores. Soil cores sampled from no-till corn fields showed higher macropore diameter and macropore branch length compared to the conventional till field. The higher proportion of continuous and vertically oriented macropores in Alfalfa was closely associated with their deep penetrating root system. Soil cores collected from a pasture field in Alabama showed that the macropore characteristics can vary significantly between different topographical positions and sampling seasons, especially at the surface layer (0-100 mm) depth. The soil macropores at the downslope position were sparsely distributed in the surface soil layer. This was attributed to a relatively higher degree of grazing-induced compaction due to higher soil moisture as compared to the upslope and midslope locations. In contrast, dense macropore networks were observed at the downslope positions for depths greater than 250 mm. Rainfall simulations were conducted to quantify phosphorus loss in leachate at Auburn University and the University of Wisconsin-Madison. The shape of bromide breakthrough curves in columns collected from Alabama suggested the occurrence of preferential flow through macropores in the undisturbed soil columns at three different topographical locations (upslope, midslope, and downslope). This was supported by the X-Ray CT results that indicated the presence of macropore pathways at all topographical locations in the study area. The phosphorus loss from the columns fertilized with poultry litter was greater in columns collected from upslope positions relative to midslope and downslope positions. There could be two possible explanations for the higher P loss from columns collected from upslope compared to the downslope. Firstly, the interconnectivity, macroporosity, and the macropore number of the surface soil (0-25 cm) at the downslope location were significantly less as compared to the upslope location. Secondly, the soils at the upslope location had a significantly higher degree of P saturation than those at the downslope location. We also used HYDRUS model to simulate phosphorus loss in leachate. The non-equilibrium models fitted well with the observed data, indicating the presence of preferential flow in the soil columns. The cores collected from Wisconsin were used for rainfall simulation experiments at the UW-Madison, and similar trends were observed.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Budhathoki, S., J. Lamba, P. Srivastava, C. Williams, F. Arriaga and K.G. Karthikeyan. 2022. Impact of land use and tillage practice on soil macropore characteristics inferred from X-ray computed tomography. CATENA 210: 105886. doi:https://doi.org/10.1016/j.catena.2021.105886.
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Budhathoki., S., J. Lamba, P. Srivastava, K. Malhotra, T.R. Way, and S. Katuwal. 2022. Temporal and Spatial Variability in 3D Soil Macropore Characterstics Determined Using X-ray Computed Tomography. Journal of Soils and Sediments. https://doi.org/10.1007/s11368-022-03150-x
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Malhotra, K., J. Lamba, T. Way, S. Budhathoki, and P. Srivastava. Influence of manure application and soil physicochemical properties on phosphorus leaching in pastures. Alabama Water Resources Conference and Symposium, Orange Beach, Alabama, September 8-10, 2021.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Malhotra, K., J. Lamba, T. Way, J. Simunek, P. Srivastava and S. Budhathoki. Influence of Macropores on Phosphorus Leaching in Pastures: An Experimental and Modeling Study. American Society of Agricultural and Biological Engineers Annual International Meeting (Virtual), July 12-16, 2021.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Budhathoki, S., Lamba, J., Srivastava, P., Williams, C., Arriaga, F. and Karthikeyan, K. Quantification of 3-D soil macropore characteristics in different land uses using X-ray computed tomography. Alabama Water Resources Conference, Orange Beach, Alabama, September 8-10, 2021.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Budhathoki, S., Lamba, J., Srivastava, P., Williams, C., Arriaga, F. and Karthikeyan, K. Quantifying soil macropore characteristics under different land uses using Computed Tomography. ASABE A Virtual Meeting, July 12-16, 2021.
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Budhathoki., S., J. Lamba, P. Srivastava, K. Malhotra, S. Katuwal, and T. R. Way. 2022. Using X-ray Computed Tomography to Quantify Variability in Soil Macropore Characteristics in Pastures. Soil and Tillage Research. 215: 105194. doi:https://doi.org/10.1016/j.still.2021.105194.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Budhathoki, S., Lamba, J., Srivastava, P., Malhotra, K., Way, T. and Katuwal, S. Quantification of soil macropores in hillslope pastures using X-ray computed tomography. Alabama Water Resources Conference, Orange Beach, Alabama, September 8-10, 2021.
|
Progress 05/01/20 to 04/30/21
Outputs
Target Audience:Environmental research community (both academic and non-academic; governmental and non-governmental). Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Three graduate students (2 M.S. and 1 PhD)at UW-Madison and Auburn University were trained as a part of this project. Students were trained to interpret soil pore data fromImageJ version 1.52t software. They also received training to conduct column based rainfall simulation experiments. Research results were presented by students at various conferences. How have the results been disseminated to communities of interest?The research results were presented at various conferences (e.g.,American Society of Agricultural and Biological Engineers International Meeting,ASA, CSSA, SSSA International Annual Meeting). What do you plan to do during the next reporting period to accomplish the goals?Three dimesional macropore characerstics will be quanitied in soil cores. The rainfall simulation experiments and soil, water, and manure samples analysiswill be completed. Rainfall simulation experiments will be followed by HYDRUS modeling.
Impacts
What was accomplished under these goals?
Using X-ray Computed Tomography (X-ray CT) variation in 2 D soil macropore characteristics at different depths at upslope, midslope, and downslope locations within a pasture field was quantified. The results of this analysis show a clear and consistent evidence that macropore characteristic variation within the field was not random but indeed linked to the topographical position in the field. However, evidence of differences was observed only in the surface layer (0-100 mm). Similarly, topographical position influenced macropores of different sizes. For pores <1 mm diameter, both mean macropore number and macroporosity were significantly lower at the downslope location, at the surface layer (0-100 mm), compared to the soils at the upslope and midslope locations at the same depth. However, no significant differences were seen between the three topographical positions for pores >1 mm at any depths. Lower surface interconnectivity and limiting macroporosity values were observed at downslope positions as compared to the other slope positions. This likely resulted from higher degree of compaction due to trampling at the downslope location, which is expected to have a high soil moisture content compared to upslope and midslope locations. In addition, architecture of the plant roots appears to have played an important role in variation of macropore characteristics. In comparing the variability associated with using different diameters soil cores for characterizing macroporosity, we found that macroporosity and ECD measurements could be largely biased because of higher values of CV for a smaller diameter sub-volume cores compared to the larger diameter cores. This result gives confidence in using cores with larger diameters (≥150 mm) to better estimate parameters such as ECD and macroporosity. Leaching experiments have been completed for three soil cores: two from corn plots (no manure) and one alfalfa plot (with and without manure). The leachate samples have been analyzed for Br- (tracer), pH, and dissolved reactive phosphorus. Dairy manure samples used in the leachate experiments are being analyzed for total phosphorus, water-extractable phosphorus, total N, minerals and solids content (at the UW Soil and Forage Laboratory, Marshfield WI). Application of manure has been adjusted to avoid core clogging and separation of dissolved vs colloidal content of leachate: most notably, removal of fiber material and adjustments of application rate. Data from tensiometers and CS655 sensors have been collected, including matric potential, volumetric water content, and EC inside of cores. Ultracentrifugation procedure has been developed. Samples processed for colloidal nutrient and mineral content are centrifuged at 300,000g for 30 min. During this process, it was estimated that particles of approximately 80-100 Svedberg units and larger are separated.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Budhathoki., S., J. Lamba, P. Srivastava, K. Malhotra, S. Katuwal, and T. R. Way. 2020. Assessment of Temporal Variation in Soil Macropore Characteristics in a Pasture Field. ASABE 2020 AIM - A Virtual Meeting.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Budhathoki., S., J. Lamba, P. Srivastava, K. Malhotra, S. Katuwal, and T. R. Way. 2020. Using X-ray Computed Tomography to Quantify Soil Macropore Characteristics. ASABE 2020 AIM - A Virtual Meeting.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Budhathoki., S., J. Lamba, P. Srivastava, K. Malhotra, S. Katuwal, and T. R. Way. 2020. Characterizing soil macropore structure at different slope positions in a hillslope pasture using X-ray Computed tomography. ASA, CSSA and SSSA International Annual Meetings (2020)| VIRTUAL
- Type:
Conference Papers and Presentations
Status:
Submitted
Year Published:
2020
Citation:
Malhotra., K., J. Lamba, T. R. Way, S. Budhathoki, and R. Prasad. 2020. Phosphorus Leaching through Undisturbed Soil Cores: Influence of Preferential Flow Paths. ASA, CSSA and SSSA International Annual Meetings (2020)| VIRTUAL
- Type:
Journal Articles
Status:
Submitted
Year Published:
2021
Citation:
Budhathoki., S., J. Lamba, P. Srivastava, K. Malhotra, S. Katuwal, and T. R. Way. 2021. Using X-ray Computed Tomography to Quantify Variability in Soil Macropore Characteristics in Pastures. Soil and Tillage Research.
- Type:
Journal Articles
Status:
Submitted
Year Published:
2021
Citation:
Malhotra., K., J. Lamba, S. Oladipupo, A. Wilson, and T.R. Way. 2021. A Meta-Analysis of Phosphorus Loss in Soil Leachate: Implications for Water Quality. Water, Air, & Soil Pollution.
|
Progress 05/01/19 to 04/30/20
Outputs
Target Audience:Environmental research community (both academic and non-academic; governmental and non-governmental). Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The graduate students(MS student, Colleen Williams in Civil & Environmental Engineering at UW-Madison and Kritika Malhotra, Ph.D. student in Biosystems Engineering at Auburn University) have been trained on soil sampling and testing, column study setup, use of sensors and logging data,and instrument training (for AQ2 discrete analyzer). Additionally, a graduate student (MS student, Suman Budhathoki in Biosystems Engineering at Auburn University) received training in soil sample collection and analysis and use of ImageJ version 1.52t software to determine the 2D and 3D macropore characteristics in soil cores. How have the results been disseminated to communities of interest?The research results on characterization of soil macropore characteristics in soil cores were presented at Auburn Research: Virtual Student Symposium, Auburn University, Auburn, AL. What do you plan to do during the next reporting period to accomplish the goals?The following analyses will be completed on manure and soil samples: pH, electrical conductivity, water-dispersible colloids, organic matter, soil texture, total phosphorus, dissolved reactive phosphorus, ammonium, nitrate. Additional soil macropore characteristics will be computed using X-ray Computed Tomography data. Rainfall simulation experiments will be conducted and HYDRUS modeling will be performed. Additional soil cores will be collected in fall 2020. Research results will be presented at national/international conferences.
Impacts
What was accomplished under these goals?
During this project period, 18 undisturbed soil cores were collected from the Arlington Agricultural Research Station in Wisconsin during two different times (spring and fall 2019). The fields covered several land use/land cover combinations: No-till and conventional till corn, alfalfa, and native grass vegetation. A total of 36 intact, undisturbed soil cores were collected at three different topographical positions (upslope, midslope and downslope) for 2 seasons (May and September 2019) from a pasture field located at the Sand Mountain Research and Extension Center, Crossville, AL. For the collection of these undisturbed soil cores, we fabricated long PVC cylinders, machined the edges and drilled holes for the purpose of inserting the tensiometers and water content reflectometers in the cores. The soil cores collected from AL were scanned using a medical GE LightSpeed VCT 64 Slice CT scanner installed in the Bailey Small Animal Teaching Hospital at the Auburn University College of Veterinary Medicine. Similarly the cores collected in Wisconsin were scanned at UW-Madison. After scanning, all the images were analyzed using a software ImageJ version 1.52t to determine the 2D and 3D macropore characteristics. In the 2D analysis, macroporosity, macropore number and diameter were quantified as a function of depth and slope position. On the other hand, macroporosity, connectivity, length density, surface area density, network density, tortuosity and mean diameter (thickness) were quantified in 3D. The rainfall simulation protocols are being finalized for simulation experiments. The Soil Measurement Systems tensiometers which will be used during the rainfall simulation experiment were calibrated. These sensors were calibrated using an electronic barometer and by plotting bars or pressure measured (negative in this case) versus (mV response)/(V input). The Campbell Scientific frequency domain reflectometers were calibrated before shipment and conditions they will be used in (soil and temperature) are within the range of effective use without additional calibration. Additional loose soil samples were collected as a function of depth at the study site located in AL. These samples were collected adjacent to the undisturbed soil cores. The depth intervals considered were 0-5, 5-10, 10-15, 15-20, 20-30, 30-40, and 40-50 cm. The loose soil samples are currently being analyzed for various nutrients. Additionally, soil samples were analyzed for texture, organic matter, and moisture content.
Publications
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2020
Citation:
Budhathoki, S., J. Lamba, P. Srivastava, K. Malhotra, T.R. Way, and S. Katuwal. 2020. Quantifying variability in soil macropore characteristics in a pasture field. Auburn Research:Virtual Student Symposium, Auburn University, Auburn, AL.
|
Progress 05/01/18 to 04/30/19
Outputs
Target Audience:Environmental research community (both academic and non-academic; governmental and non-governmental). Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The students working on this project learned to collect intact undisturbed soil cores and developed protocols for scanning soil cores using X-ray Computed Tomography. Additionally, project PI (Jasmeet Lamba) and PhD level student working on this project attended a 3-day HYDRUS model short-course workshop organized by the project Co-PI Jirka Simunek at the Colorado School of Mines, Golden, CO. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?Activities to be performed this year include rainfall simulation experiments on large intact soil columns, determination of essential soil physicochemical properties using small soil cores (7.5 cm * 7.5 cm), scanning soil cores using X-ray Computed Tomography and modeling nutrient losses using HYDRUS model.
Impacts
What was accomplished under these goals?
We are in Year 1 of the project, so activities conducted to-date include identifying/recruiting/hiring appropriate project personnel (specifically, graduate students, undergraduate researcher, and academic staff for technical help). In Alabama, we collected 18 intact undisturbed soil cores (15 cm diameter and 50 cm deep) from a pasture field at the Sand Mountain Research and Experimentation Center, Crossville, AL. The soil cores were collected from three different topographic locations (upslope, midslope, and downslope). In addition to intact undisturbed soil cores, soil cores were collected at different depth increments to determine soil physical and chemical characteristics. Soil macropore characteristics are expected to vary as a function of topographic location within a field. We are in the process of scanning the soil cores using X-ray Computed Tomography (CT) in an effort to quantify soil macropore characteristics. The graduate students working on this project finalized the protocols for CT scanning. After performing CT scanning, rainfall simulation experiments will be conducted on these cores. In Wisconsin (at the 2nd project site), three fields with contrasting management practices (row-crop (tilled), alfalfa, grass) expected to yield diverse macropore characteristics have been selected at the Arlington Agricultural Research Station. Notably, these fields have been under these specific management practices for the past few years. In addition, we have tested our equipment to collect large intact soil columns (15 cm diameter * 50 cm deep) and have obtained multiple soil columns for each field treatment. The columns are currently being prepared for rainfall simulation experiments.
Publications
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