Progress 09/01/99 to 08/31/04
Outputs
We investigatied the distributions of water and chemical flow paths along with distributions of rooting densities in a highly structured vertic clay soil under conventional tillage with a row crop and under continuous pasture. Experiments were duplicated. Plots 6 m by 6 m were established on Ships Clay. Irrigation water containing erioglaucine (Brilliant Blue FCF) was applied to the 3 m by 3 m plot center in continuous pasture. After irrigation with the staining solution, incremental horizontal planes were exposed by excavation with hand tools. Dye stained flow paths were mapped by digital photography. Root distributions were mapped by tracing root intersections on clear plastic sheets. Root location data were digitized. Dye-stain and root location data were analyzed with spatial statistical program. In addition, a program was developed in Visual Basic to analyze the combined flow path and root density data for spatial association. Statistical analysis showed that the
roots exposed on the horizontal slice were clustered. As analyzed by the Visual Basic program, root densities of the largest roots were greater in the stained flow paths than outside the flow paths. Root densities of small roots were randomly distributed relative to the dye-stained water and chemical flow paths.
Impacts
The information gained from this project has improved our ability to predict the fate of water, nutrients, and contaminants in soil. It has provided understanding of how plants influence the water cycle and water quality. The research determined the spatial associations between plant roots and water and chemicals flow paths, and allowed the determination of the significance of the associations to water management.
Publications
- Nobles, M. M., L. P. Wilding and K. J. McInnes. 2004. Submicroscopic measurements of tracer distribution related to surface features of soil aggregates. Geoderma (in press).
- Nobles, M. M., L. P. Wilding and K. J. McInnes. 2004. Pathways of dye tracer movement through structured soils on macroscopic scale. Soil Science 169:229-242.
- Nobles, M. M., L. P. Wilding, and K. J. McInnes. 2003. Soil structural interfaces in some Texas Vertisols and their impact on solute transport. Catena 54:477-493.
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Progress 01/01/03 to 12/31/03
Outputs
We are investigating the distributions of flow paths and rooting densities in a highly structured vertic soil under conventional tillage with a row crop and under continuous pasture. Experiments were duplicated. Plots 6 m by 6 m were established on Ships Clay. Irrigation water containing erioglaucine (Brilliant Blue FCF) was applied to the 3 m by 3 m plot center in continuous pasture. After irrigation with the staining solution, incremental horizontal planes were exposed by excavation with hand tools. Dye stained flow paths were mapped by digital photography. Root distributions were mapped by tracing root intersections on clear plastic sheets. Soil samples were collected from stained and unstained areas and roots were extracted from the soil and measured for mass and total length. Data were digitized. Data were analyzed with S-Plus statistical program. In addition, a program was developed in Visual Basic to analyze the combined flow path and root density data for
spatial association. S-Plus statistical analysis showed that the roots exposed on the horizontal slice were clustered. As analyzed by the Visual Basic program, root densities of the largest roots were greater in the stained flow paths than outside the flow paths. Root densities of small roots were randomly distributed. We are presently developing a model that simulates the growth of roots as controlled by soil physical conditions, while at the same time influencing these same physical conditions.
Impacts
The information gained from this project will improve our ability to predict the fate of water, nutrients, and contaminants in soil. It will provide for a major conceptual breakthrough on the understanding of how plants influence the water cycle and water quality. The objectives of the research are to determine the spatial associations between plant roots and water and chemicals flow paths, and then to determine the significance of the associations to water management.
Publications
- Nobles, M. M., L. P. Wilding, and K. J. McInnes. 2003. Soil structural interfaces in some Texas Vertisols and their impact on solute transport. Catena (in press).
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Progress 01/01/02 to 12/31/02
Outputs
We are investigating the distributions of flow paths and rooting densities in a highly structured vertic soil under conventional tillage with a row crop and under continuous pasture. Experiments are being duplicated. Plots 6 m by 6 m were established on Ships Clay. Irrigation water containing a combination of erioglaucine (Brilliant Blue FCF) and potassium iodide was applied to the 3 m by 3 m plot center in continuous pasture. After irrigation with the staining solution, incremental horizontal planes were exposed by excavation with hand tools. Dye stained flow paths were mapped by digital photography. Root distributions were mapped by tracing root intersections on clear plastic sheets. Soil samples were collected from stained and unstained areas and roots were extracted from the soil and measured for mass and total length. Data were digitized. Data were analyzed with S-Plus statistical program. In addition, a program was developed in Visual Basic to analyze the
combined flow path and root density data for spatial association. S-Plus statistical analysis showed that the roots exposed on the horizontal slice were clustered. As analyzed by the Visual Basic program, root densities were greater in the stained flow paths than outside the flow paths. We are presently developing a model that simulates the growth of roots as controlled by soil physical conditions, while at the same time influencing these same physical conditions.
Impacts
Major land resources in the US include areas with a high percentage of clayey surface soils or subsoils. Many of soils in these areas are highly structured. Clayey soils are abundant in the central, southern and eastern parts of Texas. This research benefits water conservation and the availability of high quality water resources within these regions: two crucial issues for sustainable and enhanced agriculture and urban developments.
Publications
- Nobles, M. M., L. P. Wilding, and K. J. McInnes. 2002. Soil structural interfaces in some Texas Vertisols and their impact on solute transport. Catena (in press).
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Progress 01/01/01 to 12/31/01
Outputs
We are investigating the distributions of flow paths and rooting densities in a highly structured vertic soil under conventional tillage with a row crop and under continuous pasture. Experiments are being duplicated. Plots 6 m by 6 m were established on Ships Clay. Irrigation water containing a combination of erioglaucine (Brilliant Blue FCF) and potassium iodide was applied to the 3 m by 3 m plot center in continuous pasture. After irrigation with the staining solution, incremental horizontal planes were exposed by excavation with hand tools. Dye stained flow paths were mapped by digital photography. Root distributions were mapped by tracing root intersections on clear plastic sheets. Soil samples were collected from stained and unstained areas and roots were extracted from the soil and measured for mass and total length. Data were digitized. Data were analyzed with S-Plus statistical program. In addition, a program was developed in Visual Basic to analyze the
combined flow path and root density data for spatial association. S-Plus statistical analysis showed that the roots exposed on the horizontal slice were clustered. As analyzed by the Visual Basic program, root densities were greater in the stained flow paths than outside the flow paths. We are presently developing a model that simulates the growth of roots as controlled by soil physical conditions, while at the same time influencing these same physical conditions.
Impacts
Major land resources in the US include areas with a high percentage of clayey surface soils or subsoils. Many of soils in these areas are highly structured. Clayey soils are abundant in the central, southern and eastern parts of Texas. This research benefits water conservation and the availability of high quality water resources within these regions: two crucial issues for sustainable and enhanced agriculture and urban developments.
Publications
- Schwartz, R. C., A. S. R. Juo, and K. J. McInnes. 2000. Estimating parameters for a dual-porosity model to describe non-equilibrium, reactive transport in a fine-textured soil. J. Hydrol. 229: 149-167.
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Progress 01/01/00 to 12/31/00
Outputs
We are investigating the distributions of flow paths and rooting densities in a highly structured vertic soil under conventional tillage with a row crop and under continuous pasture. Experiments are being duplicated. Plots 6 m by 6 m have been established. Irrigation water containing a combination of erioglaucine (Brilliant Blue FCF) and potassium iodide is being applied to the 3 m by 3 m plot center. After irrigation with the staining solution, incremental horizontal planes are being exposed by excavation with hand tools. Erioglaucine marked flow paths are being mapped by digital photography. Iodide marked flow paths are being exposed by spraying the horizontal surface with starch and bleaching solution (NaOCl). The exposed iodide flow paths are being photographically mapped on the same grid as those for the erioglaucine flow paths. Root distributions are being mapped by tracing root intersections on clear plastic sheets. Soil samples are being collected from stained
and unstained areas and roots are being extracted from the soil and measured for mass and total length. Samples are being taken on a rectangular grid with the fineness of mesh allowed to vary based on areal root densities and dye stain pattern. Data are being digitized then we are determining if there are statistically different root densities in dyed and undyed areas. Later, we will then investigate the relationships between the root density, flow path, and crack pattern variables. After the spatial associations are found, we will evaluate our understanding of the system with a model that simulates the growth of roots as controlled by soil physical conditions, while at the same time influencing these conditions.
Impacts
Major land resources in the US include areas with a high percentage of clayey surface soils or subsoils. Many of soils in these areas are highly structured. Clayey soils are abundant in the central, southern and eastern parts of Texas. This research benefits water conservation and the availability of high quality water resources within these regions: two crucial issues for sustainable and enhanced agriculture and urban developments.
Publications
- No publications reported this period
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Progress 09/01/99 to 12/31/99
Outputs
This project began September 1, 1999. Equipment has been purchased to conduct the proposed experiments beginning in the spring of 2000. A rainfall simulator is being constructed to supply dye containing water to a 3 by 3 m soil surface. Experimental plots are being established.
Impacts
The information gained from this project will improve our ability to predict the fate of water, nutrients, and contaminants in soil. It will provide for a major conceptual breakthrough on the understanding of how plants influence the water cycle and water quality. The objectives of the research are to determine the spatial associations between plant roots and water and chemicals flow paths, and then to determine the significance of the associations to water management.
Publications
- No publications reported this period
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