Submitted to: Geoderma
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/2/2000
Publication Date: 1/1/2001
Citation: SHAW, J.N., BOSCH, D.D., WEST, L.T., TRUMAN, C.C., RADCLIFFE, D.E. EVIDENCE OF LATERAL FLOW IN SE (USA) UPPER COASTAL PLAIN KANDIUDULTS WITH LOAMY TO SANDY ARGILLIC HORIZONS. GEODERMA. 99:1-25. 2001. Interpretive Summary: As our need for fresh water sources increases, the concern over possible sources of water contamination also increases. Discovery of water contamination due to agricultural chemicals has led to the acknowledgment of a need for better agricultural management and for a better understanding of how the chemicals move through the soil. Changes in the soil both on and below the land surface dramatically influence how water and chemicals move through the environment. Often, layering within the soil causes water and chemicals to flow laterally through the soil rather than vertically. A field research study was conducted to quantify the effects of soil layers on water flow and chemical transport. The study indicated the layering within the sandy soils studied caused lateral movement within the area of the soil containing plant roots. However, the overall effect was not as large as was expected. This was attributed to the fact that the overall variability within the soils studied was small in comparison to that found within many other soils throughout the world. These results help scientists to better understand how chemicals move through the soil. This study will assist land managers in developing better management methods for preventing environmental problems due to agricultural practices.
Technical Abstract: Interest in site-specific agronomic management in intensively cropped areas requires characterization of subsurface water movement for efficient water management and control of off-site agrichemical movement. Soils formed in fluvial sediments in parts of the Upper Coastal Plain of GA are extensively used for peanut, cotton and corn production. Certain proximate soils in the region possess contrasting subsoil properties and it was hypothesized that these differences would have major effects on water redistribution across the landscape. This could be important in irrigation management where soils having increased impedance to vertical flow could require decreased irrigation as opposed to soils without vertical flow restrictions. At a site near Plains, GA hydraulic properties of soils with differences in overlying sand thickness and contrasting argillic horizon textures were evaluated. Soils were mostly in loamy and sandy families of Typic, Arenic and Grossarenic Kandiudults. Laboratory measurements, field monitoring of matric potentials under simulated and natural rainfall and modeling were used to evaluate soil hydraulic properties. Reduction in vertical Ks occurred in horizons having higher clay. Changes in tension and buildups in hydraulic gradients associated with infiltration and redistribution events were most pronounced over horizons with low Ks. Evidence suggested there was less groundwater recharge occurring in loamy than in sandy pedons, suggesting more pronounced lateral flow occurred in loamier soils. Evidence suggested both loamy and sandy argillic horizons slightly, but not overwhelmingly, induced lateral flow on these landscapes.